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LTC1145/LTC1146 Low Power Digital Isolator
FEATURES
s s
DESCRIPTIO
s
s s s
UL Recognized (R) (LTC1145A, LTC1146A) File E151738 to UL1577 Low Input Current LTC1145: 700A LTC1146: 70A Maximum Input Frequency LTC1145: 200kHz LTC1146: 20kHz TTL Level Output Noise Filter Prevents Glitches at the Output Output Can Be Synchronized to an External Clock
The LTC1145A/LTC1146A provide 2500VRMS (1minute) or 3000VRMS (1 second) of input to output isolation for TTL digital/CMOS signals. The LTC1145/LTC1146 are intended for less stringent applications and are rated for 500VRMS. Unlike opto-isolators, the input current is a mere 70A for the LTC1146 which can handle frequencies up to 20kHz. The faster LTC1145 will handle frequencies up to 200kHz while only drawing 700A. The output signal is in phase with the input and swings between GND2 and VCC providing a TTL/CMOS compatible signal without any pull-up resistors. An on-chip noise filter helps prevent glitches and data errors at the output, and a pin is provided for synchronizing the output signal to an external system clock. IC Innovation of the Year Winner
APPLICATIO S
s s s
Low Power Opto-Isolator Replacement Isolated Serial Data Interfaces Isolated Power MOSFET Drivers
TYPICAL APPLICATIO
Digital Isolation Interface Data Rate Up to 200kHz
DATA 5V IN 0 f1 = 100kHz 1 18
LTC1145 Typical Waveforms
DIN
GND1
ISOLATION BARRIER 7 8 9 LTC1145 NC OSCIN GND2 VCC OSOUT DOUT 5V 12 11 10 DATA OUT
OSOUT DIN
LTC1145/46 * TA01
DOUT
OSOUT AND DOUT LOADED WITH 15pF SCOPE PROBE
U
LTC1145/6 * TA02
U
U
1
LTC1145/LTC1146 ABSOLUTE AXI U RATI GS
Operating Temperature Range ................... 0C to 70C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
Supply Voltage ....................................................... 12V Input Voltage DIN .................................................... 11V to (GND1 - 0.3V) OSCIN ............................. (VCC + 0.3V) to (GND2 - 0.3V) Output Voltage OSOUT, DOUT ................ (VCC + 0.3V) to (GND2 - 0.3V)
PACKAGE/ORDER I FOR ATIO
TOP VIEW DIN 1 ISOLATION BARRIER 18 GND1
ORDER PART NUMBER LTC1145CN LTC1145ACN
NC OSCIN GND2
7 8 9
12 VCC 11 OSOUT 10 DOUT
N PACKAGE 18-LEAD PLASTIC DIP
TJMAX = 125C, JA = 110C/W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL LTC1145 VOL VOH VIL VIH IIN Output Low Voltage Output High Voltage External Frequency Input Low Voltage External Frequency Input High Voltage Input Current PARAMETER
VCC = 5V, TA = 25C unless otherwise noted.
MIN
q q q q q q q q q q q q q
CONDITIONS OSOUT, DOUT at 4mA OSOUT, DOUT at 4mA OSCIN OSCIN OSCIN at 5V DIN at 3V DIN at 5V DIN at 10V OSCIN = 0V CL = 15pF CL = 15pF CL = 15pF CL = 15pF DIN DIN = GND1 Connected to VCM DIN DIN 1 Minute (Note 2) 1 Second
q q
ICC tPLH1 tPHL1 tPLH2 tPHL2 SR CMSR VINH VINL VISO
Supply Current DIN to OSOUT, Low to High DIN to OSOUT, High to Low DIN to DOUT, Low to High DIN to DOUT, High to Low Input Signal Slew Rate Common-Mode Slew Rate (Note 1) Input High Voltage Input Low Voltage Isolation Voltage, LTC1145A
2
U
U
W
WW
U
W
TOP VIEW DIN 1 ISOLATION BARRIER 18 GND1
ORDER PART NUMBER LTC1146CN LTC1146ACN
NC CEXT GND2
7 8 9
12 VCC 11 OSOUT 10 DOUT
N PACKAGE 18-LEAD PLASTIC DIP
TJMAX = 125C, JA = 110C/W
TYP
MAX 0.4
UNITS V V V V A mA mA mA mA s s s s V/s V/s V V VRMS VRMS
3.5 0.8 2.4 0.45 0.70 1.85 2 0.2 0.4 0.7 1.1 1 1000 3 0.8 2500 3000 10.0 0.65 1.30 3.20 3.5 0.7 1.1 1.5 2
LTC1145/LTC1146
ELECTRICAL CHARACTERISTICS
SYMBOL LTC1146 VOL VOH VIL VIH IIN Output Low Voltage Output High Voltage Input Low Voltage Input High Voltage Input Current PARAMETER
VCC = 5V, TA = 25C unless otherwise noted.
MIN
q q q q q q q q q q q q
CONDITIONS OSOUT, DOUT at 4mA OSOUT, DOUT at 4mA DIN DIN DIN at 3V DIN at 5V DIN at 10V VCC = 5V CL = 15pF CL = 15pF CL = 15pF, CEXT = 50pF CL = 15pF, CEXT = 50pF DIN DIN = GND1 Connected to VCM 1 Minute (Note 2) 1 Second
TYP
MAX 0.4
UNITS V V V V A A A mA s s s s V/s V/s VRMS VRMS
3.5 0.8 3 40 70 225 1.8 0.5 6 5 10 1 1000 2500 3000 80 120 350 3 1.5 11 10 18
ICC tPLH1 tPHL1 tPLH2 tPHL2 SR CMSR VISO
Supply Current DIN to OSOUT, Low to High DIN to OSOUT, High to Low DIN to DOUT, Low to High DIN to DOUT, High to Low Input Signal Slew Rate Common-Mode Slew Rate (Note 1) Isolation Voltage, LTC1146A
The q denotes specifications which apply over the operating temperature range.
Note 1: Pins 1 and 18 are connected together. Pins 7 through 12 are connected together. Note 2: Value derived from 1 second test.
TYPICAL PERFOR A CE CHARACTERISTICS
Output High Voltage (DOUT and OSOUT) vs Temperature
I = 4mA 4.6 0.4
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
4.5
0.3
INPUT CURRENT (A)
4.4
4.3
4.2 -50
-25
75 0 50 25 TEMPERATURE (C)
LTC1145/6 * TPC01
UW
100 125
Output Low Voltage (DOUT and OSOUT) vs Temperature
270
LTC1146 Input Current vs Input Voltage
240 210 180 150 120 90 60 30 TA = 25C
I = 4mA
0.2
0.1
0 -50
-25
75 0 50 25 TEMPERATURE (C)
100
125
0 3 4 5 67 8 9 10 INPUT VOLTAGE (V) 11 12
LTC1145/6 * TPC01
LTC1145/6 * TPC03
3
LTC1145/LTC1146
TYPICAL PERFOR A CE CHARACTERISTICS
LTC1145 Input Current vs Input Voltage
2.2 2.0 1.8 TA = 25C
SUPPLY CURRENT (mA)
INPUT CURRENT (mA)
1.6 1.4 1.2 1.0 0.8 0.6 0.4 3 4 5 67 8 9 10 INPUT VOLTAGE (V) 11 12
LTC1146 Input Current vs Temperature
90
INPUT CURRENT (A)
VIN = 5V
80
INPUT CURRENT (A)
70
60
50 -50
-25
75 0 50 25 TEMPERATURE (C)
4
UW
LTC1145/LTC1146 Supply Current vs Temperature
2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 -50 -25 50 0 25 75 TEMPERATURE (C) 100 125 LTC1146 LTC1145 VIN = 0V VCC = 5V
LTC1145/6 * TPC04
LTC1145/6 * TPC05
LTC1145 Input Current vs Temperature
900 VIN = 5V
800
700
600
100
125
500 -50
-25
75 0 50 25 TEMPERATURE (C)
100
125
LTC1145/6 * TPC06
LTC1145/6 * TPC06
LTC1145/LTC1146
PI FU CTIO S
Pin 1 (DIN): Data Input Pin 7 (NC): Not Connected Pin 8 (LTC1145 OSCIN): External Frequency Input. The signal on this pin overrides the internal oscillator frequency. Pin 8 (LTC1146 CEXT): External Capacitor. Connecting a capacitor at this pin allows the internal oscillator frequency to be slowed down. Pin 9 (GND2): The Ground Connection of the Receiver Die. Pin 10 (DOUT): Data Output. The output signal has gone through the internal filter. The output level is TTL compatible. Pin 11 (OSOUT): One-Shot Output. The output signal that does not go through the internal filter. The output level is TTL compatible. Pin 12 (VCC): Positive Supply of the Receiver Die, 4.5V < VCC < 5.5V. Pin 18 (GND1): The Ground Connection of the Driver Die.
SWITCHI G TI E WAVEFOR S
5V DIN 0V tPLH1 OSOUT 0V 1.5V tPLH2 DOUT 0V 1.5V tPHL1 1.5V tPHL2 1.5V
LTC1145/46 * WF01
1.5V
FU CTIO AL DIAGRA S
LTC1145
DIE #1 VCC 12 A C OSCILLATOR B D DIE #2 TTL BUFFER 11 ONE SHOT OUTPUT E D Q F 18 GND1 9 GND2 ISOLATION BARRIER OSCILLATOR CD CD Q 8 EXT OSC IN OUT FILTER TTL BUFFER 10 DATA OUTPUT
DATA 1 INPUT
W
W
W
U
U
U
U
U
U
tr = tf = 20ns
1.5V
+ -
ONE-SHOT
CLOCK DETECTOR
LTC1145/46 * FD01
5
LTC1145/LTC1146
FU CTIO AL DIAGRA S
LTC1146
DIE #1 VCC 12 A C OSCILLATOR B D DIE #2 TTL BUFFER 11 ONE-SHOT OUTPUT DATA OUTPUT
DATA 1 INPUT
18 GND1
ISOLATION BARRIER
OPERATIO
Basic Functionality The LTC1145/LTC1146 consist of two separate die (see Functional Diagram) and two internal 1pF capacitors which provide isolation. Die #1 contains a low power oscillator and two low power drivers. The supply current for the oscillator and drivers comes from the digital input. When the digital input exceeds 3V, the oscillator turns on and provides a 4MHz square wave to the drivers (400kHz for the LTC1146). The drivers pass the signal through the isolation capacitors and form a differential signal at the input to the comparator (points C and D) on die #2. As soon as the comparator output changes state in either direction, the one-shot output (OS) goes high. The time constant of the one-shot is set to 2 times the oscillation period, so the one-shot output will stay high as long as the oscillation continues. When the digital input goes low, the
6
W
U
U
U
+
E D Q F IN OUT FILTER TTL BUFFER 10
-
ONE-SHOT
9 GND2 OSCILLATOR CEXT 8
LTC1145/46 * FD02
EXT CAPACITOR
oscillator on die #1 turns off and the one-shot output resets low. To increase the noise immunity of the system, a filter is added to die #2. The filter is basically a binary counter clocked by either an internal free running oscillator or external oscillator. A clock detector circuit disconnects the internal oscillator from the filter and connects the external oscillator after detecting three pulses on the OSCIN pin. The frequency of the internal free running oscillator on die #2 is designed to match the frequency of the gated oscillator on die #1, but the two oscillators are not synchronized. For the digital output (DOUT) to go high, the filter must count four consecutive clock cycles with the one-shot output remaining high. For the digital output to go low, the filter must count four consecutive clock cycles with the one-shot output remaining low.
LTC1145/LTC1146
OPERATIO
DIN
A
B
C
D
E
OS
F
DOUT NOTE: THE SHADED AREA AT DOUT IS THE OUTPUT JITTER DUE TO THE TWO OSCILLATORS NOT SYNCHRONIZED. REFER TO FUNCTIONAL DIAGRAMS.
Noise and Glitch Immunity As an example, assume that the digital input is low and the oscillator on die #1 is off. There is a very large fast rising common-mode signal at the ground and input pins to die #1 with respect to the ground of die #2. Any mismatch in the internal capacitors will convert the common-mode signal into a differential glitch at the inputs to the comparator. The output of the comparator will toggle and the output of the one-shot will go high. However, the filter will only count one clock cycle before the output of the one-shot resets, so the digital output will remain low. The filter works as long as the period of the common-mode signal is greater than the one-shot period.
1 DIN GND1 18
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Figure 1. Block Diagram Waveforms
ISOLATION BARRIER 7 8 9 LTC1145 NC OSCIN GND2 VCC OS DOUT
LTC1145/6 * F02
5V 12 11 10 TTL OUT
Figure 2. Common-Mode Rejection Test Circuit
7
LTC1145/LTC1146
OPERATIO
Internal Capacitors A special lead frame has been designed for the LTC1145/ LTC1146 which includes two die paddles and the isolation capacitors. Each capacitor is formed by three parallel metal fingers spaced about 20 mils apart. The capacitors' metal fingers and bonding posts replace the 5 center pins on each side of the 18-pin package. The dielectric for the capacitors is the plastic package moulding compound. The material has a high dielectric constant and a high breakdown voltage. Typically the capacitance between the input and output is in the order of 1pF. This provides sufficient isolation in even the most critical of applications and is suitable for handling high voltage with high V/t.
TYPICAL APPLICATIO S
Isolated RS232 Driver/Receiver
VIN = 5V 10% FROM SYSTEM 47 CTX20-1 1:1 1N5818 1 IN
+
100F
ILIM
VIN SW1
LT1111 FB GND SW2
12 ISOLATOR OUTPUT (DATA TO SYSTEM) VOUT 11 VCC OS DIN LTC1145 9 18 1 1 0.1F 3 4 0.1F 5 LT1181A RS232
GND2
GND1
ISOLATOR INPUT (DATA FROM SYSTEM)
VIN
1
VCC DIN LTC1145 OS
18
GND1
GND2
SYSTEM GROUND
ISOLATION BARRIER
8
U
U
L1 20H 1N5818 13.7V 10k
+
100F 0.1F
LT1121-5 OUT GND
5V 10%
+
10F
+
1F
1k
16 VCC
2 0.1F
6 0.1F
12 9 11 11 9 DX RX 8 RS232 INPUT
14 15
LTC1145/6 * TA03
RS232 OUTPUT
FLOATING GROUND
LTC1145/LTC1146
TYPICAL APPLICATIO S
300V Isolated High-Side Driver
VCC = 13V* ISOLATION BARRIER 1 5V 0V 200kHz DIN LTC1145 GND1 18 12 VCC OS GND2 9 OUTPUT *VCC IS AN OUTPUT-REFERENCED SUPPLY MUR1560 RLOAD
LTC1145/6 * TA04
Isolated Battery Power Temperature-to-Frequency Converter
0.02F TYPE K THERMOCOUPLE 6V +V LT1025 GND R- 100C TRIM 6.81k* 1.5k C3 0.47F 100k 6V 10k 1M Q2 2N3906 C1 100pF 240k 6V 6.8F LT1004-1.2 NC Q1 2N3904 I1 I2
-+
"A"
*IRC/TRW-MTR-5, +120PPM = 74C14 15
= POLYSTYRENE
FOR GENERAL PURPOSE 4mV FULL SCALE VF DELETE THERMOCOUPLE/LT1025 PAIR AND DRIVE POINT "A"
U
MUR450 1.5k
V + = 300V
1N752A 11
+ 100F
25V
0.1F CER
+
1F TL4426 IRF840
+
180F 400V
+
-
A1 LTC1049 CONTROL AMPLIFIER 16 14 S1 S3 2 1 3
VF 100k I3 OUTPUT 0C TO 100C = 0kHz TO 1kHz
C4 300pF 1 12
+
DIN VCC 10 DOUT 18 LTC1146 9 GND1 GND2
9 C2 390pF 11 S4 S2 6 8 7
LTC1145/6 * TA05
10 LTC201 CHARGE PUMP
9
LTC1145/LTC1146
TYPICAL APPLICATIO S
Isolated 10-Bit Data Acquisition Systems
FERRITE BEAD OUT IN LT1121-5 47F GND
+
7.45V
74C14 24pF
10k
+
1F
VIN LT1021-5 GND OUT 5V
8-CHANNEL ANALOG INPUTS
LTC1090 ACLK SCLK DIN DOUT CS 5VREF
VCC
10F
SYSTEM GROUND 18 FLOATING GROUND
10
U
5V
1N5818
+
10F
CTX20-1 1:1 * 20H * 47
+
47F
5V INPUT FROM SYSTEM
1N5818 10k 10F 1k
VIN ILIM SW1 LT1111 FB GND SW2
+
+
1F 11
12 VCC OS LTC1145 GND2 9 GND1 DIN
1 SCK 18
11
12 VCC OS LTC1145 GND2 9
DIN GND1
1 MOSI 18 TO 68HC05
12 11 VCC OS LTC1145 GND2 0.01F CER 9 GND1 18 DIN 1 CO
+
1
12 DIN GND1 VCC LTC1145 OS GND2
LTC1145/6 * TA06
11 MISO 9
ISOLATION BARRIER
LTC1145/LTC1146
TYPICAL APPLICATIO S
AC Line Monitor
FUSE 110 VAC 1.35F 400V 161k AC 60Hz V150LA20 (GE) TRANSIENT ABSORBER V+ ZENER 2W 18V
18
3k GND1 DIN 1 15k 14 OUT V+ AD537 IN 5 1 8.3k 13 12 1nF 11 10 20k 9 GND2 9 8 3 4 100k 100k 1N5712
ISOLATION BARRIER LTC1145 LINE VOLTAGE FREQUENCY OUT FS = 100kHz 11 OSOUT VCC
10V
100k
18
3k GND1 DIN 1 15k 14 OUT V+ 1 8.3k 13 12 1nF 11 10 20k 9 GND2 9 8 SYSTEM GROUND FLOATING GROUND 3 4 100k 1k 1N5712
ISOLATION BARRIER LTC1145 LOAD CURRENT FREQUENCY OUT FS = 100kHz 11 OSOUT VCC
10V
1k
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of circuits as described herein will not infringe on existing patent rights.
+
+
5V 12
LT1013
1N5712
LT1013
LTC1145/6 * TA07
-
AD537 5 IN
+
-
+
5V 12
LT1013
1N5712
LT1013
-
-
+
U
ILOAD(MAX) = 0.1V/RSHUNT
1N5819
1N5819 V-
LOAD
+
100F 25V
ZENER 2W 18V
47F 50V
10k RSHUNT
20pF
1.02k
11
LTC1145/LTC1146
PACKAGE DESCRIPTIO
0.300 - 0.325 (7.620 - 8.255)
0.009 - 0.015 (0.229 - 0.381)
0.015 (0.381) MIN
(
+0.025 0.325 -0.015 +0.635 8.255 -0.381
)
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
U
Dimensions in inches (millimeters) unless otherwise noted.
N Package 18-Lead Plastic DIP
0.905 (22.860) MAX 18 12 11 10
0.260 0.010 (6.604 0.254)
1 0.130 0.005 (3.302 0.127) 0.045 - 0.065 (1.143 - 1.651)
7
8
9
0.065 (1.651) TYP 0.045 0.015 (1.143 0.381) 0.100 0.010 (2.540 0.254) 0.018 0.003 (0.457 0.076)
0.125 (3.175) MIN
N18 0893
LT/GP 0394 10K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1994

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