View MAX6956_305190.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-2414; Rev 1; 2/03
3-16-03 F3 JF
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander
General Description
The MAX6956 compact, serial-interfaced LED display driver/I/O expander provide microprocessors with up to 28 ports. Each port is individually user configurable to either a logic input, logic output, or common-anode (CA) LED constant-current segment driver. Each port configured as an LED segment driver behaves as a digitally controlled constant-current sink, with 16 equal current steps from 1.5mA to 24mA. The LED drivers are suitable for both discrete LEDs and CA numeric and alphanumeric LED digits. Each port configured as a general-purpose I/O (GPIO) can be either a push-pull logic output capable of sinking 10mA and sourcing 4.5mA, or a Schmitt logic input with optional internal pullup. Seven ports feature configurable transition detection logic, which generates an interrupt upon change of port logic level. The MAX6956 is controlled through an I2CTM-compatible 2-wire serial interface, and uses four-level logic to allow 16 I 2C addresses from only 2 select pins. The MAX6956AAX and MAX6956ATL have 28 ports and are available in 36-pin SSOP and 40-pin thin QFN packages, respectively. The MAX6956AAI and MAX6956ANI have 20 ports and are available in 28-pin SSOP and 28-pin DIP packages, respectively.
2
Features
o 400kbps I C-Compatible Serial Interface o 2.5V to 5.5V Operation o -40C to +125C Temperature Range o 20 or 28 I/O Ports, Each Configurable as Constant-Current LED Driver Push-Pull Logic Output Schmitt Logic Input Schmitt Logic Input with Internal Pullup o 11A (max) Shutdown Current o 16-Step Individually Programmable Current Control for Each LED o Logic Transition Detection for Seven I/O Ports
MAX6956
Ordering Information
PART MAX6956ANI MAX6956AAI MAX6956AAX MAX6956ATL TEMP RANGE -40C to +125C -40C to +125C -40C to +125C -40C to +125C PIN-PACKAGE 28 DIP 28 SSOP 36 SSOP 40 Thin QFN
Applications
Set-Top Boxes Panel Meters White Goods Automotive Bar Graph Displays Industrial Controllers System Monitoring
TOP VIEW
ISET 1 GND 2 GND 3 AD0 4 P12 5 P13 6 P14 7
Pin Configurations
28 V+ 27 AD1 26 SCL 25 SDA 24 P31
MAX6956
23 P30 22 P29 21 P28 20 P27 19 P26 18 P25 17 P24 16 P23 15 P22
Typical Operating Circuit appears at end of data sheet.
P15 8 P16 9 P17 10 P18 11 P19 12 P20 13
I 2C is a trademark of Philips Corp.
P21 14
SSOP/DIP
Pin Configurations are continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
ABSOLUTE MAXIMUM RATINGS
Voltage (with Respect to GND) V+ .............................................................................-0.3V to +6V SCL, SDA, AD0, AD1................................................-0.3V to +6V All Other Pins................................................-0.3V to (V+ + 0.3V) P4-P31 Current ................................................................30mA GND Current .....................................................................800mA Continuous Power Dissipation 28-Pin PDIP (derate 20.8mW/C above TA = +70C)1667mW 28-Pin SSOP (derate 9.5mW/C above TA = +70C) ..762mW 36-Pin SSOP (derate 11.8mW/C above TA = +70C) ..941mW 40-Pin QFN (derate 26.3mW/C above TA = +70C) ..2105mW Operating Temperature Range (TMIN to TMAX) ..............................................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(Typical Operating Circuit, V+ = 2.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER Operating Supply Voltage Shutdown Supply Current SYMBOL V+ ISHDN CONDITIONS TA = +25C TA = -40C to +85C TA = TMIN to TMAX All ports programmed as outputs high, no load, all other inputs at V+ or GND All ports programmed as outputs low, no load, all other inputs at V+ or GND TA = +25C TA = -40C to +85C TA = TMIN to TMAX TA = +25C TA = -40C to +85C TA = TMIN to TMAX 110 170 180 MIN 2.5 TYP 5.5 MAX 5.5 8 10 11 230 250 270 210 230 240 135 140 145 0.7 V+ 0.3 V+ GPIO inputs without pullup, VPORT = V+ to GND V+ = 2.5V V+ = 5.5V GPIO outputs, ISOURCE = 2mA, TA = -40C to +85C GPIO outputs, ISOURCE = 1mA, TA = TMIN to TMAX (Note 2) VPORT = 0.6V Port configured output low, shorted to V+ -100 12 80 V+ 0.7 V+ 0.7 2 2.75 10 11 18 20 1 19 120 0.3 +100 30 180 A A A A UNITS V
All digital inputs at V+ or GND
Operating Supply Current
IGPOH
Operating Supply Current
IGPOL
Operating Supply Current
ILED
All ports programmed TA = +25C as LED outputs, all LEDs TA = -40C to +85C off, no load, all other inputs at V+ or GND TA = TMIN to TMAX
INPUTS AND OUTPUTS Logic-High Input Voltage Port Inputs Logic-Low Input Voltage Port Inputs Input Leakage Current GPIO Input Internal Pullup to V+ Hysteresis Voltage GPIO Inputs VIH VIL IIH, IIL IPU VI V V nA A V
Output High Voltage
VOH
V
Port Sink Current Output Short-Circuit Current
IOL IOLSC
mA mA
2
_______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander
ELECTRICAL CHARACTERISTICS (continued)
(Typical Operating Circuit, V+ = 2.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS V+ = 2.5V, VLED = 2.3V at maximum LED current V+ = 3.3V, VLED = 2.4V at maximum LED IDIGIT current (Note 2) V+ = 5.5V, VLED = 2.4V at maximum LED current V+ = 2.5V, VOUT = 0.6V at maximum sink current IDIGIT_SC V+ = 5.5V, VOUT = 0.6V at maximum sink current VIH VIL IIH, IIL VOL (Note 2) ISINK = 6mA -50 MIN 9.5 18.5 19 18.5 19 0.7 V+ 0.3 V+ 50 10 0.4 TYP 13.5 24 25 23 24 MAX 18 27.5 30 28 mA 28 V V nA pF V mA UNITS
MAX6956
Port Drive LED Sink Current, Port Configured as LED Driver
Port Drive Logic Sink Current, Port Configured as LED Driver Input High-Voltage SDA, SCL, AD0, AD1 Input Low-Voltage SDA, SCL, AD0, AD1 Input Leakage Current SDA, SCL Input Capacitance Output Low-Voltage SDA
TIMING CHARACTERISTICS (Figure 2)
(V+ = 2.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER Serial Clock Frequency Bus Free Time Between a STOP and a START Condition Hold Time (Repeated) START Condition Repeated START Condition Setup Time STOP Condition Setup Time Data Hold Time Data Setup Time SCL Clock Low Period SCL Clock High Period Rise Time of Both SDA and SCL Signals, Receiving Fall Time of Both SDA and SCL Signals, Receiving Fall Time of SDA Transmitting SYMBOL fSCL tBUF tHD, STA tSU, STA tSU, STO tHD, DAT tSU, DAT tLOW tHIGH tR tF tF,TX (Note 3) CONDITIONS MIN 1.3 0.6 0.6 0.6 15 100 1.3 0.7 20 + 0.1Cb 20 + 0.1Cb 20 + 0.1Cb 900 TYP MAX 400 UNITS kHz s s s s ns ns s s ns ns ns
(Notes 2, 4) (Notes 2, 4) (Notes 2, 5)
300 300 250
Pulse Width of Spike Suppressed tSP (Notes 2, 6) 0 50 ns Capacitive Load for Each Bus (Note 2) 400 pF Cb Line Note 1: All parameters tested at TA = +25C. Specifications over temperature are guaranteed by design. Note 2: Guaranteed by design. Note 3: A master device must provide a hold time of at least 300ns for the SDA signal (referred to VIL of the SCL signal) in order to bridge the undefined region of SCL's falling edge. Note 4: Cb = total capacitance of one bus line in pF. tR and tF measured between 0.3V+ and 0.7V+. Note 5: ISINK 6mA. Cb = total capacitance of one bus line in pF. tR and tF measured between 0.3V+ and 0.7V+. Note 6: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.
_______________________________________________________________________________________
3
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
__________________________________________Typical Operating Characteristics
(RISET = 39k, TA = +25C, unless otherwise noted.)
OPERATING SUPPLY CURRENT vs. TEMPERATURE
0.36 0.32 SUPPLY CURRENT (mA) 0.28 0.24 0.20 0.16 0.12 0.08 0.04 0 -40.0 -12.5 15.0 42.5 70.0 97.5 125.0 TEMPERATURE (C) ALL PORTS LED (OFF) 3 -40.0 ALL PORTS OUTPUT (1) ALL PORTS OUTPUT (0) V+ = 2.5V TO 5.5V NO LOAD
MAX6956 toc01
SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
MAX6956 toc02
OPERATING SUPPLY CURRENT vs. V+ (NO LOADS)
ALL PORTS LED (ON) SUPPLY CURRENT (mA) 10 ALL PORTS OUTPUT (1) 1 ALL PORTS OUTPUT (0)
MAX6956 toc03
0.40
8 V+ = 5.5V 7 SUPPLY CURRENT (A) V+ = 3.3V 6
100
5
V+ = 2.5V
0.1 4 ALL PORTS LED (OFF) 0.01 -12.5 15.0 42.5 70.0 97.5 125.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 TEMPERATURE (C) V+ (V)
LED DRIVER SINK CURRENT vs. V+
MAX6956 toc04
LED DRIVER SINK CURRENT vs. TEMPERATURE
MAX6956 toc05
GPO SINK CURRENT vs. TEMPERATURE (OUTPUT = 0)
V+ = 2.5V TO 5.5V, VPORT = 0.6V 16 PORT SINK CURRENT (mA) 14 12 10 8 6 4 2
MAX6956 toc06
26 24 PORT SINK CURRENT (mA) 22 20 18 16 14 12 10 8 6 2.0 2.5 3.0 3.5 4.0 4.5 5.0 LED DROP = 1.8V LED DROP = 2.4V
27 VLED = 2.4V 26 PORT SINK CURRENT (mA) 25 24 23 V+ = 3.3V 22 21 20 V+ = 5.5V
18
5.5
-40.0
-12.5
15.0
42.5
70.0
97.5
125.0
-40.0
-12.5
15.0
42.5
70.0
97.5
125.0
V+ (V)
TEMPERATURE (C)
TEMPERATURE (C)
GPO SOURCE CURRENT vs. TEMPERATURE (OUTPUT = 1)
MAX6956 toc07
GPI PULLUP CURRENT vs. TEMPERATURE
MAX6956 toc08
GPO SHORT-CIRCUIT CURRENT vs. TEMPERATURE
MAX6956 toc09
9 VPORT = 1.4V 8 PORT SOURCE CURRENT (mA) 7 6 5 4 3 2 -40.0 -12.5 15.0 42.5 70.0 97.5 V+ = 5.5V V+ = 3.3V V+ = 2.5V
1000
100
PULLUP CURRENT (A)
V+ = 5.5V
PORT CURRENT (mA)
GPO = 0, PORT SHORTED TO V+ 10
100 V+ = 3.3V
V+ = 2.5V 10 125.0 -40.0 -12.5 15.0 42.5 70.0 97.5 125.0 TEMPERATURE (C) TEMPERATURE (C) 1 -40.0
GPO = 1, PORT SHORTED TO GND -12.5 15.0 42.5 70.0 97.5 125.0
TEMPERATURE (C)
4
_______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander
Pin Description
PIN SSOP/DI 1 2, 3 4 SSOP 1 2, 3 4 THIN QFN 36 37, 38, 39 40 NAME ISET GND AD0 FUNCTION Segment Current Setting. Connect ISET to GND through a resistor (RISET) to set the maximum segment current. Ground Address Input 0. Sets device slave address. Connect to either GND, V+, SCL, SDA to give four logic combinations. See Table 3. LED Segment Drivers and GPIO. P12 to P31 can be configured as CA LED drivers, GPIO outputs, CMOS logic inputs, or CMOS logic inputs with weak pullup resistor. LED Segment Drivers and GPIO. P4 to P31 can be configured as CA LED drivers, GPIO outputs, CMOS logic inputs, or CMOS logic inputs with weak pullup resistor. No Connection I2C-Compatible Serial Data I/O I2C-Compatible Serial Clock Input Address Input 1. Sets device slave address. Connect to either GND, V+, SCL, SDA to give four logic combinations. See Table 3. Positive Supply Voltage. Bypass V+ to GND with minimum 0.047F capacitor.
MAX6956
5-24
--
--
P12-P31
-- -- 25 26 27 28
5-32 -- 33 34 35 36
1-10, 12-19, 21-30 11, 20, 31 32 33 34 35
P4-P31 N.C. SDA SCL AD1 V+
Detailed Description
The MAX6956 LED driver/GPIO peripheral provides up to 28 I/O ports, P4 to P31, controlled through an I2C-compatible serial interface. The ports can be configured to any combination of constant-current LED drivers, logic inputs and logic outputs, and default to logic inputs on power-up. When fully configured as an LED driver, the MAX6956 controls up to 28 LED segments with individual 16-step adjustment of the constant current through each LED segment. A single resistor sets the maximum segment current for all segments, with a maximum of 24mA per segment. The MAX6956 drives any combination of discrete LEDs and CA digits, including sevensegment and starburst alphanumeric types. Figure 1 is the MAX6956 functional diagram. Any I/O port can be configured as a push-pull output (sinking 10mA, sourcing 4.5mA), or a Schmitt-trigger logic input. Each input has an individually selectable internal pullup resistor. Additionally, transition detection allows seven ports (P24 through P30) to be monitored in any maskable combination for changes in their logic status. A detected transition is flagged through a status register bit, as well as an interrupt pin (port P31), if desired. The Typical Operating Circuit shows two MAX6956s working together controlling three monocolor 16-seg-
ment-plus-DP displays, with five ports left available for GPIO (P26-P31 of U2). The port configuration registers set the 28 ports, P4 to P31, individually as either LED drivers or GPIO. A pair of bits in registers 0x09 through 0x0F sets each port's configuration (Tables 1 and 2). The 36-pin MAX6956AAX has 28 ports, P4 to P31. The 28-pin MAX6956ANI and MAX6956AAI make only 20 ports available, P12 to P31. The eight unused ports should be configured as outputs on power-up by writing 0x55 to registers 0x09 and 0x0A. If this is not done, the eight unused ports remain as floating inputs and quiescent supply current rises, although there is no damage to the part.
Register Control of I/O Ports and LEDs Across Multiple Drivers
The MAX6956 offers 20 or 28 I/O ports, depending on package choice. These can be applied to a variety of combinations of different display types, for example: seven, 7-segment digits (Figure 7). This example requires two MAX6956s, with one digit being driven by both devices, half by one MAX6956, half by the other (digit 4 in this example). The two drivers are static, and therefore do not need to be synchronized. The MAX6956 sees CA digits as multiple discrete LEDs. To
5
_______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 1. Port Configuration Map
REGISTER Port Configuration for P7, P6, P5, P4 Port Configuration for P11, P10, P9, P8 Port Configuration for P15, P14, P13, P12 Port Configuration for P19, P18, P17, P16 Port Configuration for P23, P22, P21, P20 Port Configuration for P27, P26, P25, P24 Port Configuration for P31, P30, P29, P28 ADDRESS CODE (HEX) 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F REGISTER DATA D7 P7 P11 P15 P19 P23 P27 P31 D6 D5 P6 P10 P14 P18 P22 P26 P30 D4 D3 P5 P9 P13 P17 P21 P25 P29 D2 D1 P4 P8 P12 P16 P20 P24 P28 D0
Table 2. Port Configuration Matrix
MODE FUNCTION PORT REGISTER Written Low Output LED Segment Driver Written High PIN BEHAVIOR ADDRESS CODE (HEX) PORT CONFIGURATION BIT PAIR UPPER High impedance Open-drain current sink, with sink current (up to 24mA) determined by the appropriate current register Active-low logic output Active-high logic output Schmitt logic input Schmitt logic input with pullup 0x09 to 0x0F 0 0 LOWER
Output Input Input
GPIO Output GPIO Input Without Pullup GPIO Input with Pullup
Written Low Written High Reading Port Reading Port
0x09 to 0x0F 0x09 to 0x0F 0x09 to 0x0F
0 1 1
1 0 1
Note: The logic is inverted between the two output modes; a high makes the output go low in LED segment driver mode (0x00) to turn that segment on; in GPIO output mode (0x01), a high makes the output go high.
simplify access to displays that overlap two MAX6956s, the MAX6956 provides four virtual ports, P0 through P3. To update an overlapping digit, send the same code twice as an eight-port write, once to P28 through P35 of the first driver, and again to P0 through P7 of the second driver. The first driver ignores the last 4 bits and the second driver ignores the first 4 bits. Two addressing methods are available. Any single port (bit) can be written (set/cleared) at once; or, any sequence of eight ports can be written (set/cleared) in any combination at once. There are no boundaries; it is equally acceptable to write P0 through P7, P1 through P8, or P31 through P38 (P32 through P38 are nonexistent, so the instructions to these bits are ignored). Using 8-bit control, a seven-segment digit with a decimal point can be updated in a single byte-write, a 14segment digit with DP can be updated in two
6
byte-writes, and 16-segment digits with DP can be updated in two byte-writes plus a bit write. Also, discrete LEDs and GPIO port bits can be lit and controlled individually without affecting other ports. Shutdown When the MAX6956 is in shutdown mode, all ports are forced to inputs, and the pullup current sources are turned off. Data in the port and control registers remain unaltered, so port configuration and output levels are restored when the MAX6956 is taken out of shutdown. The display driver can still be programmed while in shutdown mode. For minimum supply current in shutdown mode, logic inputs should be at GND or V+ potential. Shutdown mode is exited by setting the S bit in the configuration register (Table 8). Shutdown mode is temporarily overridden by the display test function.
_______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
INTENSITY TEST CONFIGURATION P4 TO P31 LED DRIVERS OR GPIO INTENSITY REGISTERS TEST REGISTER PORT REGISTERS MASK REGISTER LED DRIVERS AND GPIO PORT CHANGE DETECTOR CONFIGURATION REGISTERS DATA 8 SEGMENT OR GPIO DATA 8 R/W CE R/W
MAX6956
AD0 AD1
ADDRESS MATCHER
COMMAND REGISTER DECODE
7
8
8
DATA BYTE
COMMAND BYTE
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
7 7-BIT DEVICE ADDRESS SDA SCL SLAVE ADDRESS BYTE R/W
TO/FROM DATA REGISTERS
TO COMMAND REGISTERS
DATA BYTE
COMMAND BYTE
Figure 1. MAX6956 Functional Diagram
Serial Interface
Serial Addressing
The MAX6956 operates as a slave that sends and receives data through an I2C-compatible 2-wire interface. The interface uses a serial data line (SDA) and a serial clock line (SCL) to achieve bidirectional communication between master(s) and slave(s). A master (typically a microcontroller) initiates all data transfers to and from the MAX6956, and generates the SCL clock that synchronizes the data transfer (Figure 2). The MAX6956 SDA line operates as both an input and an open-drain output. A pullup resistor, typically 4.7k, is required on SDA. The MAX6956 SCL line operates only as an input. A pullup resistor, typically 4.7k, is required on SCL if there are multiple masters on the 2-
wire interface, or if the master in a single-master system has an open-drain SCL output. Each transmission consists of a START condition (Figure 3) sent by a master, followed by the MAX6956 7-bit slave address plus R/ W bit (Figure 6), a register address byte, one or more data bytes, and finally a STOP condition (Figure 3).
Start and Stop Conditions
Both SCL and SDA remain high when the interface is not busy. A master signals the beginning of a transmission with a START (S) condition by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the slave, it issues a STOP (P) condition by transitioning SDA from low to
_______________________________________________________________________________________________________
7
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
SDA
tBUF tSU, DAT tLOW SCL tHD, DAT tSU, STA tHD, STA tSU, STO
tHIGH tHD, STA tR START CONDITION tF REPEATED START CONDITION STOP CONDITION START CONDITION
Figure 2. 2-Wire Serial Interface Timing Details
SDA
SCL
S START CONDITION
P STOP CONDITION
Figure 3. Standard Stop Conditions
SDA
SCL
DATA LINE STABLE; DATA VALID
CHANGE OF DATA ALLOWED
Figure 4. Bit Transfer
high while SCL is high. The bus is then free for another transmission (Figure 3).
Bit Transfer
One data bit is transferred during each clock pulse. The data on SDA must remain stable while SCL is high (Figure 4).
Acknowledge
The acknowledge bit is a clocked 9th bit, which the recipient uses to handshake receipt of each byte of
8
data (Figure 5). Thus, each byte transferred effectively requires 9 bits. The master generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse, such that the SDA line is stable low during the high period of the clock pulse. When the master is transmitting to the MAX6956, the MAX6956 generates the acknowledge bit because the MAX6956 is the recipient. When the MAX6956 is transmitting to the master, the master generates the acknowledge bit because the master is the recipient.
_______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
START CONDITION SCL 1 2 8 9 CLOCK PULSE FOR ACKNOWLEDGMENT
SDA BY TRANSMITTER
S SDA BY RECEIVER
Figure 5. Acknowledge
SDA 1 MSB SCL 0 0 A3 A2 A1 A0 LSB R/W ACK
Figure 6. Slave Address
Slave Address
The MAX6956 has a 7-bit-long slave address (Figure 6). The eighth bit following the 7-bit slave address is the R/ W bit. It is low for a write command, high for a read command. The first 3 bits (MSBs) of the MAX6956 slave address are always 100. Slave address bits A3, A2, A1, and A0 are selected by address inputs, AD1 and AD0. These two input pins may be connected to GND, V+, SDA, or SCL. The MAX6956 has 16 possible slave addresses (Table 3) and therefore, a maximum of 16 MAX6956 devices may share the same interface.
received, then the MAX6956 takes no further action (Figure 8) beyond storing the command byte. Any bytes received after the command byte are data bytes. The first data byte goes into the internal register of the MAX6956 selected by the command byte (Figure 9). If multiple data bytes are transmitted before a STOP condition is detected, these bytes are generally stored in subsequent MAX6956 internal registers because the command byte address generally autoincrements (Table 4).
Message Format for Reading
The MAX6956 is read using the MAX6956's internally stored command byte as address pointer, the same way the stored command byte is used as address pointer for a write. The pointer generally autoincrements after each data byte is read using the same rules as for a write (Table 4). Thus, a read is initiated by first configuring the MAX6956's command byte by performing a write (Figure 8). The master can now read n consecutive bytes from the MAX6956, with the first data byte being read from the register addressed by the initialized command byte. When performing read-after9
Message Format for Writing the MAX6956
A write to the MAX6956 comprises the transmission of the MAX6956's slave address with the R/ W bit set to zero, followed by at least 1 byte of information. The first byte of information is the command byte. The command byte determines which register of the MAX6956 is to be written by the next byte, if received. If a STOP condition is detected after the command byte is
_______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
7-SEGMENT DIGIT 1 7-SEGMENT DIGIT 2 7-SEGMENT DIGIT 3 7-SEGMENT DIGIT 4 V+
VIRTUAL SEGMENTS P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18 P19 P20 P21 P22 P23 P24 P25 P26 P27 P28 P29 P30 P31
7-SEGMENT DIGIT 5
7-SEGMENT DIGIT 6
7-SEGMENT DIGIT 7
V+
VIRTUAL SEGMENTS P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18 P19 P20 P21 P22 P23 P24 P25 P26 P27 P28 P29 P30 P31
Figure 7. Two MAX6956s Controlling Seven 7-Segment Displays
COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION ACKNOWLEDGE FROM MAX6956 S SLAVE ADDRESS COMMAND BYTE RECEIVED R/W 0 A D15 D14 D13 D12 D11 D10 D9 D8
COMMAND BYTE ACKNOWLEDGE FROM MAX6956
A
P
Figure 8. Command Byte Received
ACKNOWLEDGE FROM MAX6956 HOW COMMAND BYTE AND DATA BYTE MAP INTO MAX6956's REGISTER ACKNOWLEDGE FROM MAX6956 S SLAVE ADDRESS R/W 0 A D15 D14 D13 D12 D11 D10 D9 D8 D7 D6
ACKNOWLEDGE FROM MAX6956 D5 D4 D3 D2 D1 D0
COMMAND BYTE
A
DATA BYTE 1 BYTE
A
P
Figure 9. Command and Single Data Byte Received
10
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
ACKNOWLEDGE FROM MAX6956 HOW COMMAND BYTE AND DATA BYTE MAP INTO MAX6956's REGISTER ACKNOWLEDGE FROM MAX6956 S SLAVE ADDRESS R/W 0 A COMMAND BYTE A DATA BYTE n BYTES AUTOINCREMENT MEMORY WORD ADDRESS A P D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 ACKNOWLEDGE FROM MAX6956 D5 D4 D3 D2 D1 D0
Figure 10. n Data Bytes Received
Table 3. MAX6956 Address Map
PIN CONNECTION AD1 GND GND GND GND V+ V+ V+ V+ SDA SDA SDA SDA SCL SCL SCL SCL AD0 GND V+ SDA SCL GND V+ SDA SCL GND V+ SDA SCL GND V+ SDA SCL A6 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 A5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 DEVICE ADDRESS A3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 A2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 A1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 A0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
Table 4. Autoincrement Rules
COMMAND BYTE ADDRESS RANGE x0000000 to x1111110 x1111111 AUTOINCREMENT BEHAVIOR Command address autoincrements after byte read or written Command address remains at x1111111 after byte written or read
write verification, remember to reset the command byte's address because the stored control byte address generally has been autoincremented after the write (Table 4). Table 5 is the register address map.
Operation with Multiple Masters
If the MAX6956 is operated on a 2-wire interface with multiple masters, a master reading the MAX6956 should use a repeated start between the write, which
sets the MAX6956's address pointer, and the read(s) that takes the data from the location(s). This is because it is possible for master 2 to take over the bus after master 1 has set up the MAX6956's address pointer but before master 1 has read the data. If master 2 subsequently changes, the MAX6956's address pointer, then master 1's delayed read may be from an unexpected location.
______________________________________________________________________________________
11
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 5. Register Address Map
REGISTER No-Op Global Current Configuration Transition Detect Mask Display Test Port Configuration P7, P6, P5, P4 Port Configuration P11, P10, P9, P8 Port Configuration P15, P14, P13, P12 Port Configuration P19, P18, P17, P16 Port Configuration P23, P22, P21, P20 Port Configuration P27, P26, P25, P24 Port Configuration P31, P30, P29, P28 Current054 Current076 Current098 Current0BA Current0DC Current0FE Current110 Current132 Current154 Current176 Current198 Current1BA Current1DC Current1FE Port 0 only (virtual port, no action) Port 1 only (virtual port, no action) Port 2 only (virtual port, no action) Port 3 only (virtual port, no action) Port 4 only Port 5 only Port 6 only Port 7 only Port 8 only Port 9 only Port 10 only COMMAND ADDRESS D15 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X D14 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D13 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 D12 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 D11 0 0 0 0 0 1 1 1 1 1 1 1 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 D10 0 0 1 1 1 0 0 0 1 1 1 1 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 D9 0 1 0 1 1 0 1 1 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 D8 0 0 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 HEX CODE 0x00 0x02 0x04 0x06 0x07 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1A 0x1B 0x1C 0x1D 0x1E 0x1F 0x20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2A
12
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 5. Register Address Map (continued)
REGISTER Port 11 only Port 12 only Port 13 only Port 14 only Port 15 only Port 16 only Port 17 only Port 18 only Port 19 only Port 20 only Port 21 only Port 22 only Port 23 only Port 24 only Port 25 only Port 26 only Port 27 only Port 28 only Port 29 only Port 30 only Port 31 only 4 ports 4-7 (data bits D0-D3) 5 ports 4-8 (data bits D0-D4) 6 ports 4-9 (data bits D0-D5) 7 ports 4-10 (data bits D0-D6) 8 ports 4-11 8 ports 5-12 8 ports 6-13 8 ports 7-14 8 ports 8-15 8 ports 9-16 8 ports 10-17 8 ports 11-18 8 ports 12-19 8 ports 13-20 8 ports 14-21 8 ports 15-22 COMMAND ADDRESS D15 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X D14 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D13 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D12 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D11 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D10 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D9 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D8 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 HEX CODE 0x2B 0x2C 0x2D 0x2E 0x2F 0x30 0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3A 0x3B 0x3C 0x3D 0x3E 0x3F 0x40 0x41 0x42 0x43 0x44 0x45 0x46 0x47 0x48 0x49 0x4A 0x4B 0x4C 0x4D 0x4E 0x4F
______________________________________________________________________________________
13
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 5. Register Address Map (continued)
REGISTER 8 ports 16-23 8 ports 17-24 8 ports 18-25 8 ports 19-26 8 ports 20-27 8 ports 21-28 8 ports 22-29 8 ports 23-30 8 ports 24-31 7 ports 25-31 6 ports 26-31 5 ports 27-31 4 ports 28-31 3 ports 29-31 2 ports 30-31 1 port 31 only COMMAND ADDRESS D15 X X X X X X X X X X X X X X X X D14 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D13 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D12 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D11 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D10 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D9 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D8 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 HEX CODE 0x50 0x51 0x52 0x53 0x54 0x55 0x56 0x57 0x58 0x59 0x5A 0x5B 0x5C 0x5D 0x5E 0x5F
Note: Unused bits read as 0.
Command Address Autoincrementing
Address autoincrementing allows the MAX6956 to be configured with the shortest number of transmissions by minimizing the number of times the command address needs to be sent. The command address stored in the MAX6956 generally increments after each data byte is written or read (Table 4).
12, 13, and 14). Each segment is controlled by a nibble of one of the 16 current registers. Transition (Port Data Change) Detection Port transition detection allows seven maskable ports P24 through P30 to be continuously monitored for changes in their logic status (Figure 11). Enable transition detection by setting the M bit in the configuration register (Table 10) after setting the mask register. If port 31 is configured as an output (Tables 1 and 2), then P31 automatically becomes an interrupt request (IRQ) output to flag detected transitions. Port 31 can be configured and used as a general-purpose input port instead if not being required as the IRQ output. The mask register determines which of the seven ports P24 through P30 are monitored (Table 15). Set the appropriate mask bit to enable that port for transition detect. Clear the mask bit if transitions on that port are to be ignored by the transition detection logic. Ports are monitored regardless of their I/O configuration, both input and output. The MAX6956 maintains an internal 7-bit snapshot register to hold the comparison copy of the logic states of ports P24 through P30. The snapshot register is updated with the condition of P24 through P31 whenever the
Initial Power-Up
On initial power-up, all control registers are reset, the current registers are set to minimum value, and the MAX6956 enters shutdown mode (Table 6). LED Current Control LED segment drive current can be set either globally or individually. Global control simplifies the operation when all LEDs are set to the same current level, because writing just the global current register sets the current for all ports configured as LED segment drivers. It is also possible to individually control the current drive of each LED segment driver. Individual/global brightness control is selected by setting the configuration register I bit (Table 9). The global current register (0x02) data are then ignored, and segment currents are set using register addresses 0x12 through 0x1F (Tables
14
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander
Table 6. Power-Up Configuration
REGISTER FUNCTION Port Register Bits 4 to 31 Global Current Configuration Register Input Mask Register Display Test Port Configuration Port Configuration Port Configuration Port Configuration Port Configuration Port Configuration Port Configuration Current054 Current076 Current098 Current0BA Current0DC Current0FE Current110 Current132 Current154 Current176 Current198 Current1BA Current1DC Current1FE POWER-UP CONDITION ADDRESS CODE (HEX) 0x24 to 0x3F 0x02 REGISTER DATA D7 X X D6 X X D5 X X D4 X X D3 X 0 D2 X 0 D1 X 0 D0 0 0
MAX6956
LED Off; GPIO Output Low 1/16 (minimum on) Shutdown Enabled Current Control = Global Transition Detection Disabled All Clear (Masked Off) Normal Operation P7, P6, P5, P4: GPIO Inputs Without Pullup P11, P10, P9, P8: GPIO Inputs Without Pullup P15, P14, P13, P12: GPIO Inputs Without Pullup P19, P18, P17, P16: GPIO Inputs Without Pullup P23, P22, P21, P20: GPIO Inputs Without Pullup P27, P26, P25, P24: GPIO Inputs Without Pullup P31, P30, P29, P28: GPIO Inputs Without Pullup 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on) 1/16 (minimum on)
0x04
0
0
X
X
X
X
X
0
0x06 0x07 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1A 0x1B 0x1C 0x1D 0x1E 0x1F
X X 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 X 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 X 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 X 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
X = unused bits; if read, zero results. ______________________________________________________________________________________ 15
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 7. Configuration Register Format
FUNCTION Configuration Register ADDRESS CODE (HEX) 0x04 REGISTER DATA D7 M D6 I D5 X D4 X D3 X D2 X D1 X D0 S
Table 8. Shutdown Control (S Data Bit D0) Format
FUNCTION Shutdown Normal Operation ADDRESS CODE (HEX) 0x04 0x04 REGISTER DATA D7 M M D6 I I D5 X X D4 X X D3 X X D2 X X D1 X X D0 0 1
Table 9. Global Current Control (I Data Bit D6) Format
FUNCTION ADDRESS CODE (HEX) D7 Global Constant-current limits for all digits are controlled by one setting in the Global Current register, 0x02 Individual Segment Constant-current limit for each digit is individually controlled by the settings in the Current054 through Current1FE registers D6 D5 REGISTER DATA D4 D3 D2 D1 D0
0x04
M
0
X
X
X
X
X
S
0x04
M
1
X
X
X
X
X
S
Table 10. Transition Detection Control (M-Data Bit D7) Format
FUNCTION Disabled Enabled ADDRESS CODE (HEX) 0x04 0x04 REGISTER DATA D7 0 1 D6 I I D5 X X D4 X X D3 X X D2 X X D1 X X D0 S S
configuration register is written with the M bit set. The update action occurs regardless of the previous state of the M bit so that it is not necessary to clear the M bit and then set it again to update the snapshot register. When the data change detection bit is set, the MAX6956 continuously compares the snapshot register against the states of P24 through P31. When a difference occurs, the IRQ bit (mask register bit D7) is set and IRQ port P31 goes high if it is configured as an output. The IRQ bit and IRQ output remain set until the mask register is next read or written, so if the IRQ is set, then
16
the mask register reads with bit D7 set. Writing the mask register clears the IRQ bit and resets the IRQ output, regardless of the value of bit D7 written.
Display Test Register
Display test mode turns on all ports configured as LED drivers by overriding, but not altering, all controls and port registers, except the port configuration register (Table 16). Only ports configured as LED drivers are affected. Ports configured as GPIO push-pull outputs do not change state. In display test mode, each port's
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 11. Global Segment Current Register Format
LED DRIVE FRACTION 1/16 2/16 3/16 4/16 5/16 6/16 7/16 8/16 9/16 10/16 11/16 12/16 13/16 14/16 15/16 16/16 TYPICAL SEGMENT CURRENT (mA) 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 16.5 18 19.5 21 22.5 24 ADDRESS CODE (HEX) 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 0x02 D7 X X X X X X X X X X X X X X X X D6 X X X X X X X X X X X X X X X X D5 X X X X X X X X X X X X X X X X D4 X X X X X X X X X X X X X X X X D3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 HEX CODE 0xX0 0xX1 0xX2 0xX3 0xX4 0xX5 0xX6 0xX7 0xX8 0xX9 0xXA 0xXB 0xXC 0xXD 0xXE 0xXF
X = Don't care bit.
current is temporarily set to 1/2 the maximum current limit as controlled by RISET. Selecting External Component RISET to Set Maximum Segment Current The MAX6956 uses an external resistor RISET to set the maximum segment current. The recommended value, 39k, sets the maximum current to 24mA, which makes the segment current adjustable from 1.5mA to 24mA in 1.5mA steps. To set a different segment current, use the formula: RISET = 936k / ISEG where ISEG is the desired maximum segment current. The recommended value of RISET is 39k. The recommended value of R ISET is the minimum allowed value, since it sets the display driver to the maximum allowed segment current. RISET can be a higher value to set the segment current to a lower maximum value where desired. The user must also ensure that the maximum current specifications of the LEDs connected to the driver are not exceeded.
The drive current for each segment can be controlled through programming either the Global Current register (Table 11) or Individual Segment Current registers (Tables 12, 13, and 14), according to the setting of the Current Control bit of the Configuration register (Table 9). These registers select the LED's constant-current drive from 16 equal fractions of the maximum segment current. The current difference between successive current steps, ISTEP, is therefore determined by the formula: ISTEP = ISEG / 16 If ISEG = 24mA, then ISTEP = 24mA / 16 = 1.5mA.
Applications Information
Driving Bicolor and Tricolor LEDs
Bicolor digits group a red and a green die together for each display element, so that the element can be lit red, green (or orange), depending on which die (or both) is lit. The MAX6956 allows each segment's current to be set individually from 1/16th (minimum current and LED intensity) to 16/16th (maximum current and LED intensity), as well as off (zero current). Thus, a bicolor (red-green) segment pair can be set to 289 color/intensity combinations. A discrete or CA tricolor
17
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 12. Individual Segment Current Registers
REGISTER FUNCTION Current054 register Current076 register Current098 register Current0BA register Current0DC register Current0FE register Current110 register Current132 register Current154 register Current176 register Current198 register Current1BA register Current1DC register Current1FE register ADDRESS CODE (HEX) 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1A 0x1B 0x1C 0x1D 0x1E 0x1F D7 D6 D5 D4 D3 D2 D1 D0
Segment 5 Segment 7 Segment 9 Segment 11 Segment 13 Segment 15 Segment 17 Segment 19 Segment 21 Segment 23 Segment 25 Segment 27 Segment 29 Segment 31
Segment 4 Segment 6 Segment 8 Segment 10 Segment 12 Segment 14 Segment 16 Segment 18 Segment 20 Segment 22 Segment 24 Segment 26 Segment 28 Segment 30
Table 13. Even Individual Segment Current Format
LED DRIVE FRACTION SEGMENT CONSTANT CURRENT WITH RISET = 39k (mA) 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 16.5 18 19.5 21 22.5 24 ADDRESS CODE (HEX) D7 D6 D5 D4 D3 D2 D1 D0 HEX CODE
1/16 2/16 3/16 4/16 5/16 6/16 7/16 8/16 9/16 10/16 11/16 12/16 13/16 14/16 15/16 16/16
0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F See Table 14.
0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0xX0 0xX1 0xX2 0xX3 0xX4 0xX5 0xX6 0xX7 0xX8 0xX9 0xXA 0xXB 0xXC 0xXD 0xXE 0xXF
18
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 14. Odd Individual Segment Current Format
LED DRIVE FRACTION 1/16 2/16 3/16 4/16 5/16 6/16 7/16 8/16 9/16 10/16 11/16 12/16 13/16 14/16 15/16 16/16 SEGMENT CONSTANT CURRENT WITH RISET = 39k (mA) 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 16.5 18 19.5 21 22.5 24 ADDRESS CODE (HEX) 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F 0x12 to 0x1F D7 D6 D5 D4 D3 D2 D1 D0 HEX CODE
0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 See Table 13.
0x0X 0x1X 0x2X 0x3X 0x4X 0x5X 0x6X 0x7X 0x8X 0x9X 0xAX 0xBX 0xCX 0xDX 0xEX 0xFX
(red-green-yellow or red-green-blue) segment triad can be set to 4913 color/intensity combinations.
Power Dissipation Issues
Each MAX6956 port can sink a current of 24mA into an LED with a 2.4V forward-voltage drop when operated from a supply voltage of at least 3.0V. The minimum voltage drop across the internal LED drivers is therefore (3.0V - 2.4V) = 0.6V. The MAX6956 can sink 28 x 24mA = 672mA when all outputs are operating as LED segment drivers at full current. On a 3.3V supply, a MAX6956 dissipates (3.3V - 2.4V) 672mA = 0.6W when driving 28 of these 2.4V forward-voltage drop LEDs at full current. This dissipation is within the ratings of the 36-pin SSOP package with an ambient temperature up to +98C. If a higher supply voltage is used or the LEDs used have a lower forward-voltage drop than 2.4V, the MAX6956 absorbs a higher voltage, and the MAX6956's power dissipation increases. If the application requires high drive current and high supply voltage, consider adding a series resistor to each LED to drop excessive drive voltage off-chip. For
example, consider the requirement that the MAX6956 must drive LEDs with a 2.0V to 2.4V specified forwardvoltage drop, from an input supply range is 5V 5% with a maximum LED current of 20mA. Minimum input supply voltage is 4.75V. Maximum LED series resistor value is (4.75V - 2.4V - 0.6V)/0.020A = 87.5. We choose 82 2%. Worst-case resistor dissipation is at maximum toleranced resistance, i.e., (0.020A)2 (82 1.02) = 34mW. The maximum MAX6956 dissipation per LED is at maximum input supply voltage, minimum toleranced resistance, minimum toleranced LED forward-voltage drop, i.e., 0.020 x (5.25V - 2.0V - (0.020A 82 x 0.98)) = 32.86mW. Worst-case MAX6956 dissipation is 920mW driving all 28 LEDs at 20mA full current at once, which meets the 941mW dissipation ratings of the 36-pin SSOP package.
Low-Voltage Operation
The MAX6956 operates down to 2V supply voltage (although the sourcing and sinking currents are not guaranteed), providing that the MAX6956 is powered up initially to at least 2.5V to trigger the device's internal reset.
______________________________________________________________________________________
19
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
GPIO INPUT CONDITIONING GPIO/PORT OUTPUT LATCH
GPIO IN
GPIO/PORT OUT IRQ STATUS STORED AS MSB OF MASK REGISTER
P31 IRQ OUTPUT LATCH R S CLOCK PULSE AFTER EACH READ ACCESS TO MASK REGISTER
CONFIGURATION REGISTER M BIT = 1 GPIO INPUT CONDITIONING P30 GPIO/PORT OUTPUT LATCH GPIO INPUT CONDITIONING P29 GPIO/PORT OUTPUT LATCH GPIO INPUT CONDITIONING P28 GPIO/PORT OUTPUT LATCH GPIO IN GPIO IN D GPIO/PORT OUT Q MASK REGISTER BIT 4 GPIO IN GPIO IN D GPIO/PORT OUT Q MASK REGISTER BIT 6
D
Q MASK REGISTER BIT 5
GPIO/PORT OUT
GPIO INPUT CONDITIONING P27 GPIO/PORT OUTPUT LATCH GPIO INPUT CONDITIONING P26 GPIO/PORT OUTPUT LATCH GPIO INPUT CONDITIONING P25 GPIO/PORT OUTPUT LATCH
D
Q MASK REGISTER BIT 3
OR
GPIO/PORT OUT
GPIO IN D GPIO/PORT OUT Q MASK REGISTER BIT 2
GPIO IN
D
Q MASK REGISTER BIT 1
GPIO/PORT OUT
GPIO INPUT CONDITIONING P24 GPIO/PORT OUTPUT LATCH
GPIO IN D GPIO/PORT OUT Q MASK REGISTER LSB CLOCK PULSE WHEN WRITING CONFIGURATION REGISTER WITH M BIT SET
Figure 11. Maskable GPIO Ports P24 Through P31
20
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Table 15. Transition Detection Mask Register
FUNCTION REGISTER ADDRESS (HEX) READ/ WRITE Read 0x06 Write Unchanged REGISTER DATA D7 IRQ Status* D6 Port 30 mask D5 Port 29 mask D4 Port 28 mask D3 Port 27 mask D2 Port 26 mask D1 Port 25 mask D0 Port 24 mask
Mask Register
*IRQ is automatically cleared after it is read.
Table 16. Display Test Register
MODE Normal Operation Display Test Mode ADDRESS CODE (HEX) 0x07 0x07 REGISTER DATA D7 X X D6 X X D5 X X D4 X X D3 X X D2 X X D1 X X D0 0 1
X = Don't care bit
Power-Supply Considerations
The MAX6956 operates with power-supply voltages of 2.5V to 5.5V. Bypass the power supply to GND with a 0.047F capacitor as close to the device as possible. Add a 1F capacitor if the MAX6956 is far away from the board's input bulk decoupling capacitor.
______________________________________________________________________________________
21
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Typical Operating Circuit
3V 3V 36 47nF V+
U1
3 GND 2 GND 1 ISET 39k 35 AD1 4 AD0 33 SDA 34 SCL 31 P31 29 P30 27 P29 25 P28 24 P27 23 P26 22 P25 21 P24
MAX6956AAX
DATA CLOCK
32 P4 30 P5 28 P6 26 P7 5 P8 7 P9 P10 9 11 P11 6 P12 8 P13 10 P14 P15 12 13 P16 14 P17 15 P18 16 P19 P20 17 18 P21 P22 19 20 P23
a1 a2 b c d1 d2 e f g1 g2 h i j k l m dp ca
LED1
a1 a2 b c d1 d2 e f g1 g2 h i 3V 36 47nF 3 GND 2 GND 1 ISET 39k 35 AD1 4 AD0 33 SDA 34 SCL IRQ OUT 31 P31 29 P30 27 P29 25 P28 24 P27 23 P26 22 P25 21 P24 V+ 32 P4 30 P5 28 P6 26 P7 5 P8 7 P9 P10 9 11 P11 6 P12 P13 8 10 P14 P15 12 13 P16 14 P17 15 P18 P19 16 P20 17 18 P21 P22 19 20 P23 j k l m dp ca
LED2
U2
MAX6956AAX
a1 a2 b c d1 d2 e f g1 g2 h i j k l m dp ca
LED3
1
2
SW1
SW2
SW3
22
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander
Pin Configurations (continued)
TOP VIEW
ISET 1 GND 2 GND 3 AD0 4 P8 5 P12 6 P9 7 P13 8 P10 9 P14 10 P11 11 P15 12 P16 13 P17 14 P18 15 P19 16 P20 17 P21 18 36 V+ 35 AD1
MAX6956
GND GND
GND
ISET V+
34 SCL 33 SDA 32 P4
40
39
38
37
36
35
34
33
32
MAX6956
31
N.C.
AD1 SCL SDA
AD0
31 P31 30 P5 29 P30 28 P6 27 P29 26 P7 25 P28 24 P27 23 P26 22 P25 21 P24 20 P23 19 P22
P8 P12 P9 P13 P10 P14 P11 P15 P16 P17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
30 29 28 27 26
P4 P31 P5 P30 P6 P29 P7 P28 P27 P26
MAX6956
25 24 23 22 21
N.C.
QFN
SSOP
Chip Information
TRANSISTOR COUNT: 33,559 PROCESS: CMOS
______________________________________________________________________________________
P25 N.C.
P18 P19
P20 P21 P22 P23
P24
23
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
SSOP.EPS
2
1
INCHES DIM A A1 B C E H D E e H L MIN 0.068 0.002 0.010 MAX 0.078 0.008 0.015
MILLIMETERS MIN 1.73 0.05 0.25 MAX 1.99 0.21 0.38 D D D D D INCHES MIN 0.239 0.239 0.278 0.317 0.397 MAX 0.249 0.249 0.289 0.328 0.407 MILLIMETERS MIN 6.07 6.07 7.07 8.07 10.07 MAX 6.33 6.33 7.33 8.33 10.33 N 14L 16L 20L 24L 28L
0.20 0.09 0.004 0.008 SEE VARIATIONS 0.205 0.301 0.025 0 0.212 0.311 0.037 8 5.20 7.65 0.63 0 5.38 7.90 0.95 8 0.0256 BSC 0.65 BSC
N
A C B e D A1 L
NOTES: 1. D&E DO NOT INCLUDE MOLD FLASH. 2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006"). 3. CONTROLLING DIMENSION: MILLIMETERS. 4. MEETS JEDEC MO150. 5. LEADS TO BE COPLANAR WITHIN 0.10 MM.
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, SSOP, 5.3 MM
APPROVAL DOCUMENT CONTROL NO. REV.
21-0056
1 1
C
24
______________________________________________________________________________________
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
SSOP.EPS
REV.
36
INCHES DIM A A1 B C e E H L D MAX MIN 0.104 0.096 0.011 0.004 0.017 0.012 0.009 0.013 0.0315 BSC 0.291 0.299 0.398 0.414 0.040 0.020 0.598 0.612
MILLIMETERS MAX MIN 2.44 2.65 0.10 0.29 0.30 0.44 0.23 0.32 0.80 BSC 7.40 7.60 10.11 10.51 0.51 15.20 1.02 15.55
E
H
1
TOP VIEW
D A1 e A
C 0-8
B
L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 36L SSOP, 0.80 MM PITCH
APPROVAL DOCUMENT CONTROL NO.
21-0040
E
1 1
______________________________________________________________________________________
25
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander MAX6956
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
D2 D D/2 k
C L
b D2/2
E/2 E2/2 E (NE-1) X e
C L
E2
k
e (ND-1) X e
L
C L
C L
L
L
e
e
A1
A2
A
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE 36, 40L QFN THIN, 6x6x0.8 mm
DOCUMENT CONTROL NO. REV.
APPROVAL
21-0141
1 2
B
26
______________________________________________________________________________________
QFN THIN 6x6x0.8.EPS
2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
MAX6956
COMMON DIMENSIONS
PKG. CODES T3666-1 T4066-1
EXPOSED PAD VARIATIONS
D2 E2 MIN. NOM. MAX. MIN. NOM. MAX. 3.60 4.00 3.70 4.10 3.80 4.20 3.60 4.00 3.70 4.10 3.80 4.20
NOTES: 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
PROPRIETARY INFORMATION
9. DRAWING CONFORMS TO JEDEC MO220. 10. WARPAGE SHALL NOT EXCEED 0.10 mm.
TITLE:
PACKAGE OUTLINE 36, 40L QFN THIN, 6x6x0.8 mm
DOCUMENT CONTROL NO. REV.
APPROVAL
21-0141
2 2
B
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 27 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX6956

	To Download MAX6956 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .