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LT1328 4Mbps IrDA Infrared Receiver
FEATURES
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DESCRIPTION
The LT (R)1328 is a photodiode receiver that supports IrDA(R) data rates up to 4Mbps as well as other modulation methods such as Sharp ASK and TV remote control. The LT1328 MSOP contains all the necessary circuitry to convert current pulses from an external photodiode to a digital TTL output while rejecting unwanted lower frequency interference. The LT1328 plus five external components is all that is required to make an IrDA compatible receiver. Power requirements for the LT1328 are minimal--a single 5V supply and 2mA of quiescent current. Internal highpass filtering attenuates interfering signals such as sunlight, incandescent and fluorescent lamps and is selectable at Pin 7 for low or high data rates. The LT1328's ease of use and flexibility make it an ideal solution for numerous other photodiode receiver applications. The LT1328 is available in the SO-8 as well as the tiny MSOP for size-critical applications.
, LTC and LT are registered trademarks of Linear Technology Corporation. IrDA is a registered trademark of the Infrared Data Association.
SIR, FIR and 4ppm Compatible Low Frequency Ambient Rejection Loop Supply Current: 2mA 8-Lead MSOP and SO Packages 5V Single Supply Operation Optional High Frequency Noise Rejection
APPLICATIONS
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IrDA Applications Sharp/Newton TV Remote Noncontact Telemetry Wireless Slave for Photographic Flash Keyless Entry Optical Data Transfer Infrared Home Control Systems
TYPICAL APPLICATIONS N
IrDA Receiver
C6 1000pF 8 HIGH: SIR LOW: FIR AND 4ppm (OPTIONAL) OPTIONAL SHUTDOWN CIRCUIT 5V C2 4.7F ENABLE *SILICONIX
1328 TA01
LT1328 1 LIGHT IN TEMIC BPV22NF D1 C1 10nF C4 330pF 2 IN VBIAS
7 FILTER MODE 3 FILTER 6 VCC SWITCH 4 5 DATA GND TTL DATA OUT
TP0610L* 5V
TRANSMIT INPUT
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IrDA Transmitter
VCC C5 4.7F D2 HSDL-4220* R3 3.9 1/2W Q3 2N7002
R1 100 R2 10k
*HEWLETT PACKARD
1328 TA02
1
LT1328
ABSOLUTE MAXIMUM RATINGS
Total Supply Voltage (VCC to GND) ........................... 6V Differential Voltage (Any Two Pins) .......................... 6V Operating Temperature Range .................... 0C to 70C Specified Temperature Range ..................... 0C to 70C Maximum Junction Temperature ......................... 150C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW IN FILTER FILTER SWITCH GND 1 2 3 4 8 7 6 5 VBIAS MODE VCC DATA
IN 1 TOP VIEW 8 VBIAS 7 MODE 6 VCC 5 DATA
LT1328CMS8 MS8 PART MARKING LTBG
MS8 PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 150C, JA = 250C/ W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER ITH(MIN) Minimum Input Current Pulse CONDITIONS
VCC = 5V, VGND = 0V, VMODE = 2V unless otherwise specified. (Note 1)
MIN TYP 200 600
q
Current Out of Pin 1 (SIR), Pulse Width 1.6s, Period 8.7s Current Out of Pin 1 (FIR, 4ppm), Pulse Width 125ns, Period 500ns Current Out of Pin 1 DC to 120Hz, Current Out of Pin 1 No Input Signal No Input Signal No Input Signal No Input Signal
q q q q q q q
IPD IREJECT IS VS VIN VBIAS VLT VTHL VTHH VOL VOH
Maximum Input Current Maximum Low Frequency Input Current Supply Current Operating Supply Voltage Bias Voltage on Pin 1 Bias Voltage on Pin 8 Quiescent Voltage on Pin 2 Switch Logic Level Low Pin 7 Switch Logic Level High Pin 7 Comparator Output Low Comparator Output High
Voltage On Pin 5, 800A Sink Current Voltage On Pin 5, 50A Source Current
The q denotes specifications which apply over the full operating temperature range of 0C TA 70C.
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ORDER PART NUMBER LT1328CS8 S8 PART MARKING 1328
FILTER 2 FILTER 3 SWITCH GND 4
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 150C, JA = 190C/ W
MAX
UNITS nA nA mA A
15
30 1000 2 3 5.5 1.5 1.5 1.5 2.0 2.0 2.0 0.8
mA V V V V V V V V
4.5 1.0 1.0 1.0 2.0 0.4 4.0 4.3
q q
0.5
Note 1: MS8 package devices are designed for and intended to meet commercial temperature range specifications but are not tested at 0C.
LT1328 TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Supply Voltage
4 4
CHANGE IN VOLTAGE ON PIN 1 (mV)
SUPPLY CURRENT (mA)
3
OUTPUT PULSE WIDTH 100 (%) INPUT PULSE WIDTH
IPIN1 = 0nA VPIN7 = 0V TA = 25C
2
1
0
0
1
2
345678 SUPPLY VOLTAGE (V)
Change in Output Pulse Width vs Input Duty Cycle
250 10
200
CHANGE IN VOLTAGE ON PIN 1 (mV)
OUTPUT PULSE WIDTH 100 (%) INPUT PULSE WIDTH
VS = 5V VFILT = 10nF VBIAS = 1000pF PULSE PERIOD = 8.7s
150 IPIN1 = 150nA TO 3mA 100 IPIN1 > 3mA TO 10mA 50
0
1
Change in Voltage on Pin 2 vs Current
2.0 1000
1.5
PEAK INPUT CURRENT AMPLITUDE (A)
CHANGE IN VOLTAGE ON PIN 2 (V)
VS = 5V TA = 25C
1.0 SOURCING CURRENT 0.5
0 SINKING CURRENT - 0.5 0.1 1 10 100 1000 10000 100000 CURRENT (PIN 1) (A)
1328 G06
UW
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1328 G01
Change in Voltage on Pin 1 vs Supply Voltage
200 IPIN1 = 0nA TA = 25C 2
Change in Output Pulse Width vs Input Current Amplitude
VS = 5V VFILT = 10nF VBIAS = 1000pF FOR INPUT PULSE WIDTHS OF 8.6s TO 0.22s PULSE PERIOD = 8.7s
150
0
100
-2
50
10
-4
0
1
2
345678 SUPPLY VOLTAGE (V)
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10
0 0.1
1
100 1000 10 INPUT CURRENT (A)
10000
1328 G03
1328 G02
Change in Voltage on Pin 1 vs Current
CURRENT SINKING FROM PIN 1 0 VS = 5V TA = 25C
-10 CURRENT SOURCING FROM PIN 1 -20
-30
- 40 3 30 10 INPUT DUTY CYCLE (%) 100
1328 G04
0.1
1
10 100 1000 10000 100000 CURRENT (PIN 1) (A)
1328 G05
Peak Interfering Current vs Frequency
VS = 5V CBIAS = 1000pF CURRENT IS SOURCED OUT OF PIN 1 CFILT = 330pF CFILT = 10nF 1 AREA OF SIGNAL REJECTION
100
10
0.1 0.01
0.1
10 1 FREQUENCY (kHz)
100
1000
1328 G07
3
LT1328
PIN FUNCTIONS
IN (Pin 1): Connect this pin to the photodiode cathode. This is the input to the preamplifier and is held at 1.5V by the output of the DC servo. To maintain the 1.5V on this pin, the DC servo can source up to 2mA or sink 40A to this pin. FILTER (Pin 2): Connect a capacitor from this pin to ground. The value of the capacitor will set the band of frequencies that will be attenuated by the servo. The pole is set by the formula f = 25/(2 * 60k * C). A 330pF capacitor will attenuate photodiode signals below 200kHz when operating at high data rates (FIR and 4ppm). FILTER SWITCH (Pin 3): Collector of a Transistor Switch. When the MODE switch (Pin 7) is TTL HIGH this pin will be switched to ground. This pin is used to increase the filter capacitor for slower data rates (SIR). A 10nF capacitor from Pin 2 to Pin 3 will bring the highpass frequency down to 6.6kHz for SIR. GND (Pin 4): Ground. DATA (Pin 5): TTL Output of the Comparator. A TTL LOW at this pin indicates that the photodiode has received a pulse of light. This pin will remain HIGH when the light signal and noise are below the attenuation band of the DC servo. VCC (Pin 6): 5V Supply. A bypass capacitor, connected as close as possible from Pin 6 to ground is recommended (4.7F). MODE (Pin 7): A TTL HIGH on this pin will cause the open collector at Pin 3 to switch to ground. This is an option that switches in extra capacitance for lower frequency data rates. If this pin is not used, select a capacitor (C4) to accommodate the lowest data rate (for IrDA C4 = 10nF). VBIAS (Pin 8): A 1000pF capacitor from this pin to ground is required.
BLOCK DIAGRAM
D1 PHOTODIODE TEMIC BPV22NF
C4 330pF
C1 10nF 3
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VCC
RFB 50k
1.5V
VBIAS
8 C6 1000pF
1
IN RIN 2k
PREAMP
BIAS
MODE FILTER DC SERVO
7
HIGH: SIR LOW: FIR AND 4ppm
+
2 FILTER FILTER SWITCH gm 60k 5V
-
VCC
6 C2 4.7F
4
GND
-
COMPARATOR
DATA
5
+
1328 BD
Figure 1. LT1328 Block Diagram
LT1328
APPLICATIONS INFORMATION
The LT1328 is a low noise, high speed, high gain infrared receiver designed to easily provide IR communications with portable computers, PDAs, desktop computers and peripherals. The receiver takes the photodiode current from an infrared photodiode (typically Temic BPV22NF) and performs a current-to-voltage conversion. Figure 1 is a block diagram of the LT1328. Photodiode current is transformed into a voltage by feedback resistor RFB. The DC level of the preamp is held at VBIAS due to the servo action of the transconductance amplifier gm. The servo action only suppresses frequencies below the Rgm, CFILT pole. This highpass filtering attenuates interfering signals such as sunlight, incandescent and fluorescent lamps. For higher data rates, the rejection band can be increased to include higher frequencies (Pin 7 LOW). If this option is not used, Pin 7 is grounded and Pin 3 is open. The rejection band of the filter is then determined by the lowest data rate; C4 equals 10nF for IrDA (SIR, FIR and 4ppm). The highpass filter break point is set by the capacitor from Pin 2 to ground at f(Hz) = 25/(2 * Rgm * C) where Rgm = 60k. The 330pF capacitor in Figure 1 sets a 200kHz corner frequency and is used for data rates above 115kbps. For low data rates (115kbps and below) Pin 7 should be set to TTL HIGH which grounds Pin 3 and reduces the break frequency with the addition of the capacitor between Pins 2 and 3. A 10nF capacitor produces a 6.6kHz corner. Signals passed by the preamp/gm amplifier combination cause the comparator output to swing low. Performance of the LT1328 circuit in Figure 1 extends over the full 1cm to 1 meter range of the IrDA standard at the stipulated light levels. For IrDA data rates of 115kbps and below, a 1.6s pulse width is used for a logic zero and no pulse for a logic one. Light levels are 40mW/SR to 500mW/SR. Figure 2 shows a scope photo for a transmitter input (bottom trace) and the LT1328 output (top trace). Note that the input to the transmitter is inverted, i.e., a high at the input is light transmitted, which is a zero at the output of the transmitter (Pin 5). The MODE pin (Pin 7) should be high for these data rates. The second fastest tier of the IrDA standard addresses 576kbps and 1.152Mbps data rates with pulse widths of 1/4 of the bit interval for zero and no pulse for one. The
0
1
0
DATA RATES: 2400BAUD TO 115kbps BIT INTERVAL: 417s TO 8.7s PULSE WIDTH: 3/16 OF INTERVAL OR 1.63s
IrDA-SIR (1m)
RECEIVER OUTPUT
TRANSMITTER INPUT
Figure 2. IrDA-SIR Modulation
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NRZ DATA 0 1 1 0 1 0 IrDA-SIR HIGH = LIGHT TRANSMITTED
1328 F02a
IrDA-SIR (1cm)
RECEIVER OUTPUT
TRANSMITTER INPUT
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LT1328
APPLICATIONS INFORMATION
1.152Mbps rate, for example, uses pulses of 217ns for its bit time of 870ns. Light levels are 100mW/SR to 500mW/ SR over the 1cm to 1 meter range. A photo of a transmitted input and LT1328 output is shown in Figure 3. The LT1328 output pulse width will be less than 800ns wide over all of the above conditions at 1.152Mbps. Pin 7 should be held low for these data rates and above. The last IrDA encoding method is for 4Mbps and uses pulse position modulation, thus its name 4ppm. Two bits are encoded by the location of a 125ns wide pulse at one of the four positions within a 500ns interval (2 bits * 1/500ns = 4Mbps). Range and input levels are the same as for 1.152Mbps. Figure 4 shows the LT1328 reproduction of this modulation.
NRZ DATA 0 1 0 0 1 1 0 1 0 IrDA-FIR HIGH = LIGHT TRANSMITTED DATA RATES: FIXED AT 1.15Mbps BIT INTERVAL: 870ns PULSE WIDTH: 1/4 OF INTERVAL OR 217ns
1328 F03a
IrDA-FIR (1m)
RECEIVER OUTPUT
TRANSMITTER INPUT
Figure 3. IrDA-FIR Modulation
DATA BIT PAIR 00 01 10 11 4ppm DATA SYMBOL 1000 0100 0010 0001 NRZ DATA 0 1 0 0 1 1 0 1 0 IrDA 4ppm HIGH = LIGHT TRANSMITTED DATA RATES: FIXED AT 4Mbps BIT INTERVAL: 500ns PULSE WIDTH: 1/4 OF INTERVAL OR 125ns
1328 F04a
IrDA-4ppm(1m)
RECEIVER OUTPUT
TRANSMITTER INPUT
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IrDA-FIR (1cm)
RECEIVER OUTPUT
TRANSMITTER INPUT
IrDA-4ppm (1cm)
RECEIVER OUTPUT
TRANSMITTER INPUT
Figure 4. IrDA-4ppm
LT1328
APPLICATIONS INFORMATION
In situations where long range is not a requirement, a very simple IR link can be made using unmodulated NRZ (nonreturn to zero) data. The circuit is shown in Figure 5. A BER (bit-error rate) transmitter and receiver was used to test the data-link error rates for data rates of 375kbps. Because the NRZ data can have long stretches of continuous "1" data, the low frequency corner of the LT1328 photodiode receiver is set to 14Hz to prevent pulse-top distortion.
5V C5 4.7F R1 100 R2 10k D2 HSDL 4220 R3 3.9 1/2W Q3 2N7002 24"
BIT ERROR RATE TRANSMITTER/RECEIVER 375bps NRZ DATA OUT IN
1328 F05
Figure 5. Simple NRZ Data Link
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To do this, make C1 4.7F. This is the only change from a standard IrDA-SIR receiver. A range of 24" (with a bit error rate lower than 1 in 108) is achieved with no additional processing beyond that provided by the LT1328. A caution: when using unmodulated data, it is possible to get a 100% duty cycle on the LED transmitter, so be sure that the LED can handle this.
1 D1 TEMIC BPV22NF NC C4 4.7F 2 3 4 LT1328
8 7 6 5 C2 4.7F C6 1000pF 5V
7
LT1328
APPLICATIONS INFORMATION
There is one drawback to the previous scheme. Lowering the highpass frequency to 14Hz negates the normally excellent ambient light rejection of the LT1328 to lineoperated light sources. By modulating the data in a very simple and inexpensive way the ambient light rejection can be maintained. The NRZ data is used to gate a 3MHz square wave before driving the transmitter. The LT1328 in FIR-4ppm mode (bandwidth of 1MHz to 4MHz) will receive the 3MHz signal. Thus, the low frequency response is no longer required and the LT1328 can be configured as
5V D2 HSDL 4220 R3 3.9 1/2W Q3 2N7002 C8 100pF BIT ERROR RATE TRANSMITTER/RECEIVER 74LS00 3 2 1 375bps NRZ DATA OUT IN 5 6 7 11 1/2 74LS123 10 9 3MHz 13 1/2 74LS123 R5 46.4k 1% 5V R4 5k 1% 15 C7 10pF 14 1 2 3
1328 F06
> 30"
C5 4.7F
R1 100 R2 10k
Figure 6. Simple Data Link with Improved Low Frequency Noise Rejection
TYPICAL APPLICATIONS N
Wireless Slave for Photographic Flash
R1 100 LIGHT FROM MASTER FLASH D1 HAMAMATSU S4797-01 C4 330pF NC
1 2 3 4 LT1328
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a FIR receiver with no changes. Note that when in FIR/ 4ppm mode, the LT1328 has excellent rejection to activeballast fluorescent lights (40kHz to 100kHz) as well as line operated bulbs. The data is recovered with two stages of retriggerable one-shots on the output of the LT1328. The first one-shot pulse length is set to 80ns and acts as an edge detector and the second one-shot pulse length is set to 2.3s, just under a symbol period. With this modulation, the range can be extended to over 30" and still have a bit error rate lower than 1 in 108.
1 D1 TEMIC BPV22NF NC C4 100pF 2 3 4 LT1328
8 7 6 5 C2 4.7F C6 1000pF 5V
8 7 6 5
NC 5V NC R2 1k D2 1N4148 R4 10k R3 10k
TO HOT SHOE OF SLAVE FLASH
Q1 MPS2907A
C2 4.7F Q2 MPSA42
R5 1k
C5 0.1F
D3 MUR 160524
1328 TA05
Noncontact Voltmeter
TYPICAL APPLICATIONS N
R1 1M
SET INPUT VOLTAGE TO 200V, ATTACH FREQUENCY COUNTER TO PIN 8 OF LTC1440 AND ADJUST R1 FOR 200Hz 7 LTC1440 C9 10F R9 16 D2 HSDL-4220 RANGE: 6 FT 14 6 D1 TEMIC BPV22NF NC 5 4 C4 330pF
R2 6.2M
C3 1F
+
D3 1N4148
3
+
8
1 2 3 4 LT1328
8 7 6 5 C6 1000pF
C5 1F FILM
4
-
C8 0.01F R8 2k 7 1 2 3
C7 220pF
5
+
5V C2 4.7F C10 10nF 15
R3 16
R4 51k
6
R5 1M 2 10 9 8 1
R10 20k 5V 5V 14 1
R6 75k
Q2 VN2222
Q1 VN2222 13 12 11 NC 74HC86
2 3
ALL RESISTORS 1%, 1/4W UNLESS OTHERWISE NOTED
1/2 LS221
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FREQUENCY COUNTER 1Hz = 1V
1328 TA06
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VIN 20V TO 400V
R7 50k 5W D4 5.6V
LT1328
9
LT1328
PACKAGE DESCRIPTION
0.007 (0.18) 0.021 0.004 (0.53 0.01)
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
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Dimensions in inches (millimeters) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 0.004* (3.00 0.10) 8 76 5
0.192 0.004 (4.88 0.10)
0.118 0.004** (3.00 0.10)
1
23
4
0.040 0.006 (1.02 0.15) 0 - 6 TYP SEATING PLANE
0.006 0.004 (0.15 0.10)
0.012 (0.30)
0.025 (0.65) TYP
MSOP08 0596
LT1328
PACKAGE DESCRIPTION U
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 7 6 5
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
2
3
4
0.053 - 0.069 (1.346 - 1.752)
0.004 - 0.010 (0.101 - 0.254)
0.016 - 0.050 0.406 - 1.270 *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
SO8 0996
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 its circuits as described herein will not infringe on existing patent rights.
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LT1328
TYPICAL APPLICATIONS N
IrDA Receiver
LT1328 1 D1 BPV22NF* C1 10nF *TEMIC E1 GND
1328 TA03
IN
SHDN
2
FILTER MODE 3 FILTER 6 VCC SWITCH 4 5 DATA GND C2 4.7F
C4 330pF
RELATED PARTS
PART NUMBER
LT1016 LT1116 LT1319 LT1361
DESCRIPTION
UltraFastTM Precision Comparator Single Supply, Ground Sensing Comparator Multiple Modulation Standard Infrared Receiver Dual 4mA, 50MHz, 800V/s Op Amp
UltraFast and C-Load are trademarks of Linear Technology Corporation.
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417 q (408) 432-1900 FAX: (408) 434-0507q TELEX: 499-3977 q www.linear-tech.com
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IrDA Transmitter
C6 1000pF JP1 123 VCC E2 MODE E3 VCC E4 DATA
VCC C5 4.7F R1 100 5% E6 TRANS R2 10k 5% *HEWLETT PACKARD D2 HSDL-4220* R3 3.9 1/2W Q1 2N7002
E5 GND
1328 TA04
COMMENTS
10ns Prop Delay 12ns Prop Delay Supports IrDA, SIR and FIR, Sharp/Newton and TV Remote C-LoadTM Op Amp Stable with All Capacitive Loads
1328f LT/TP 0597 7K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1997

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