LT1328CS8#TRPBF [Linear]
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| 型号： | LT1328CS8#TRPBF |
| 厂家： | 
Linear |
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LT1328
4Mbps IrDA
Infrared Receiver
U
FEATURES
DESCRIPTION
The LT®1328 is a photodiode receiver that supports IrDA®
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 fre-
quency interference. The LT1328 plus five external com-
ponents is all that is required to make an IrDA compatible
receiver.
■
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
U
APPLICATIONS
■
IrDA Applications
PowerrequirementsfortheLT1328areminimal—asingle
5V supply and 2mA of quiescent current. Internal high-
passfilteringattenuatesinterferingsignalssuchassunlight,
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.
■
Sharp/Newton
■
TV Remote
Noncontact Telemetry
Wireless Slave for Photographic Flash
Keyless Entry
Optical Data Transfer
Infrared Home Control Systems
■
■
■
■
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
IrDA is a registered trademark of the Infrared Data Association.
U
TYPICAL APPLICATIONS N
IrDA Receiver
IrDA Transmitter
HIGH: SIR
LOW: FIR AND 4ppm
(OPTIONAL)
V
CC
C6
1000pF
LT1328
C5
4.7µF
OPTIONAL
SHUTDOWN
CIRCUIT
D2
1
2
3
4
8
7
6
5
IN
V
HSDL-4220*
LIGHT IN
TEMIC
BPV22NF
BIAS
D1
R3
3.9Ω
1/2W
FILTER MODE
FILTER
C1
TP0610L*
5V
R1
5V
10nF
V
CC
100Ω
SWITCH
TRANSMIT
INPUT
Q3
C2
4.7µF
C4
330pF
2N7002
GND
DATA
R2
10k
ENABLE
TTL
DATA OUT
*SILICONIX
1328 TA02
*HEWLETT PACKARD
1328 TA01
1
LT1328
W W U W
ABSOLUTE MAXIMUM RATINGS
Total Supply Voltage (VCC to GND) ........................... 6V
Differential Voltage (Any Two Pins) .......................... 6V
Operating Temperature Range .................... 0°C to 70°C
Specified Temperature Range..................... 0°C to 70°C
Maximum Junction Temperature ......................... 150°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
U
W U
PACKAGE/ORDER INFORMATION
ORDER PART
ORDER PART
TOP VIEW
NUMBER
NUMBER
TOP VIEW
1
2
3
4
8
7
6
5
IN
V
BIAS
IN
FILTER
FILTER SWITCH
GND
1
2
3
4
8 V
BIAS
LT1328CS8
LT1328CMS8
FILTER
FILTER
SWITCH
MODE
7 MODE
6 V
CC
V
CC
5 DATA
GND
DATA
MS8 PACKAGE
8-LEAD PLASTIC MSOP
TJMAX = 150°C, θJA = 250°C/ W
MS8 PART MARKING
LTBG
S8 PART MARKING
1328
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 190°C/ W
Consult factory for Industrial and Military grade parts.
VCC = 5V, VGND = 0V, VMODE = 2V unless otherwise specified. (Note 1)
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Minimum Input Current Pulse
Current Out of Pin 1 (SIR), Pulse Width 1.6µs,
Period 8.7µs
200
nA
TH(MIN)
Current Out of Pin 1 (FIR, 4ppm), Pulse Width 125ns,
Period 500ns
600
nA
I
I
Maximum Input Current
Current Out of Pin 1
●
15
30
mA
PD
Maximum Low Frequency
Input Current
DC to 120Hz, Current Out of Pin 1
1000
µA
REJECT
I
Supply Current
No Input Signal
●
●
●
●
●
●
●
●
●
2
3
mA
V
S
V
Operating Supply Voltage
Bias Voltage on Pin 1
4.5
1.0
1.0
1.0
5.5
2.0
2.0
2.0
0.8
S
V
V
V
V
V
V
V
No Input Signal
No Input Signal
No Input Signal
1.5
1.5
1.5
V
IN
Bias Voltage on Pin 8
V
BIAS
LT
Quiescent Voltage on Pin 2
Switch Logic Level Low Pin 7
Switch Logic Level High Pin 7
Comparator Output Low
Comparator Output High
V
V
THL
THH
OL
2.0
4.0
V
Voltage On Pin 5, 800µA Sink Current
Voltage On Pin 5, 50µA Source Current
0.4
4.3
0.5
V
V
OH
The
● denotes specifications which apply over the full operating tempera-
Note 1: MS8 package devices are designed for and intended to meet
commercial temperature range specifications but are not tested at 0°C.
ture range of 0°C ≤ T ≤ 70°C.
A
2
LT1328
W
U
TYPICAL PERFORMANCE CHARACTERISTICS
Change in Voltage on Pin 1
vs Supply Voltage
Change in Output Pulse Width
vs Input Current Amplitude
Supply Current vs Supply Voltage
4
3
2
1
0
200
150
100
50
4
2
I
V
T
= 0nA
= 0V
I
= 0nA
V
V
V
= 5V
PIN1
PIN1
A
S
T
= 25°C
= 10nF
PIN7
FILT
BIAS
= 25°C
= 1000pF
A
FOR INPUT PULSE WIDTHS
OF 8.6µs TO 0.22µs
PULSE PERIOD = 8.7µs
0
–2
–4
0
0
1
2
3
4
5
6
7
8
9
10
0.1
1
10
100
1000 10000
0
1
2
3
4
5
6
7
8
9
10
SUPPLY VOLTAGE (V)
INPUT CURRENT (µA)
SUPPLY VOLTAGE (V)
1328 G01
1328 G03
1328 G02
Change in Output Pulse Width
vs Input Duty Cycle
Change in Voltage on Pin 1
vs Current
250
200
150
100
50
10
0
V
V
V
= 5V
CURRENT SINKING
FROM PIN 1
V
A
= 5V
S
S
= 10nF
T
= 25°C
FILT
BIAS
= 1000pF
PULSE PERIOD = 8.7µs
–10
–20
CURRENT SOURCING
FROM PIN 1
I
= 150nA TO 3mA
> 3mA TO 10mA
PIN1
I
PIN1
–30
–40
0
0.1
10
100 1000 10000 100000
1
3
10
30
100
1
CURRENT (PIN 1) (µA)
INPUT DUTY CYCLE (%)
1328 G05
1328 G04
Change in Voltage on Pin 2
vs Current
Peak Interfering Current
vs Frequency
2.0
1.5
1.0
0.5
1000
100
10
V
C
= 5V
S
BIAS
V
= 5V
= 25°C
S
A
= 1000pF
T
CURRENT IS
SOURCED
OUT OF PIN 1
C
= 330pF
FILT
SOURCING
CURRENT
C
= 10nF
FILT
AREA OF
SIGNAL
REJECTION
1
0
SINKING
CURRENT
–0.5
0.1
0.1
10
100 1000 10000 100000
1
0.01
0.1
1
10
100
1000
CURRENT (PIN 1) (µA)
FREQUENCY (kHz)
1328 G06
1328 G07
3
LT1328
U
U
U
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,theDCservocansourceupto2mAorsink40µAtothis
pin.
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.
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/(2π • 60k • C). A 330pF
capacitor will attenuate photodiode signals below 200kHz
when operating at high data rates (FIR and 4ppm).
V
CC (Pin 6): 5V Supply. A bypass capacitor, connected as
close as possible from Pin 6 to ground is recommended
(4.7µF).
MODE (Pin 7): A TTL HIGH on this pin will cause the open
collectoratPin3toswitchtoground. Thisisanoptionthat
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).
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.
V
BIAS (Pin 8): A 1000pF capacitor from this pin to ground
is required.
W
BLOCK DIAGRAM
V
CC
R
FB
50k
V
8
1.5V
BIAS
C6
1000pF
1
IN
PREAMP
BIAS
D1
R
IN
PHOTODIODE
TEMIC
2k
BPV22NF
MODE
7
6
HIGH: SIR
LOW: FIR AND 4ppm
FILTER
DC SERVO
+
2
3
FILTER
g
m
60k
5V
C4
330pF
C1
10nF
V
CC
–
FILTER SWITCH
GND
C2
4.7µF
4
–
DATA
5
COMPARATOR
+
1328 BD
Figure 1. LT1328 Block Diagram
4
LT1328
U
W U U
APPLICATIONS INFORMATION
The LT1328 is a low noise, high speed, high gain infrared
receiverdesignedtoeasilyprovideIRcommunicationswith
portablecomputers,PDAs,desktopcomputersandperiph-
erals. The receiver takes the photodiode current from an
infrared photodiode (typically Temic BPV22NF) and per-
forms a current-to-voltage conversion. Figure 1 is a block
diagramoftheLT1328.Photodiodecurrentistransformed
intoavoltagebyfeedbackresistorRFB. TheDClevelofthe
preamp is held at VBIAS due to the servo action of the
transconductanceamplifiergm.Theservoactiononlysup-
presses frequencies below the Rgm, CFILT pole.
datarates(115kbpsandbelow)Pin7shouldbesettoTTL
HIGH which grounds Pin 3 and reduces the break fre-
quency 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
andbelow,a1.6µspulsewidthisusedforalogiczeroand
no pulse for a logic one. Light levels are 40mW/SR to
500mW/SR.
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
notused,Pin7isgroundedandPin3isopen.Therejection
bandofthefilteristhendeterminedbythelowestdatarate;
C4 equals 10nF for IrDA (SIR, FIR and 4ppm). The high-
pass filter break point is set by the capacitor from Pin 2 to
ground at f(Hz) = 25/(2π • Rgm • C) where Rgm = 60k. The
330pF capacitor in Figure 1 sets a 200kHz corner fre-
quencyandisusedfordataratesabove115kbps. Forlow
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
NRZ DATA
0
1
0
0
1
1
0
1
0
IrDA-SIR HIGH = LIGHT TRANSMITTED
1328 F02a
DATA RATES: 2400BAUD TO 115kbps
BIT INTERVAL: 417µs TO 8.7µs
PULSE WIDTH: 3/16 OF INTERVAL OR 1.63µs
IrDA-SIR (1m)
IrDA-SIR (1cm)
RECEIVER
OUTPUT
RECEIVER
OUTPUT
TRANSMITTER
INPUT
TRANSMITTER
INPUT
Figure 2. IrDA-SIR Modulation
5
LT1328
U
W U U
APPLICATIONS INFORMATION
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). Rangeandinputlevelsarethesameas
for 1.152Mbps. Figure 4 shows the LT1328 reproduction
of this modulation.
1.152Mbpsrate,forexample,usespulsesof217nsforits
bittimeof870ns. Lightlevelsare100mW/SRto500mW/
SR over the 1cm to 1 meter range. A photo of a transmit-
ted 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.
NRZ DATA
0
1
0
0
1
1
0
1
0
IrDA-FIR HIGH = LIGHT TRANSMITTED
1328 F03a
DATA RATES: FIXED AT 1.15Mbps
BIT INTERVAL: 870ns
PULSE WIDTH: 1/4 OF INTERVAL OR 217ns
IrDA-FIR (1m)
IrDA-FIR (1cm)
RECEIVER
OUTPUT
RECEIVER
OUTPUT
TRANSMITTER
INPUT
TRANSMITTER
INPUT
Figure 3. IrDA-FIR Modulation
DATA BIT 4ppm DATA
NRZ DATA
PAIR
SYMBOL
0
1
0
0
1
1
0
1
0
00
01
10
11
1000
0100
0010
0001
IrDA 4ppm HIGH = LIGHT TRANSMITTED
1328 F04a
DATA RATES: FIXED AT 4Mbps
BIT INTERVAL: 500ns
PULSE WIDTH: 1/4 OF INTERVAL OR 125ns
IrDA-4ppm(1m)
IrDA-4ppm (1cm)
RECEIVER
OUTPUT
RECEIVER
OUTPUT
TRANSMITTER
INPUT
TRANSMITTER
INPUT
Figure 4. IrDA-4ppm
6
LT1328
U
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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.
ABER(bit-errorrate)transmitterandreceiverwasusedto
test the data-link error rates for data rates of 375kbps.
Because the NRZ data can have long stretches of continu-
ous “1” data, the low frequency corner of the LT1328
photodiode receiver is set to 14Hz to prevent pulse-top
distortion.
To do this, make C1 4.7µF. 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
additionalprocessingbeyondthatprovidedbytheLT1328.
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.
5V
24"
D2
C5
1
2
3
4
8
7
6
5
HSDL 4220
4.7µF
D1
C6
1000pF
R3
TEMIC
3.9Ω
BPV22NF
R1
100Ω
LT1328
1/2W
5V
NC
C4
4.7µF
Q3
2N7002
C2
4.7µF
R2
10k
BIT ERROR RATE
TRANSMITTER/RECEIVER
375bps NRZ DATA
1328 F05
OUT
IN
Figure 5. Simple NRZ Data Link
7
LT1328
U
W U U
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 line-
operated 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 re-
ceive the 3MHz signal. Thus, the low frequency response
is no longer required and the LT1328 can be configured as
a FIR receiver with no changes. Note that when in FIR/
4ppm mode, the LT1328 has excellent rejection to active-
ballast 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 2.3µs, just under a symbol period. With this modula-
tion, the range can be extended to over 30" and still have
a bit error rate lower than 1 in 108.
5V
1
2
3
4
8
7
6
5
>30"
D1
TEMIC
BPV22NF
C6
D2
C5
1000pF
HSDL 4220
4.7µF
LT1328
R3
3.9Ω
5V
NC
C4
100pF
C2
4.7µF
1/2W
R1
100Ω
Q3
2N7002
R2
10k
R4
R5
C8
100pF
C7
10pF
5k
46.4k 5V
1%
1%
6
7
15
14
1
BIT ERROR RATE
TRANSMITTER/RECEIVER
11
10
74LS00
375bps NRZ DATA
5
2
1
13
2
3
1/2
74LS123
1/2
74LS123
3
OUT
IN
9
3MHz
1328 F06
Figure 6. Simple Data Link with Improved Low Frequency Noise Rejection
U
TYPICAL APPLICATIONS N
Wireless Slave for Photographic Flash
R1
TO HOT SHOE
100Ω
1
2
3
4
8
7
6
5
OF SLAVE FLASH
LIGHT FROM
D1
NC
NC
MASTER FLASH
HAMAMATSU
5V
S4797-01
LT1328
C5
0.1µF
C2
4.7µF
R5
1k
R2
1k
NC
R3
10k
C4
Q1
330pF
MPS2907A
Q2
MPSA42
D2
1N4148
D3
MUR
160524
R4
10k
1328 TA05
8
LT1328
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TYPICAL APPLICATIONS N
9
LT1328
U
PACKAGE DESCRIPTION
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
7
6
5
0.118 ± 0.004**
(3.00 ± 0.10)
0.192 ± 0.004
(4.88 ± 0.10)
1
2
3
4
0.040 ± 0.006
(1.02 ± 0.15)
0.006 ± 0.004
(0.15 ± 0.10)
0.007
(0.18)
0° – 6° TYP
SEATING
PLANE
0.021 ± 0.004
(0.53 ± 0.01)
0.012
(0.30)
0.025
(0.65)
TYP
*
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.
MSOP08 0596
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
10
LT1328
U
PACKAGE DESCRIPTION
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)
7
5
8
6
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
3
4
2
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.050
(1.270)
TYP
0.014 – 0.019
(0.355 – 0.483)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
SO8 0996
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
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 represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LT1328
U
TYPICAL APPLICATIONS N
IrDA Receiver
IrDA Transmitter
JP1
2
V
CC
C6
1000pF
LT1328
SHDN
1
3
1
2
3
4
8
7
6
5
C5
D2
IN
4.7µF
V
D1
BPV22NF*
HSDL-4220*
CC
E2 MODE
FILTER MODE
FILTER
R3
R1
100Ω
5%
3.9Ω
1/2W
C1
10nF
E3 V
CC
V
CC
SWITCH
Q1
E4 DATA
GND
DATA
E6 TRANS
2N7002
*TEMIC
C4
330pF
C2
4.7µF
R2
10k
5%
E1 GND
E5 GND
1328 TA03
*HEWLETT PACKARD
1328 TA04
RELATED PARTS
PART NUMBER
DESCRIPTION
UltraFastTM Precision Comparator
COMMENTS
10ns Prop Delay
12ns Prop Delay
LT1016
LT1116
Single Supply, Ground Sensing Comparator
Multiple Modulation Standard Infrared Receiver
Dual 4mA, 50MHz, 800V/µs Op Amp
LT1319
Supports IrDA, SIR and FIR, Sharp/Newton and TV Remote
C-LoadTM Op Amp Stable with All Capacitive Loads
LT1361
UltraFast and C-Load are trademarks of Linear Technology Corporation.
1328f LT/TP 0597 7K • PRINTED IN USA
Linear Technology Corporation
●
1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900
12
●
●
LINEAR TECHNOLOGY CORPORATION 1997
FAX: (408) 434-0507 TELEX: 499-3977 www.linear-tech.com
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