adjustable precision shunt regulators

Transkript

TL431C, TL431AC, TL431I, TL431AI, TL431M, TL431Y
ADJUSTABLE PRECISION SHUNT REGULATORS
SLVS005I – JULY 1978 – REVISED AUGUST 1998
D
D
D
D
D
D
D PACKAGE
(TOP VIEW)
Equivalent Full-Range Temperature
Coefficient . . . 30 ppm/°C
0.2-Ω Typical Output Impedance
Sink-Current Capability . . . 1 mA to 100 mA
Low Output Noise
Adjustable Output Voltage . . . Vref to 36 V
Available in a Wide Range of High-Density
Packages
CATHODE
ANODE
ANODE
NC
8
2
7
3
6
4
5
REF
ANODE
ANODE
NC
JG, P, OR PW PACKAGE
(TOP VIEW)
description
CATHODE
NC
NC
NC
The TL431 and TL431A are 3-terminal adjustable
shunt regulators with specified thermal stability
over applicable automotive, commercial, and
military temperature ranges. The output voltage
can be set to any value between Vref
(approximately 2.5 V) and 36 V with two external
resistors (see Figure 17). These devices have a
typical output impedance of 0.2 Ω. Active output
circuitry provides a very sharp turn-on
characteristic, making these devices excellent
replacements for Zener diodes in many
applications, such as on-board regulation,
adjustable power supplies, and switching power
supplies.
1
8
2
7
3
6
4
5
REF
NC
ANODE
NC
PK PACKAGE
(TOP VIEW)
REF ANODE CATHODE
LP PACKAGE
(TOP VIEW)
The TL431C and TL431AC are characterized for
operation from 0°C to 70°C, and the TL431I and
TL431AI are characterized for operation from
–40°C to 85°C. The TL431M is characterized for
operation over the full military temperature range
of –55°C to 125°C.
CATHODE
ANODE
REF
KTP PACKAGE
(TOP VIEW)
NC
CATHODE
NC
REF
NC
FK PACKAGE
(TOP VIEW)
4
3 2 1 20 19
18
5
17
6
16
7
15
8
14
9 10 11 12 13
CATHODE
ANODE
ANODE
REF
NC
NC
NC
ANODE
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
1
NC – No internal connection
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright  1998, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
On products compliant to MIL-PRF-38535, all parameters are tested
unless otherwise noted. On all other products, production
processing does not necessarily include testing of all parameters.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
1
AVAILABLE OPTIONS
PACKAGED DEVICES
TA
SMALL
OUTLINE
(D)
0°C
to
70°C
TL431CD
TL431ACD
–40°C
to
85°C
TL431ID
TL431AID
–55°C
to
125°C
CHIP
CARRIER
(FK)
TL431MFK
CERAMIC
DIP
(JG)
PLASTIC
FLANGE
MOUNT
(KTP)
TO-226AA
(LP)
PLASTIC
DIP
(P)
SOT-89
(PK)
SHRINK
SMALL
OUTLINE
(PW)
TL431CKTPR
TL431CLP
TL431ACLP
TL431CP
TL431ACP
TL431CPK
TL431CPW
TL431ILP
TL431AILP
TL431IP
TL431AIP
TL431IPK
CHIP
FORM
(Y)
TL431Y
TL431MJG
The D and LP packages are available taped and reeled. Add R suffix to device type (e.g., TL431CDR). The KTP and PK packages are only available
taped and reeled. Chip forms are tested at TA = 25°C.
symbol
REF
ANODE
CATHODE
functional block diagram
CATHODE
+
REF
_
Vref
ANODE
2
equivalent schematic†
CATHODE
800 Ω
800 Ω
20 pF
REF
150 Ω
3.28 kΩ
2.4 kΩ
7.2 kΩ
4 kΩ
10 kΩ
20 pF
1 kΩ
800 Ω
ANODE
† All component values are nominal.
3
TL431Y chip information
This chip, when properly assembled, displays characteristics similar to those of the TL431C. Thermal
compression or ultrasonic bonding can be used on the doped-aluminum bonding pads. The chip can be
mounted with conductive epoxy or a gold-silicon preform.
Bonding Pad Assignments
(1)
CATHODE
(1)
(2)
ANODE
TL431Y
(3)
REF
41
(3)
(2)
Chip Thickness: 15 Mils Typical
Bonding Pads: 4 × 4 Mils Minimum
TJ(max) = 150°C
Tolerances Are ±10%.
All Dimensions Are in Mils.
Pins 2, 3, 6, and 7 Are Connected Together.
Pins 4 and 5 Are Not Connected.
51
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Cathode voltage, VKA (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 V
Continuous cathode current range, IKA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –100 mA to 150 mA
Reference input current range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –50 µA to 10 mA
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Tables 1 and 2
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
Case temperature for 60 seconds: FK package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds: D, P, or PW package . . . . . . . . . . . . 260°C
Lead temperature 1,6 mm (1/16 inch) from case for 60 seconds: JG, LP, or PK package . . . . . . . . . . 300°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: Voltage values are with respect to the anode terminal unless otherwise noted.
4
DISSIPATION RATING TABLE 1 – FREE-AIR TEMPERATURE
PACKAGE
TA = 25°C
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
TA = 70°C
POWER RATING
TA = 85°C
POWER RATING
TA = 125°C
POWER RATING
D
725 mW
5.8 mW/°C
464 mW
377 mW
—
FK
1375 mW
11 mW/°C
880 mW
715 mW
275 mW
JG
1050 mW
8.4 mW/°C
672 mW
546 mW
210 mW
KTP
1800 mW
14.5 mW/°C
1147 mW
943 mW
—
LP
775 mW
6.2 mW/°C
496 mW
403 mW
—
P
1000 mW
8 mW/°C
640 mW
520 mW
—
PK
500 mW
4 mW/°C
320 mW
260 mW
—
PW
525 mW
4.2 mW/°C
336 mW
—
—
DISSIPATION RATING TABLE 2 – CASE TEMPERATURE
PACKAGE
TC = 25°C
POWER RATING
DERATING FACTOR
ABOVE TC = 25°C
TC = 70°C
POWER RATING
TC = 85°C
POWER RATING
PK
3125 mW
25 mW/°C
2000 mW
1625 mW
recommended operating conditions
Cathode voltage, VKA
Cathode current, IKA
C suffix
Operating free-air temperature range, TA
MIN
MAX
Vref
1
36
V
100
mA
0
70
I suffix
–40
85
M suffix
–55
125
UNIT
°C
5
electrical characteristics over recommended operating conditions, TA = 25°C (unless otherwise
noted)
TEST
CIRCUIT
PARAMETER
TEST CONDITIONS
IKA = 10 mA
TL431C
UNIT
MIN
TYP
MAX
2440
2495
2550
mV
4
25
mV
–1.4
–2.7
–1
–2
mV
V
Vref
Reference voltage
2
VKA = Vref,
VI(dev)
Deviation of reference voltage
over full temperature range
(see Figure 1)
2
VKA = Vref, IKA = 10 mA,
TA = Full range†
DVref
DVKA
Ratio of change
g in reference voltage
g
to the change in cathode voltage
3
IKA = 10 mA
Iref
Reference current
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞
2
4
µA
II(dev)
Deviation of reference current
(see Figure 1)
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞,
TA = Full range†
0.4
1.2
µA
Imin
Minimum cathode current
for regulation
2
VKA = Vref
0.4
1
mA
Ioff
Off-state cathode current
4
0.1
1
µA
|zKA|
Dynamic impedance (see Figure 1)
1
VKA = 36 V,
Vref = 0
IKA = 1 mA to 100 mA, VKA = Vref,
f ≤ 1 kHz
0.2
0.5
Ω
∆VKA = 10 V – Vref
∆VKA = 36 V – 10 V
† Full temperature range is 0°C to 70°C for the TL431C.
The deviation parameters Vref(dev) and Iref(dev) are defined as the differences between the maximum and minimum
values obtained over the recommended temperature range. The average full-range temperature coefficient of the
reference voltage, αVref, is defined as:
Ťa
ǒ Ǔ
Ť ǒ Ǔ+
Maximum Vref
V
Vref
I(dev)
V at 25°C
ref
ppm
°C
10
VI(dev)
6
DTA
Minimum Vref
∆TA
where:
∆TA is the recommended operating free-air temperature range of the device.
αVref can be positive or negative, depending on whether minimum Vref or maximum Vref, respectively, occurs at the
lower temperature.
Example: maximum Vref = 2496 mV at 30°C, minimum Vref = 2492 mV at 0°C, Vref = 2495 mV at 25°C,
∆TA = 70°C for TL431C
Ťa Ť + ǒ
4 mV
2495 mV
Vref
Ǔ
70°C
10 6
[ 23 ppmń°C
Because minimum Vref occurs at the lower temperature, the coefficient is positive.
Calculating Dynamic Impedance
The dynamic impedance is defined as: |z KA|
+ DDVI
KA
KA
When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit
is given by:
DV |zKA| 1 R1
|z |
DI
R2
Ȁ+ [
ǒ) Ǔ
Figure 1. Calculating Deviation Parameters and Dynamic Impedance
6
noted)
PARAMETER
TEST
CIRCUIT
TEST CONDITIONS
IKA = 10 mA
TL431I
UNIT
MIN
TYP
MAX
2440
2495
2550
mV
5
50
mV
–1.4
–2.7
–1
–2
mV
V
Vref
Reference voltage
2
VKA = Vref,
VI(dev)
(see Figure 1)
2
TA = Full range†
DVref
DVKA
Ratio of change
g
3
IKA = 10 mA
Iref
Reference current
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞
2
4
µA
II(dev)
(see Figure 1)
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞,
TA = Full range†
0.8
2.5
µA
Imin
Minimum cathode current for
regulation
2
VKA = Vref
0.4
1
mA
Ioff
4
0.1
1
µA
|zKA|
2
VKA = 36 V,
Vref = 0
f ≤ 1 kHz
0.2
0.5
Ω
∆VKA = 36 V – 10 V
† Full temperature range is –40°C to 85°C for the TL431I.
noted)
PARAMETER
TEST
CIRCUIT
TEST CONDITIONS
Vref
Reference voltage
2
VKA = Vref,
VI(dev)
(see Figure 1)
IKA = 10 mA
2
TA = Full range†
DVref
DVKA
Ratio of change
g
3
IKA = 10 mA
Iref
Reference current
3
II(dev)
(see Figure 1)
Imin
∆VKA = 36 V – 10 V
TL431M
MIN
TYP
MAX
2400
2495
2600
22
UNIT
mV
mV
–1.4
–3
–1
–2.3
mV
V
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞
2
8*
µA
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞,
TA = Full range‡
1
for regulation
2
VKA = Vref
0.4
1.5
mA
Ioff
4
0.1
3
µA
|zKA|
1
VKA = 36 V,
Vref = 0
f ≤ 1 kHz
0.2
0.9*
Ω
µA
* On products compliant to MIL-PRF-38535, this parameter is not production tested.
‡ Full temperature range is –55°C to 125°C for the TL431M.
7
noted)
TEST
CIRCUIT
PARAMETER
TEST CONDITIONS
IKA = 10 mA
TL431AC
UNIT
MIN
TYP
MAX
2470
2495
2520
mV
4
25
mV
–1.4
–2.7
–1
–2
mV
V
Vref
Reference voltage
2
VKA = Vref,
VI(dev)
(see Figure 1)
2
TA = Full range†
DVref
DVKA
Ratio of change
g
3
IKA = 10 mA
Iref
Reference current
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞
2
4
µA
II(dev)
(see Figure 1)
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞,
TA = Full range†
0.8
1.2
µA
Imin
for regulation
2
VKA = Vref
0.4
0.6
mA
Ioff
4
0.1
0.5
µA
|zKA|
1
VKA = 36 V,
Vref = 0
f ≤ 1 kHz
0.2
0.5
Ω
∆VKA = 36 V – 10 V
† Full temperature range is 0°C to 70°C for the TL431AC.
noted)
TEST
CIRCUIT
PARAMETER
TEST CONDITIONS
IKA = 10 mA
UNIT
MIN
TYP
MAX
2470
2495
2520
mV
5
50
mV
–1.4
–2.7
–1
–2
mV
V
Vref
Reference voltage
2
VKA = Vref,
VI(dev)
(see Figure 1)
2
TA = Full range†
DVref
DVKA
Ratio of change
g
3
IKA = 10 mA
Iref
Reference current
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞
2
4
µA
II(dev)
(see Figure 1)
3
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞,
TA = Full range‡
0.8
2.5
µA
Imin
for regulation
2
VKA = Vref
0.4
0.7
mA
Ioff
4
0.1
0.5
µA
|zKA|
2
VKA = 36 V,
Vref = 0
f ≤ 1 kHz
0.2
0.5
Ω
∆VKA = 36 V – 10 V
‡ Full temperature range is –40°C to 85°C for the TL431AI.
8
TL431AI
noted)
TEST
CIRCUIT
PARAMETER
Vref
Reference voltage
DVref
DVKA
Ratio of change
g
3
Iref
Reference input current
Imin
for regulation
Ioff
|zKA|
VKA = Vref,
MIN
TYP
MAX
UNIT
IKA = 10 mA
2495
mV
–1.4
–1
mV
V
3
∆VKA = 36 V – 10 V
IKA = 10 mA, R1 = 10 kΩ, R2 = ∞
2
µA
2
VKA = Vref
0.4
mA
4
0.1
µA
Dynamic impedance†
2
VKA = 36 V,
Vref = 0
f ≤ 1 kHz
0.2
Ω
† Calculating dynamic impedance:
2
TL431Y
TEST CONDITIONS
IKA = 10 mA
Ť Ť + DD
V KA
I KA
When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit is given by:
The dynamic impedance is defined as: z
KA
[ |z
Ȁ + ∆V
∆I
|z |
KA
ǒ) Ǔ
| 1
R1
R2
PARAMETER MEASUREMENT INFORMATION
Input
VKA
Input
VKA
IKA
IKA
Vref
R1
Iref
R2
Vref
Figure 2. Test Circuit for VKA = Vref
V KA
+V
ǒ ) Ǔ)
ref
1
R1
R2
I ref
R1
Figure 3. Test Circuit for VKA > Vref
Input
VKA
Ioff
Figure 4. Test Circuit for Ioff
9
TYPICAL CHARACTERISTICS
Table 1. Graphs
FIGURE
Reference input voltage vs Free-air temperature
5
Reference input current vs Free-air temperature
6
Cathode current vs Cathode voltage
7, 8
Off-state cathode current vs Free-air temperature
9
Ratio of delta reference voltage to change in cathode voltage vs Free-air temperature
10
Equivalent input noise voltage vs Frequency
11
Equivalent input noise voltage over a 10-second period
12
Small-signal voltage amplification vs Frequency
13
Reference impedance vs Frequency
14
Pulse response
15
Stability boundary conditions
16
Table 2. Application Circuits
FIGURE
10
Shunt regulator
17
Single-supply comparator with temperature-compensated threshold
18
Precision high-current series regulator
19
Output control of a 3-terminal fixed regulator
20
High-current shunt regulator
21
Crowbar circuit
22
Precision 5-V 1.5-A regulator
23
Efficient 5-V precision regulator
24
PWM converter with reference
25
Voltage monitor
26
Delay timer
27
Precision current limiter
28
Precision constant-current sink
29
REFERENCE VOLTAGE
vs
FREE-AIR TEMPERATURE†
REFERENCE CURRENT
vs
2600
5
VKA = Vref
IKA = 10 mA
R1 = 10 kΩ
R2 = ∞
IKA = 10 mA
Vref = 2550 mV‡
2560
I ref – Reference Current – µ A
V ref – Reference Voltage – mV
2580
2540
2520
Vref = 2495 mV‡
2500
2480
2460
Vref = 2440 mV‡
2440
4
3
2
1
2420
2400
–75
–50
–25
0
25
50
75
100
0
–75
125
TA – Free-Air Temperature – °C
† Data is applicable only within the recommended operating free-air
temperature ranges of the various devices.
‡ Data is for devices having the indicated value of Vref at IKA = 10 mA,
TA = 25°C.
–50
–25
50
75
100
125
Figure 6
CATHODE CURRENT
vs
CATHODE VOLTAGE
CATHODE CURRENT
vs
CATHODE VOLTAGE
150
800
VKA = Vref
TA = 25°C
VKA = Vref
TA = 25°C
100
I KA – Cathode Current – µ A
I KA – Cathode Current – mA
25
Figure 5
125
0
75
50
25
0
–25
–50
600
Imin
400
200
0
–75
–100
–2
–200
–1
0
2
1
3
–1
VKA – Cathode Voltage – V
0
1
2
3
VKA – Cathode Voltage – V
Figure 7
Figure 8
11
RATIO OF DELTA REFERENCE VOLTAGE TO
DELTA CATHODE VOLTAGE
vs
OFF-STATE CATHODE CURRENT
vs
– 0.85
VKA = 36 V
Vref = 0
VKA = 3 V to 36 V
– 0.95
2
∆V ref / ∆V KA – mV/V
I off – Off-State Cathode Current – µ A
2.5
1.5
1
0.5
0
–75
–1.05
–1.15
–1.25
–1.35
–50
–25
0
25
50
75
100
–1.45
–75
125
–50
–25
Figure 10
EQUIVALENT INPUT NOISE VOLTAGE
vs
FREQUENCY
260
Vn – Equivalent Input Noise Voltage – nV/ Hz
25
IO = 10 mA
TA = 25°C
240
220
200
180
160
140
120
100
10
100
1k
10 k
f – Frequency – Hz
Figure 11
50
75
100
125
Figure 9
12
0
100 k
EQUIVALENT INPUT NOISE VOLTAGE
OVER A 10-SECOND PERIOD
V n – Equivalent Input Noise voltage – µV
6
5
4
3
2
1
0
–1
–2
–3
f = 0.1 to 10 Hz
IKA = 10 mA
TA = 25°C
–4
–5
–6
0
1
2
3
4
5
6
7
8
9
10
t – Time – s
19.1 V
1 kΩ
500 µF
910 Ω
2000 µF
VCC
TL431
(DUT)
820 Ω
+
VCC
1 µF
TLE2027
AV = 10 V/mV
+
–
16 kΩ
16 Ω
160 kΩ
16 kΩ
1 µF
TLE2027
To Oscilloscope
22 µF
–
33 kΩ
AV = 2 V/V
0.1 µF
33 kΩ
VEE
VEE
Figure 12. Test Circuit for Equivalent Input Noise Voltage
13
SMALL-SIGNAL VOLTAGE AMPLIFICATION
vs
FREQUENCY
A V – Small-Signal Voltage Amplification – dB
60
IKA = 10 mA
TA = 25°C
50
Output
15 kΩ
IKA
232 Ω
40
9 µF
+
30
–
8.25 kΩ
20
GND
10
0
1k
TEST CIRCUIT FOR VOLTAGE AMPLIFICATION
10 k
100 k
1M
10 M
Figure 13
REFERENCE IMPEDANCE
vs
FREQUENCY
|z KA | – Reference Impedance – Ω
100
IKA = 10 mA
TA = 25°C
1 kΩ
Output
10
IKA
50 Ω
–
+
GND
1
TEST CIRCUIT FOR REFERENCE IMPEDANCE
0.1
1k
10 k
100 k
1M
10 M
Figure 14
14
PULSE RESPONSE
6
TA = 25°C
Input
Input and Output Voltage – V
5
220 Ω
Output
4
Pulse
Generator
f = 100 kHz
3
50 Ω
Output
GND
2
TEST CIRCUIT FOR PULSE RESPONSE
1
0
–1
0
1
2
3
4
5
6
7
t – Time – µs
Figure 15
STABILITY BOUNDARY CONDITIONS†
100
I KA – Cathode Current – mA
90
80
A VKA = Vref
B VKA = 5 V
C VKA = 10 V
D VKA = 15 Vf
150 Ω
TA = 25°C
IKA
+
VBATT
CL
B
–
70
Stable
60
C
Stable
50
A
TEST CIRCUIT FOR CURVE A
40
30
D
IKA
20
10
0
0.001
150 Ω
R1 = 10 kΩ
CL
+
0.01
0.1
1
10
R2
CL – Load Capacitance – µF
–
† The areas under the curves represent conditions that may cause the
device to oscillate. For curves B, C, and D, R2 and V+ were adjusted
to establish the initial VKA and IKA conditions with CL = 0. VBATT and
CL were then adjusted to determine the ranges of stability.
VBATT
TEST CIRCUIT FOR CURVES B, C, AND D
Figure 16
15
APPLICATION INFORMATION
R
(see Note A)
VI(BATT)
VO
R1
0.1%
Vref
TL431
VO
R2
0.1%
ǒ Ǔ
+ 1 ) R1
V
R2
ref
RETURN
NOTE A: R should provide cathode current ≥1 mA to the TL431 at minimum VI(BATT).
Figure 17. Shunt Regulator
VI(BATT)
VO
TL431
Von ≈ 2 V
Voff ≈ VI(BATT)
Input
VIT ≈ 2.5 V
GND
Figure 18. Single-Supply Comparator With Temperature-Compensated Threshold
VI(BATT)
R
(see Note A)
2N222
2N222
30 Ω
0.01 µF
VO
4.7 kΩ
TL431
ǒ Ǔ
+ 1 ) R1
V
R2
VO
R2
0.1%
R1
0.1%
NOTE A: R should provide cathode current ≥1 mA to the TL431 at minimum VI(BATT).
Figure 19. Precision High-Current Series Regulator
16
ref
VI(BATT)
IN
uA7805
OUT
Common
VO
R1
TL431
ǒ Ǔ
+ 1 ) R1
V
R2
Minimum V + V ) 5 V
VO
ref
ref
O
R2
Figure 20. Output Control of a 3-Terminal Fixed Regulator
VI(BATT)
VO
R1
VO
ǒ Ǔ
+ 1 ) R1
V
R2
ref
TL431
R2
Figure 21. High-Current Shunt Regulator
VI(BATT)
VO
R1
TL431
R2
C
(see Note A)
NOTE A: Refer to the stability boundary conditions in Figure 16 to determine allowable values for C.
Figure 22. Crowbar Circuit
17
IN
VI(BATT)
LM317
8.2 kΩ
OUT
Adjust
VO ≈ 5 V, 1.5 A
243 Ω
0.1%
TL431
243 Ω
0.1%
Figure 23. Precision 5-V 1.5-A Regulator
VO ≈ 5 V
VI(BATT)
Rb
(see Note A)
27.4 kΩ
0.1%
TL431
27.4 kΩ
0.1%
NOTE A: Rb should provide cathode current ≥1-mA to the TL431.
Figure 24. Efficient 5-V Precision Regulator
12 V
VCC
6.8 kΩ
5V
10 kΩ
–
10 kΩ
0.1%
TL431
10 kΩ
0.1%
+
X
Not
Used
TL598
Feedback
Figure 25. PWM Converter With Reference
18
R3
(see Note A)
VI(BATT)
R4
(see Note A)
R1B
R1A
TL431
R2A
ǒ Ǔ
ǒ Ǔ
V
+ 1 ) R1B
R2B
High Limit + 1 ) R1A V
R2A
Low Limit
ref
ref
LED on When Low Limit < VI(BATT) < High Limit
R2B
NOTE A: R3 and R4 are selected to provide the desired LED intensity and cathode current ≥1 mA to the TL431 at the available VI(BATT).
Figure 26. Voltage Monitor
650 Ω
12 V
2 kΩ
R
TL431
Off
Delay
+R
C
In
ǒ
Ǔ
*
12 V
12 V V ref
C
On
Figure 27. Delay Timer
RCL
0.1%
VI(BATT)
R1
TL431
IO
I out
+ RV ) I
R1
+
ref
CL
KA
V I(BATT)
I
O
h FE
)I
KA
Figure 28. Precision Current Limiter
19
VI(BATT)
IO
IO
TL431
+ VR
ref
S
RS
0.1%
Figure 29. Precision Constant-Current Sink
20
IMPORTANT NOTICE
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any product or service without notice, and advise customers to obtain the latest version of relevant information
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pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO
BE FULLY AT THE CUSTOMER’S RISK.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
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Copyright  1998, Texas Instruments Incorporated

adjustable precision shunt regulators

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