LT1431
1
1431fe
Typical applicaTion
FeaTures DescripTion
Programmable Reference
The LT
®
1431 is an adjustable shunt voltage regulator
with 100mA sink capability, 0.4% initial reference voltage
tolerance and 0.3% typical temperature stability. On-chip
divider resistors allow the LT1431 to be configured as a
5V shunt regulator, with 1% initial voltage tolerance and
requiring no additional external components. By adding
two external resistors, the output voltage may be set to
any value between 2.5V and 36V. The nominal internal
current limit of 100mA may be decreased by including
one external resistor.
A simplified 3-pin version, the LT1431CZ/LT1431IZ, is
available for applications as an adjustable reference and
is pin compatible with the TL431.
Isolated 5V Regulator
applicaTions
n Guaranteed 0.4% Initial Voltage Tolerance
n 0.1Ω Typical Dynamic Output Impedance
n Fast Turn-On
n Sink Current Capability, 1mA to 100mA
n Low Reference Pin Current
n Available in J8, N8, S8 or 3-Lead TO-92 Z Packages
n Linear Regulators
n Adjustable Power Supplies
n Switching Power Supplies
VREF vs Temperature
LT1431 TA01
COLLCOMPV+
5V
LT1431
GND-FGND-S
RTOP
REF
RMID
2.5V
+
–
gm =
4mA/V
+
SWITCHING
REGULATOR
–
VIN
5V
+
TEMPERATURE (°C)
–50
V
REF
(V)
2.4975
2.5000
2.5025
25 75
LT1431 TA01b
2.4950
2.4925
–25 0 50 100 125
2.4900
2.4875
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
LT1431
2
1431fe
absoluTe MaxiMuM raTings
V+, VCOLLECTOR ..........................................................36V
VCOMP, RTOP, RMID, VREF .............................................6V
GND-F to GND-S ......................................................0.7V
Ambient Temperature Range
LT1431M, LT1431MP ......................... –55°C to 125°C
LT1431I ................................................ –40°C to 85°C
LT1431C .................................................. 0°C TO 70°C
(Note 1)
pin conFiguraTion
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1431CN8#PBF LT1431CN8#TRPBF LT1431 CN8 8-Lead Plastic DIP 0°C to 70°C
LT1431IN8#PBF LT1431IN8#TRPBF LT1431 IN8 8-Lead Plastic DIP –40°C to 85°C
LT1431CS8#PBF LT1431CS8#TRPBF LT1431 8-Lead Plastic SO 0°C to 70°C
LT1431IS8#PBF LT1431IS8#TRPBF LT1431I 8-Lead Plastic SO –40°C to 85°C
LT1431MPS8#PBF LT1431MPS8#TRPBF LT1431 8-Lead Plastic SO –55°C to 125°C
LT1431MJ8#PBF LT1431MJ8#TRPBF LT1431 MJ8 8-Lead CERDIP –55°C to 125°C
LT1431CZ#PBF LT1431CZ#TRPBF LT1431 CZ 3-Lead TO-92 Plastic 0°C to 70°C
LT1431IZ#PBF LT1431IZ#TRPBF LT1431 IZ 3-Lead TO-92 Plastic –40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
Junction Temperature Range
LT1431M, LT1431MP ......................... –55°C to 150°C
LT1431I ..............................................–40°C to 100°C
LT1431C ................................................. 0°C to 100°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec) ...................300°C
1
2
3
4
8
7
6
5
TOP VIEW
COLLECTOR
COMP
V+
RTOP
REF
RMID
GND-F
GND-S
J8 PACKAGE
8-LEAD CERDIP
TJMAX = 150°C, θJA = 100°C/W
1
2
3
4
8
7
6
5
TOP VIEW
COLLECTOR
COMP
V+
RTOP
REF
RMID
GND-F
GND-S
N8 PACKAGE
8-LEAD PLASTIC DIP
TJMAX = 100°C, θJA = 130°C/W
1
2
3
4
8
7
6
5
TOP VIEW
REF
RMID
GND-F
GND-S
COLLECTOR
COMP
V+
RTOP
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 100°C, θJA = 170°C/W
BOTTOM VIEW
REF ANODE
CATHODE
Z PACKAGE
3-LEAD TO-92 PLASTIC
TJMAX = 100°C, θJA = 150°C/W
LT1431
3
1431fe
elecTrical characTerisTics
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: VKA is the cathode voltage of the LT1431CZ/IZ and corresponds
to V+ of the LT1431CN8/IN8/CS8/IS8. IK is the cathode current of the
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. IK = 10mA unless otherwise specified (Note 2)
SYMBOL PARAMETER CONDITIONS
LT1431I, LT1431M LT1431C
UNITSMIN TYP MAX MIN TYP MAX
VREF Reference Voltage VKA = 5V, IK = 2mA, (Note 3)
l
2.490
2.465 2.500 2.510
2.535 2.490
2.480 2.500 2.510
2.520 V
V
∆VREF/∆T Reference Drift VKA = 5V, IK = 2mA l50 30 ppm/°C
∆VREF/∆VKA Voltage Ratio, Reference to
Cathode (Open-Loop Gain) IK = 2mA, VKA = 3V to 36V l0.2 0.5 0.2 0.5 mV/V
|IREF| Reference Input Current VKA = 5V, TA = 25°C
l
0.2 1.0
1.5 0.2 1.0
1.2 µA
µA
IMIN Minimum Operating Current VKA = VREF to 36V 0.6 1.0 0.6 1.0 mA
|IOFF| Off-State Cathode Current VKA = 36V, VREF = 0V
l
1
15 1
2µA
µA
|ILEAK| Off-State Collector Leakage Current VCOLL = 36V, V+ = 5V, VREF = 2.4V
l
1
51
2µA
µA
|ZKA| Dynamic Impedance VKA = VREF, IK = 1mA to 100mA, f ≤ 1kHz 0.2 0.2 Ω
ILIM Collector Current Limit VKA = VREF + 50mV l80 360 100 260 mA
5V Reference Output Internal Divider Used, IK = 2mA 4.950 5.000 5.050 4.950 5.000 5.050 V
LT1431CZ/IZ and corresponds to I(V+) + ICOLLECTOR of the LT1431CN8/
IN8/CS8/IS8.
Note 3: The LT1431 has bias current cancellation which is effective only
for VKA ≥ 3V. A slight (≈2mV) shift in reference voltage occurs when
VKA drops below 3V. For this reason, these tests are not performed at
VKA = VREF.
LT1431
4
1431fe
Typical perForMance characTerisTics
VREF and IREF vs Temperature
ILIMIT vs Temperature with
External Resistor
COLLECTOR VSAT vs
Temperature vs Current
Propagation Delay vs Overdrive
Voltage Gain and Phase
vs Frequency
Transconductance and Phase
vs Frequency (REF to COLL)
2.5V Reference IK vs VKA VREF and IREF vs V +VREF and IREF vs V +
VKA (V)
0
I
K
(µA)
600
800
1000
4.0
LT1431 TPC01
400
200
01.0 2.0 3.0 5.0
IMIN
500
700
900
300
100
0.5 4.5
1.5 2.5 3.5
V+ (V)
2.5
VREF (V)
2.501
2.503
2.505
3.3
LT1431 TPC02
2.499
2.497
2.495 2.7 2.9 3.1 3.5
I
REF
(µA)
1.5
2.5
3.5
0.5
–0.5
–1.5
VREF
IREF
2.500
2.502
2.504
2.498
2.496
3.22.6 2.8 3.0 3.4
1.0
2.0
3.0
0
–1.0
V+ (V)
0
V
REF
(V)
2.501
2.503
2.505
32
LT1431 TPC03
2.499
2.497
2.495 816 24 40
I
REF
(µA)
1.5
2.5
3.5
0.5
–0.5
–1.5
VREF
IREF
2.500
2.502
2.504
2.498
2.496
28
412 20 36
1.0
2.0
3.0
0
–1.0
TEMPERATURE (°C)
–50
V
REF
(V)
2.4975
2.5000
2.5025
25 75
LT1431 TPC04
2.4950
2.4925
–25 0 50 100 125
2.4900
2.4875
0.33
0.66
1.00
0
–0.33
–0.66
–1.00
I
REF
(µA)
VREF
IREF
TEMPERATURE (°C)
–50
LIMIT
1.000
1.125
1.250
25 75
LT1431 TPC05
0.875
0.750
–25 0 50 100 125
0.625
0.500
ILIMIT = 0.7
RLIM + 3.6 AT 25°C
TEMPERATURE (°C)
–50
V
SAT
(V)
0.80
1.00
1.20
25 75
LT1431 TPC06
0.60
0.40
–25 0 50 100 125
0.20
0
ICOLL = 100mA
ICOLL = 20mA
ICOLL = 10mA
ICOLL = 50mA
OVERDRIVE (mV)
0
PROPAGATION DELAY (µs)
90
120
150
200
LT1431 TPC07
60
30
050 100 150 250
75
105
135
45
15
3 1
1k OUTPUT
5 6
5V
LT1431
VREF ± OVERDRIVE
OUTPUT HIGH-TO-LOW
OUTPUT LOW-TO-HIGH
FREQUENCY (Hz)
20
REF-TO-COLL 1k LOAD A
V
(dB)
40
80
120
140
100 10k 100k 10M
LT1431 TPC08
0
1k 1M
100
60
–20
–90
–45
45
135
180
–135
90
0
–180
PHASE (DEG)
PHASE
AV
FREQUENCY (Hz)
1010
100 10k 100k 10M
LT1431 TPC09
1k 1M
–90
–45
45
135
180
–135
90
0
–180
PHASE (DEG)
109
108
107
106
105
104
103
102
REF-TO-COLL g
m
(µ )
Ω
PHASE
gm
LT1431
5
1431fe
Typical perForMance characTerisTics
ICOMP vs VCOMP vs VREF Noise vs Frequency 0.1Hz to 10Hz Noise
Transconductance and Phase
vs Frequency (Ref to Comp) Dynamic Impedance vs Frequency VCOMP vs Temperature vs ICOLL
FREQUENCY (Hz)
104
100 10k 100k 10M
LT1431 TPC10
1k 1M
–100
–80
–40
0
20
–120
–20
–60
–140
PHASE (DEG)
3 × 103
103
0.1
REF-TO-COLL g
m
(µ )
Ω
PHASE
gm
3 × 102
FREQUENCY (Hz)
100
0.8
1.0
1.2
1.4
1k 10k 100k
LT1431 TPC11
0.6
0.4
0.2
0
IK ≤ 100mA
ZKA (Ω)
TEMPERATURE (°C)
–50
V
COMP
(V)
2.0
2.5
3.0
25 75
LT1431 TPC12
1.5
1.0
–25 0 50 100 125
0.5
0
ICOLL = 100mA
ICOLL = 10mA
VCOMP (V)
0
I
COMP
(µA)
400
500
600
1.5 2.5
LT1431 TPC13
300
200
0.5 1.0 2.0 3.0 3.5
100
0
VREF = 5V
VREF = 4V
VREF = 3V
VREF = 2.53V
FREQUENCY (Hz)
NOISE (nV/√Hz)
1000
1 100 1k 100k
LT1431 G14
10 10k
500
0
TIME (MINUTES)
0 3 5
LT1431 TPC15
1 2 4 6
NOISE VOLTAGE (50µV/DIV)
LT1431
6
1431fe
block DiagraM
pin FuncTions
COLL (Pin 1): Open collector of the output transistor. The
maximum pin voltage is 36V. The saturation voltage at
100mA is approximately 1V.
COMP (Pin 2): Base of the driver for the output transis-
tor. This pin allows additional compensation for complex
feedback systems and shutdown of the regulator. It must
be left open if unused.
V+ (Pin 3): Bias voltage for the entire shunt regulator.
The maximum input voltage is 36V and the minimum to
operate is equal to VREF (2.5V). The quiescent current is
typically 0.6mA.
RTOP (Pin 4): Top of the on-chip 5k-5k resistive divider
that guarantees 1% accuracy of operation as a 5V shunt
regulator with no external trim. The pin is tied to COLL for
self-contained 5V operation. It may be left open if unused.
See note on parasitic diodes below.
GND-S (Pin 5): Ground reference for the on-chip resis-
tive divider and shunt regulator circuitry except for the
output transistor. This pin allows external current limit
of the output transistor with one resistor between GND-F
(force) and GND-S (sense).
GND-F (Pin 6): Emitter of the output transistor and sub-
strate connection for the die.
RMID (Pin 7): Middle of the on-chip resistive divider string
between RTOP and GND-S. The pin is tied to REF for self-
contained 5V operation. It may be left open if unused.
REF (Pin 8): Control pin of the shunt regulator with a
2.5V threshold. If V+ > 3V, input bias current cancellation
reduces IB to 0.2µA typical.
COMP, RTOP, RMID, and REF have static discharge protection
circuits that must not be activated on a continuous basis.
Therefore, the absolute maximum DC voltage on these
pins is 6V, well beyond the normal operating conditions.
As with all bipolar ICs, the LT1431 contains parasitic diodes
which must not be forward biased or else anomalous
behavior will result. Pin conditions to be avoided are RTOP
below RMID in voltage and any pin below GND-F in voltage
(except for GND-S).
The following pin definitions apply to the Z package.
CATHODE: Corresponds to COLL and V+ tied together.
ANODE: Corresponds to GND-S and GND-F tied together.
REF: Corresponds to REF.
LT1431 BD
COMPV
+
GND-FORCE
GND-SENSE
RTOP
REF
RMID
2.5V
+
–
gm =
4mA/V
5k
COLLECTOR
8
7
5
4 3 2 1
6
5k
LT1431
7
1431fe
applicaTions inForMaTion
Typical applicaTions
Frequency Compensation
As a shunt regulator, the LT1431 is stable for all capacitive
loads on the COLL pin. Capacitive loading between 0.01µF
and 18µF causes reduced phase margin with some ringing
under transient conditions. Output capacitors should not
be used arbitrarily because output noise is not necessar-
ily reduced.
Excess capacitance on the REF pin can introduce enough
phase shift to induce oscillation when configured as a
reference >2.5V. This can be compensated with capacitance
between COLL and REF (phase lead). More complicated
feedback loops may require shaping of the frequency
response of the LT1431 with dominant pole or pole-zero
compensation. This can be accomplished with a capacitor
or series resistor and capacitor between COLL and COMP.
The compensation schemes mentioned above use voltage
feedback to stabilize the circuits. There must be voltage gain
at the COLL pin for them to be effective, so the COLL pin
must see a reasonable AC impedance. Capacitive loading
of the COLL pin reduces the AC impedance, voltage gain,
and frequency response, thereby decreasing the effective-
ness of the compensation schemes, but also decreasing
their necessity.
2.5V Reference
3-Pin Package
2.5V Reference
8-Pin Package 5V Reference
Increasing 5V Reference
Programmable Reference with Adjustable
Current Limit
VIN
R
L
2.5V
LT1431 TA02
CATHODE
REF
LT1431Z
ANODE
VIN
R
L
2.5V
LT1431 TA03
COLL
REF
LT1431
GND-F
V+
GND-S
VIN
R
L
5V
LT1431 TA04
COLL
REF
LT1431
GND-F
V+
GND-S
RTOP
RMID
VIN
R
L
5V + ∆
LT1431 TA05
R
∆ = R • (0.5mA) ±25% PROCESS TOLERANCE
∆ ≤ 500mV
COLL
REF
LT1431
GND-F
V+
GND-S
RTOP
RMID
VIN
R
L
LT1431 TA06
RLIM
VOUT =
( )
1 + R1
R2 VREF
R1
R2
ILIMIT = 0.7
RLIM + 3.6 AT 25°C
COLL
REF
LT1431
GND-F
V+
GND-S
LT1431
8
1431fe
Typical applicaTions
PNP Low Dropout 5V Regulator*
FET Low Dropout 5V Regulator with Current Limit
0.015µF
150Ω
LT1431 TA07
COLL
REF
LT1431
GND-F
COMP
GND-S
V+
RMID
RTOP
2 1
5 6
8
7
20Ω**
2W 47Ω
1k
5V
330µF
0.1µF
V
IN
3
4
MEASURED DROPOUT VOLTAGE
420mV AT 4A
190mV AT 2A
95mV AT 1A
60mV AT 0.5A
*NO SHORT-CIRCUIT PROTECTION
**MAY BE INCREASED AT LOWER WATTAGE
FOR LOWER OUTPUT CURRENTS
+
MJE2955
2N2219
1.5k
LT1431 • TA08
8
7
3
4
5 6
1
COLL
REF
LT1431
GND-FGND-S
V+
RMID
RTOP
1N4148
7
6
LT1006
2 3
–+4
5
0.002Ω*
47µF
MTP50N05EL
MTM25N05L
D S
G
VIN ≥ 5.2V
47µF
5V, 2.5A
12V
ILOAD
2A
1A
0.5A
MTP50N05EL
47mV
22mV
11.5mV
MTM25N05L
145mV
73mV
37mV
*1.5" #23 SOLID COPPER WIRE
~0.002Ω → 3A LIMIT
Measured Dropout Voltages
+ +
LT1006
LT1431
9
1431fe
Typical applicaTions
Isolated 5V to ±15V Flyback Converter Fully Loaded Output Ripple vs Filtering
12V to 5V Buck Converter with Foldback Current Limit* Buck Converter Efficiency
2
COLL
REF
GND-F
COMP
GND-S
V+
RMID
RTOP
1
1500pF
5 6
8
7
3
4
5k
VIN VOUT
GNDLOGIC IN
VIN LT1089
HI-SIDE SWITCH
MBR735 100Ω
0.5W
PULSE ENGINEERING
#PE-51515
5V, 7A
3300µF
*CONTACT LTC FOR HIGH EFFICIENCY
SWITCHING REGULATORS
LT1431 TA09
LT1431
+
ILOAD (A)
0
EFFICIENCY (%)
60
70
80
3 5 8
LT1431 TA10
50
40
30 1 2 46 7
VIN = 9V
VIN = 12V
VIN = 15V
3
5 6
8
1
2
V+
REF
GND-FGND-S
COLL
COMP
2.4k
0.1µF 20k
13.3k
2.7k
VOUT
VC
GND
VIN
LT1172
OR
LT1072
1.5k
0.68µF
3k
0.47µF
50µF
4.5V
TO 5.5V
MUR105
4, 5
•
6, 7
•
2
10
•
9MUR105
C* 15k
MUR105
C*
–15V, 70mA
15V, 70mA
COILTRONICS
CTX02-11934
MEASURED EFFICIENCY
LT1172 67.8% AT 2.2WOUT
LT1072 68.6% AT 2.2WOUT
LT1071 61.1% AT 4.4WOUT
LT1431 TA11
1
LT1431
+
+
+
4N36
210µF
100µF 100µF
C* LT1172
30mVP-P
LT1072
40mVP-P
6mVP-P 8mVP-P
L*
*L BELL INDUSTRIES J.W. MILLER
DIVISION 9310-36 10µH, 450mA
LT1431 TA12
+
++
LT1431
10
1431fe
Typical applicaTions
5V Power Supply Monitor with ±500mV
Window and 50mV Hysteresis Transfer Function
High Efficiency Buck Converter E = 85% to 89%
COLL
REF
GND-F
V+
GND-S
10Ω**
“HIGH” FOR
OVER VOLTAGE OR
UNDER VOLTAGE
5k
1N4148
COLL
REF
GND-F
V+
GND-S
10Ω**
5k
4k*1k6k*1k
*DETERMINES WINDOW SIZE
V = (R – 5k)(0.5mA)
**SETS HYSTERESIS
LT1431 TA13
LT1431 LT1431
VIN
0
0
V
OUT
1
2
3
4
6
12 3 4
LT1431 TA14
5 6
5
COLL
12
65
REF
RMID
3
Q3
2N3904
4
8
7
V+
RTOP
R8*
24.9k
COMP
GND-FGND-S
LT1431CN8
+
+
+R2
1k
C3
0.1µF
C5
0.047µF
C4
0.033µF
R6*
23.7k
5V
2.5A
C6
470µF
16V
0.12Ω
ESR
R7*
24.9k
1431 TA15
Q2
2N3904
D2
BAT85
D4
BAT85
R1
470k
C2
4.7µF
35V
TANT L1
50µH 3A
R5
680Ω
Q1
VN2222LL
RUN = 0
SHUTDOWN > 3V
R4
100Ω
R3
10k
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTANCES ARE IN Ω, 0.25W, 5%
2. ALL CAPACITANCES ARE IN µF, 50V, 10%
3. SHUTDOWN LOGIC STATE MUST BE DEFINED BY A LOGIC GATE OR BY TYING TO GND
1
2
RTN
OFF
1
VIN
D1
BAT85
C1
220µF
35V
D3
MBR330
BOLD LINES INDICATE HIGH CURRENT PATHS
*1% FILM RESISTORS
C1: NICHICON UPL1V221MPH
C3, C4, C5: WIMA MKS-2
C6: NICHICON UPL1C471MPH6
D1, D2: PHILIPS BAT85
D3: MOTOROLA MBR330
L1: COILTRONICS CTX50-3-MP
LT1170
VIN
VC
GND
VSW
FB
3 1
2
4
5
LT1431
11
1431fe
scheMaTic DiagraM
package DescripTion
Q9
R1
35k
R2
35k
Q5
Q1 Q2
8
REF
4
RTOP
7
RMID
5
GND-SENSE
R4
5k
R3
5k
R5
5k R8
600Ω
R21
100k
R10
340Ω
R14
11Ω R18
50k R19
3.6Ω
Q7 Q13
Q6
R6
8.5k
Q17
COMP
2COLLECTOR
1
Q14
Q4
C1
22pF R12
1k
C2
65pF R13
6.5k
R11
11k
10X
Q15 Q16 Q21
2.5X
6
GND-FORCE
C4
1pF
R17
1.5k
R15
5k
2X
R20
5k
45X
C3
6pF
LT1431 SD01
V
+
3
R9
2.5k
R7
2.5k
Q22
Q20
Q8
2X
5X
4X 3X
R16
11Ω
Q3 Q11
Q12
Q10
Q18 Q19
J8 Package
8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
J8 0801
.014 – .026
(0.360 – 0.660)
.200
(5.080)
MAX
.015 – .060
(0.381 – 1.524)
.125
3.175
MIN
.100
(2.54)
BSC
.300 BSC
(7.62 BSC)
.008 – .018
(0.203 – 0.457) 0° – 15°
.045 – .065
(1.143 – 1.651)
.045 – .068
(1.143 – 1.650)
FULL LEAD
OPTION
.023 – .045
(0.584 – 1.143)
HALF LEAD
OPTION
CORNER LEADS OPTION
(4 PLCS)
.005
(0.127)
MIN
.405
(10.287)
MAX
.220 – .310
(5.588 – 7.874)
1 2 34
8 7 6 5
.025
(0.635)
RAD TYP
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
LT1431
12
1431fe
N8 1002
.065
(1.651)
TYP
.045 – .065
(1.143 – 1.651)
.130 ± .005
(3.302 ± 0.127)
.020
(0.508)
MIN
.018 ± .003
(0.457 ± 0.076)
.120
(3.048)
MIN
.008 – .015
(0.203 – 0.381)
.300 – .325
(7.620 – 8.255)
.325 +.035
–.015
+0.889
–0.381
8.255
()
12 34
87 65
.255 ± .015*
(6.477 ± 0.381)
.400*
(10.160)
MAX
NOTE:
1. DIMENSIONS ARE INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
.100
(2.54)
BSC
package DescripTion
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030 ±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
LT1431
13
1431fe
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
D 4/10 M-grade parts re-released. Obsolete package shading removed. 2, 11
E 7/11 Added LT1431MPS8 to data sheet. Changes reflected throughout. 1 to 14
(Revision history begins at Rev D)
LT1431
14
1431fe
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 1992
LT 0711 REV E • PRINTED IN USA
relaTeD parTs
Z Package
3-Lead Plastic TO-92 (Similar to TO-226)
(Reference LTC DWG # 05-08-1410 Rev C)
package DescripTion
.050
(1.27)
BSC
.060 ± .005
(1.524± 0.127)
DIA
.90
(2.286)
NOM
.180 ± .005
(4.572 ± 0.127)
.180 ± .005
(4.572 ± 0.127)
.500
(12.70)
MIN
.050
(1.270)
MAX
UNCONTROLLED
LEAD DIMENSION
.016 ± .003
(0.406 ± 0.076)
5°
NOM
BULK PACK
.015 ± .002
(0.381 ± 0.051)
.060 ± .010
(1.524 ± 0.254)
10° NOM
.140 ± .010
(3.556 ± 0.127)
Z3 (TO-92) 1008 REV C
3 2 1
.098 +.016/–.04
(2.5 +0.4/–0.1)
2 PLCS
TO-92 TAPE AND REEL
REFER TO TAPE AND REEL SECTION OF
LTC DATA BOOK FOR ADDITIONAL INFORMATION
PART NUMBER DESCRIPTION COMMENTS
LT4430 Secondary-Side Optocoupler Driver with Reference
Voltage Overshoot Control Prevents Output Overshoot during Start-Up and
Short-Circuit Recovery
LT3757/LT3758 Boost, Flyback, SEPIC and Inverting Controller 2.9V/5.5V ≤ VIN ≤ 40V/100V, 100kHz to 1MHz Fixed Frequency,
3mm × 3mm DFN-10 and MSOP-10E Packages
LTC3803/LTC3803-3/
LTC3803-5 Flyback DC/DC Controller with Fixed 200kHz or 300kHz
Operating Frequency VIN and VOUT Limited by External Components, 6-Pin ThinSOT™
Package
LTC3873/LTC3873-5 No RSENSE Constant Frequency Flyback, Boost, SEPIC
Controller VIN and VOUT Limited Only by External Components, 8-Pin ThinSOT and
2mm × 3mm DFN-8 Packages
LTC3805/LTC3805-5 Adjustable Constant Frequency (70KHz to 700kHz)
Frequency Flyback DC/DC Controller VIN and VOUT Limited by External Components, MSOP-10E and
3mm × 3mm DFN-10 Packages
LT1952/LT1952-1 Isolated Synchronous Forward Controllers Ideal for Medium Power 24V and 48V Input Applications
LTC3723-1/LTC3723-2 Synchronous Push-Pull and Full-Bridge Controllers High Efficiency with On-Chip MOSFET Drivers
LTC3721-1/LTC3721-2 Non-Synchronous Push-Pull and Full-Bridge Controllers Minimizes External Components, On-Chip MOSFET Drivers
LTC3722/LTC3722-2 Synchronous Isolated Full Bridge Controllers Ideal for High Power 24V and 48V Input Applications