View PAM2701_4240553.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

PAM2701
4-Channel Regulated Charge Pump White LED Driver Features
n n n n n n n n n n n
Description
The PAM2701 is a 4-channel charge pump white LED driver, capable of driving up to 4 LEDs in parallel. The device operates in either 1x mode or 1.5x fractional mode, and it can switch from 1x mode to 1.5x mode automatically when the input voltage decreased. Its internal 4 current sink regulators ensure both the LED current matching and the brightness uniformity. The LED current can be programmed by an external resistor, R SET, connected between the RSET pin and ground. LED current of up to 30mA are supported by the input supply voltage over a range of 2.7V to 5.5V, making the device optimized for Li-Ion battery applications. The PAM2701 has a fixed switching frequency of 1MHz, allowing the use of very small value ceramic capacitors. The enable input pin allows the device to be set in shutdown mode, and the current consumption is reduced to less than 1A. LED dimming can be done by several methods including using a DC voltage to set the RSET pin current, adding a switched resistor in parallel with R SET, or applying a PWM signal to CTRx pin or EN pin.
Peak Efficiency: 90% Individual Current Regulation 3-bit Digital Output Control Two modes of operation:1x and 1.5x Current Matching with a Max Tolerance of 3% Output Current up to 30mA per LED Total LED Current up to 4*30mA=120mA Fixed Frequency of 1MHz Open LED Protection Space Saving Package QFN 3mmx3mm and QFN 4mmx4mm Pb-Free Package
Applications
n n n n n n n n
Cellular Phones LED Backlighting LCD Modules Handheld Devices Digital Cameras PDAs PMPs MP3 Players
Typical Application
1F 1F
8 7
EN C IN 1F Control 0 Control 1 Control 2
R SET 24k
C1 + VIN
9
11
10
C2 -
C1 - C2 +
6
Co 1F
VOUT
1 EN PAM2701
V IN
2 3 4 5
CTR0 CTR1 CTR2 RSET GND
LED1 LED2 LED3 LED4
16 15 14 13
20mA
12
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
1
PAM2701
4-Channel Regulated Charge Pump White LED Driver Block Diagram
C1 1F 1F C1 + C2 C2 +
VIN C IN 1F
1x Mode ( LDO ) 1 . 5x Charge Pump
VOUT CO 1F
1MHz Oscillator
Mode Control
LED1 LED2
EN
1 . 2V Ref RSET R SET 24K
LED3 LED4
20mA
Current Setting
CTR0 CTR1 CTR2
LED Output
4 Current Sink Regulators
Select
Table 1:LED Enable Logic
Control Lines CTR2 0 0 0 0 1 1 1 1 CTR1 0 0 1 1 0 0 1 1 CTR0 0 1 0 1 0 1 0 1 LED4 ON ON LED Outputs LED3 ON ON ON LED2 ON ON ON ON LED1 ON ON ON ON -
Note:1=logic high(or V IN) 0=logic low(or GND) - =LED output off
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
2
PAM2701
4-Channel Regulated Charge Pump White LED Driver Pin Configuration & Marking Information
QFN 3mmx3mm/4mmx4mm
16 15 1 2 3 4 5
Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
14
13 12
P2701 XAT YW
11 10 9
X: Internal Code A: Assembly Code T: Testing Code Y: Year W: Week
6
7
8
Function Enable Input, Active High Digital Control Input 0 Digital Control Input 1 Digital Control Input 2 Set Resistance Charge pump output connected to the LED anodes Supply Voltage Bucket Capacitor 1 Terminal Bucket Capacitor 1 Terminal Bucket Capacitor 2 Terminal Bucket Capacitor 2 Terminal Ground Reference LED4 Cathode Terminal LED3 Cathode Terminal LED2 Cathode Terminal LED1 Cathode Terminal
Name EN CTR0 CTR1 CTR2 RSET VOUT VIN C1+ C1C2C2+ GND LED4 LED3 LED2 LED1
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
3
PAM2701
4-Channel Regulated Charge Pump White LED Driver Absolute Maximum Ratings
These are stress ratings only and functional operation is not implied . Exposure to absolute maximum ratings for prolonged time periods may affect device reliability . All voltages are with respect to ground . VIN , VOUT , LEDx Pin Voltage.........- 0.3V to 6.6V EN , CTRx Pin Voltage.......................- 0.3V to V IN RSET Pin Voltage............................. .-0.3V to V IN Ambient Temperature Range........- 40 C to 85 C Storage Temperature Range.........-65C to 150C Lead Temperature......................................300 C ESD Ratings Human Body Model ( HBM).........................2000V
Recommended Operating Conditions
V IN...................................................2.7V to 5.5V Max. Supply Voltage (for Max. duration of 30 minutes)................................................6.4V Input/Output/Bucket Capacitors....120%F(TYP.) Ambient Temperature.....................-40 C to 85 C I LED per LED...................................0mA to 30mA
Thermal Information
Parameter Thermal Resistance (Junction to Ambient) Power DissipationPD @TA =25 Symbol JA PD Package QFN 3*3mm QFN 4*4mm QFN 3*3mm QFN 4*4mm Maximum 34 25 2.9 4.0 Unit C/W W
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
4
PAM2701
4-Channel Regulated Charge Pump White LED Driver Electrical Characteristic
Parameter Input Voltage Range Shutdown Current Quiescent Current RSET Regulated Voltage Programmed LED Current LED Current Accuracy LED Channel Matching Output Resistance (Open Loop) Charge Pump Frequency V IN at Mode Transition from 1x to 1.5x 1x to 1.5x Mode Transition Dropout Delay Input Leakage Current High Detect Threshold Low Detect Threshold T DROP IEN-CTR V EN-CTRH V EN-CTRL On Inputs EN,CTR0,1&2 On Inputs EN,CTR0,1&2 On Inputs EN,CTR0,1&2 1.5 0.4
T A= 25 C , V IN= 3.5V, C IN=C O=1F, unless otherwise noted.
Symbol V IN ISD IQ VRSET RSET =90k ILED ILED-A CC ILED-DEV RO fOSC V IN-Tran ILED =15mA ILED =20mA (ILED-ILEDAVG)/ILEDAVG 1x Mode, IO=100mA 1.5x Mode, IO=100mA RSET =29.3k RSET =14.7k VEN =0V Shutdown Mode 1x Mode, No Load 1.5x Mode, No Load 1.19 Conditions Min 2.7 0.05 0.6 2.5 1.23 5.0 15.0 30.0 5 3 1.7 4.3 1.0 3.45 3.60 10 1 Typ Max 5.5 1 1.2 5 1.25 Unit V A mA mA V mA mA mA % % MHz V V s A V V
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
5
PAM2701
4-Channel Regulated Charge Pump White LED Driver Typical Characteristics
V IN = 3.6V, EN = V IN, R SET = 24k, C IN=C O=1F,T A = 25C, unless otherwise noted. 2. Efficiency vs Output Current (4 LEDs) 1. Efficiency vs Input Voltage (4 LEDs)
100 90
100 90
Efficiency (%)
80 70 60 50 40 2.4 3 3.6 4.2 4.8 5.4 Input Voltage (V) 15mA per LED 20mA per LED
Efficiency (%)
80 70 60 50 40 10 40 70 100 130 160 Output Current (mA) VIN=3.2V VIN=4.2V
24 22 20 18 16 14 12 10
3. LED Current vs Input Voltage (4 LEDs)
4. Supply Current vs Input Voltage (4 LEDs)
140 120
Supply Current (mA)
LED Current (mA)
20mA per LED
100 80 60 40 20 0
20mA per LED
15mA per LED
15mA per LED
2.8
3.1
3.4
3.7
4
4.3
2.4
3
3.6
4.2
4.8
5.4
Input Voltage (V)
Input Voltage (V)
3.00
5. Ground Current vs Input Voltage
Oscillator Frequency (MHz)
1.1
6. Oscillator Frequency vs Input Voltage
Ground Current (mA)
2.50 2.00 1.5X Mode 1.50 1.00 0.50 0.00 2.8 3.1 3.4 3.7 4 4.3 Input Voltage (V) 1X Mode
1.05
1
0.95
0.9 2.8 3.2 3.6 Input Voltage (V) 4 4.4
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
6
PAM2701
4-Channel Regulated Charge Pump White LED Driver Typical Characteristics
7 6
7. Output Voltage vs Input Voltage
1.5X Mode
4.5 4
8. Output Resistance vs Input Voltage
5 4 3 2 1 0 2.8 3.1 3.4 3.7 4 4.3 Input Voltage (V) 1X Mode
Output Resitance ()
Output Voltage (V)
3.5 3 2.5 2 1.5 1 2.8 3.1 3.4 3.7 4 4.3 Input Voltage (V) 1.5X ModeIO=100mA
1X ModeIO=100mA
9. LED Current Setting Using the External Resistor R SET LED Current vs R SET Resistance
35 30 25 20 15 10 5 0 0 100 200 300 400 500 600
R SET RSET Resistance (K)
10.LED Current Setting Using a DC Voltage to RSET Pin LED Current vs Analog Control Voltage
35 30
LED Current (mA)
LED Current (mA)
25 20 15 10 5 0 0 0.3 0.6 0.9 1.2 Analog Control Voltage (V)
11.LED Current Setting Using a PWM Signal to EN Pin
35 30
LED Current vs Duty Cycle @ f=100Hz
35 30
LED Current vs Duty Cycle @ f=1KHz
LED Current (mA)
LED Current (mA)
25 20 15 10 5 0 0
VIN=3.2V
25 20 15 10 5 0
VIN=3.2V
VIN=4.2V
VIN=4.2V
20
40
60
80
100
0
20
40
60
80
100
PWM Duty Cycle (%)
PWM Duty Cycle (%)
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
7
PAM2701
4-Channel Regulated Charge Pump White LED Driver Typical Characteristics
12.LED Current Setting Using a PWM Signal to CTR0 Pin LED Current vs Duty Cycle @ f=100HZ LED Current vs Duty Cycle @ f=1KHZ
VIN=3.2V
35 30 LED Current (mA)
35 30
LED Current (mA)
VIN=3.2V 25 20 15 10 5 0 0 20 40 60 80 100 PWM Duty Cycle (%) VIN=4.2V
25 20 15 10 5 0 0 20 40 60 80 100 PWM Duty Cycle (%) VIN=4.2V
13.Output Ripple 1X Mode 1.5X Mode
Vin AC Coupling Iin AC Coupling Vo AC Coupling
Vin AC Coupling Iin AC Coupling Vo AC Coupling
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
8
PAM2701
4-Channel Regulated Charge Pump White LED Driver Application Information
Detailed Description
As shown in the block diagram on page 2, the main components within the PAM2701 include a fractional charge pump, mode selection circuit, output selection logic, LED current setting detection circuit, and 4 current sense circuits. The fractional charge pump multiplies the input voltage a multiple of 1X and 1.5X times the input voltage. The charge pump switches at a fixed 1MHz when the mode is 1.5X. The charge pump does not switch during 1X mode, saving power and improving efficiency. The mode selection circuit automatically selects the mode as 1X or 1.5X based on circuit conditions such as LED voltage, input voltage and load current. 1X is the more efficient mode than 1.5X mode. Table 1 on page 2 shows the output selection logic control over the LED outputs for on and off functions with 8 different output states. The current set and detection circuit uses an external resistor and a 1.20V reference to program the LED current. 4 current regulating circuits sink matched currents from the LEDs. LEDs with matched forward voltage will produce the best possible matched currents. For best matching performance it is recommended that the Vf between LEDs be under 250mV. The unused LED channels can be turned off by CTR0, CTR1 and CTR2, and connecting the respective LED pins to VOUT pin, in which case, the corresponding LED driver sink current is only about 20 A. The most basic means of setting the LED current is connecting a resistor from R SET to GND, as shown in the application circuit on Page 1. The resistor R SET establishes the reference current needed for a constant LED current. Values of R SET for a fixed LED current are given in Table 2, "Typical R SET Resistance vs. LED Current". Table 2: R SET Resistance Selection
ILED(mA) 30 20 15 10 9 8 7 6 5 4 3 2 1 RSET(k) 14.7 21.8 29.3 44.1 49.4 55.7 64.2 75.0 90.0 114.2 156.5 238.0 540.0 Standard Value (k) 14.7 22.0 29.4 44.2 49.9 56.0 63.4 75.0 88.7 115.0 158.0 237.0 536.0 Value % Difference 0..0% 0.9% 0.3% 0.2% 1.0% 0.5% 0.3% 0.0% -0.3% 0.7% 0.9% -0.4% -0.7%
Method 2: LED Current Setting with a DC Voltage to RSET Pin Method 2 is for setting the LED current to control brightness. An example circuit is shown in Figure 1, employing a 14.7k resistor and an analog input DC voltage, V SET, which varies from 1.2V to 0V to control LED current from 1mA to 30mA. Table 3 shows the resulting output. If necessary, the analog V SET voltage can be sourced from a voltage higher than 1.20V, but the source must be divided down so that the V SET mode will not exceed 1.20V. For lower current and higher resolution applications , a larger resistor may be used instead. PWM applications are also possible with this circuit by application of RC filtering (Consult with PAM for detail application support).
Methods for Setting LED Current
There are 4 methods for setting and adjusting the LED current outlined here. The methods are: 1) R SET only 2) Analog Reference V SET 3) PWM Input at CTR0 4) PWM Input at EN Method 1: LED Current Setting with an External Resistor R SET
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
9
PAM2701
4-Channel Regulated Charge Pump White LED Driver Application Information
Table 3: Analog Voltage for LED Current Control
VSET(V) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 ILED(mA) 30.0 27.7 25.3 22.9 20.5 18.1 15.7
VIN
Figure 2: PWM Signal at CTR0 pin for LED Current Control
Co 1.0 F
VSET(V) 0.7 0.8 0.9 1.0 1.1 1.2
ILED(mA) 13.3 10.9 8.4 6.0 3.6 1.1
100Hz to 1kHz
D1
D2
D3
D4
LED1 LED2 LED3 LED4 EN
PWM
GND C2+
CTR0
PAM2701
CTR1 C2-
C2 1.0 F
CTR2 RSET VOUT VIN R SET 14.7k C1+
C1-
C1 1.0 F Cin 1.0 F
Figure 1: Analog Voltage for LED Current Control
Method 4: LED Current Setting with a PWM Signal to EN Pin
Co 1.0F LED1 EN CTR0 D1 D2 D3 D4 LED2 LED3 LED4 GND
C2+
PAM2701
CTR1 C2-
C2 1.0F
CTR2 RSET VOUT VIN C1+
RSET 14.7 k VSET VIN Cin 1.0F
1.0F
Method 3: LED Current Setting with a PWM Signal to CTRx Pin In circuit in Figure 2 four LEDs are turned on and off by a PWM signal on the CTR0. A resistor R SET is used to set the on state current and the average LED current is then proportional to the percentage of on-time when the CTR0 pin is logic low. Average LED current is approximately equal to: I AVG = (t ON*I LED_ON)/ (t ON + t OFF) It is recommended that PWM frequency is between 100Hz and 1kHz. Due to start up delay and ramp up time, frequency >1kHz will result in error in the average value of I LED. Frequency <100Hz can cause the LEDs to blink visibly.
The four LEDs are turned on and off by applying a PWM signal to the EN pin in circuit in Figure 3. The circuit is the same as one in method 3, using a resistor R SET to set the on state current and the average LED current proportional to the percentage of on-time when the EN pin is logic low. Average LED current is approximately equal to: I AVG = (t ON*I LED_ON)/ (t ON + t OFF) Similarly, it is recommended that PWM frequency is between 100Hz and 1kHz. Due to start up delay and ramp up time, frequency >1kHz will result in error in the average value of I LED. Frequency <100Hz can cause the LEDs to blink visibly
Figure 3: PWM Signal at EN pin for LED Current Control
Co 1.0 F
D1
D2
D3
D4
100Hz to 1kHz
LED1 EN CTR0
LED2 LED3
LED4 GND
PWM
C2+
PAM2701
CTR1 C2C1C1+ C1 R SET 14.7k Cin 1.0 F 1.0 F
C2 1.0 F
CTR2 RSET VOUT VIN
VIN
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
10
PAM2701
4-Channel Regulated Charge Pump White LED Driver Application Information
PCB Layout When the driver is in the 1.5X charge pump mode, the 1MHz switching frequency operation requires to minimize the trace length and impedance to ground on all 4 capacitors. A ground plane should cover the area on the bottom side of the PCB opposite to the IC and the bypass capacitors. Capacitors C IN and Co should be short connected to ground with multiple vias as shown on Figure4. Square copper area matches the QFN 16 exposed pad (GND) which is connected by a trace to the pin 12 pad (GND). A large via (metalized hole) centered in the square pad provides a low impedance connection to the ground plane on the opposite side of the PCB and allows the heat dissipation of the LED driver to achieve excellent thermal performance. Figure 4: PCB layout
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
11
PAM2701
4-Channel Regulated Charge Pump White LED Driver Ordering Information
PAM2701 X X X
Shipping Package Pin Number Package Type
Package Type J: QFN 3mmx3mm K: QFN 4mmx4mm Pin Number E: 16 Shipping Package R: Tape & Reel
Part Number PAM2701JER PAM2701KER
Package Type Thin QFN-16 3mmx3mm Thin QFN-16 4mmx4mm
MOQ 3,000 Units/Tape & Reel 3,000 Units/Tape & Reel
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
12
PAM2701
4-Channel Regulated Charge Pump White LED Driver Outline Dimension
3x3 mm TQFN 16
DIMENSIONS (Millieters) MIN A A1 A2 b D D1 E E1 e L N aaa bbb 0.30 0.18 2.90 1.55 2.90 1.55 0.70 0.00 TYP 0.75 0.02 0.20 0.25 3.00 1.70 3.00 1.70 0.50BSC 0.40 16 0.08 0.10 0.50 0.30 3.10 1.80 3.10 1.80 MAX 0.80 0.05
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
13
PAM2701
4-Channel Regulated Charge Pump White LED Driver Outline Dimension 4x4mm QFN 16
DIMENSIONS (Millieters) MIN A A1 A2 b D D1 E E1 e L N aaa bbb 0.45 0.25 3.90 2.00 3.90 2.00 0.80 0.00 TYP 0.90 0.02 0.20 0.30 4.00 2.15 4.00 2.15 0.65BSC 0.55 16 0.08 0.10 0.65 0.35 4.10 2.25 4.10 2.25 MAX 1.00 0.05
Power Analog Microelectronics , Inc
www.poweranalog.com 09/2008 Rev 1.3
14

▲Up To Search▲

Price & Availability of PAM2701

	To Download PAM2701 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .