GAMMA GM431BT92B

GM431
2.5V ADJUSTABLE
SHUNT REGULATOR
Description
Features
The GM431is a three terminal adjustable shunt
regulator with thermal stability guaranteed over
temperature. The output voltage can be adjusted
to any value between 2.5V (VREF) and 18V by
using two external resistors. The GM431 has a
typical dynamic output impedance of 0.2 . Active
output circuitry provides a very unique turn on
characteristic, making the GM431an excellent
replacement for zener diodes in many
applications such as on board regulation and
adjustable power supplies. The GM431 is an
ideal voltage reference for 3.0 to 3.3V switching
power supplies.
‹
Sink Current Capability 1mA to 100mA
‹
Low dynamic out put impedance, 0.2
typ.
‹
Low output noise
‹
0.5%, 1% or 2% reference voltage
tolerance
‹
Alternate for TL431, LM431 & AS431
‹
Temperature range -40°C to + 125°C
‹
Available in SOT-23, TO-92, SOT-89 and
Sop- 8 packages
The GM431 shunt regulator is available with 3
voltage tolerances 0.5%, 1.0% and 2.0% over
full temperature range and four package options
(SOT-23, TO-92, SOT-89 and SO-8).
Application
Switching power supplies
Battery-operated computers
Linear regulator
Computer disk drives
Adjustable supplies
Instrumentation
Logic Symbol
Block Diagram
Cathode
Reference
Cathode
Reference
VREF
Anode
www.gammamicro.com.tw
GM431V1.07
Anode
1
GM431
2.5V ADJUSTABLE
SHUNT REGULATORS
Marking Information and Pin Configurations (Top View)
SOT23
SOT89
AAXYW
3
Cathode
431G
AYWW
431G
AYWW
Ref 1
Ref 1
2
3 Cathode
Anode
(GM431)
Anode
2
RAXYW
1
Cathode
3
Ref
(GM431R)
GM431V1.07
AAX: Marking Code (see table below)
RAX: Marking Code (see table below)
G: Grade Code (A: 0.5%, B: 1.0%, C: 2.0%)
A: Assembly/Test Site Code
Y: Year
W: Week code
WW: Week
2
SO8
6. Anode
7. Anode
8. Ref
Anode
2
1
Ref
TO92
5. NC
GM431G
AYWW
3 Cathode
2
Anode
1. Cathode
2. Anode
4. NC
3. Anode
GM431
2.5V ADJUSTABLE
SHUNT REGULATOR
Ordering Information
Precision Device Code
Grade
Package
Shipping
GM431AT92B
0.5%
A
TO-92
1,000 Units/ESD Bag
GM431AT92RL
0.5%
A
TO-92
2,000 Units/Ammo Pack (Tape)
GM431AST23R
0.5%
AAA
SOT-23
3,000 Units/Tape & Reel
GM431RAST23R
0.5%
RAA
SOT-23
3,000 Units/Tape & Reel
GM431AS8T
0.5%
A
SO-8
100 Units/Tube
GM431AS8R
0.5%
A
SO-8
2,500 Units/Tape & Reel
GM431AST89R
0.5%
A
SOT-89
1,000 Units/Tape & Reel
GM431BT92B
1.0%
B
TO-92
1,000 Units/ESD Bag
GM431BT92RL
1.0%
B
TO-92
2,000 Units/Ammo Pack (Tape)
GM431BST23R
1.0%
AAB
SOT-23
3,000 Units/Tape & Reel
GM431RBST23R
1.0%
RAB
SOT-23
3,000 Units/Tape & Reel
GM431BS8T
1.0%
B
SO-8
100 Units/Tube
GM431BS8R
1.0%
B
SO-8
2,500 Units/Tape & Reel
GM431BST89R
1.0%
B
SOT-89
1,000 Units/Tape & Reel
GM431CT92B
2.0%
A
TO-92
1,000 Units/ESD Bag
GM431CT92RL
2.0%
C
TO-92
2,000 Units/Ammo Pack (Tape)
GM431CST23R
2.0%
AAC
SOT-23
3,000 Units/Tape & Reel
GM431RCST23R
2.0%
RAC
SOT-23
3,000 Units/Tape & Reel
GM431CS8T
2.0%
C
SO-8
100 Units/Tube
GM431CS8R
2.0%
C
SO-8
2,500 Units/Tape & Reel
GM431AST89R
2.0%
C
SOT-89
1,000 Units/Tape & Reel
GM431V1.07
Ordering Number
3
GM431
2.5V ADJUSTABLE
SHUNT REGULATORS
Absolute Maximum Ratings
PARAMETER
Cathode Voltage
Continuous Cathode Current Range
Reference Input Current Range
Power Dissipation at TA = 25°C
SOT-23
TO-92
SOT-89
SO-8
Package Thermal Resistance
SOT-23
TO-92
SOT-89
SO-8
Operating Ambient Temperature Range
Storage Temperature
Lead Temperature (soldering 10 sec.)
SYMBOL
RATINGS
UNITS
VKA
IK
IREF
20
-100 to 150
-50µA to 10mA
V
mA
PD
0.23
0.78
0.8
0.6
W
336
132
132
163
-40 - 125
- 65 to 150
260
θJA
TA
°C/W
°C
°C
°C
Recommended Operating Conditions
PARAMETER
Cathode Voltage
Cathode Current
SYMBOL
Min
Max
UNITS
VKA
IK
VREF
10
18
100
V
mA
Equivalent Schematics
Cathode
800
800
20pF
Reference
3.28K
4K
GM431V1.07
10k
4
2.4K
7.2K
20pF
1K
Anode
GM431
2.5V ADJUSTABLE
SHUNT REGULATOR
Electrical Characteristics (TA = 25°C unless otherwise specified)
Parameter
Symbol
Condition
GM431A
Reference
Voltage
GM431B
VREF
VKA = VREF, IK = 10mA,
Test circuit 1
GM431C
VREF Deviation over
Temperature
Ratio of change in VREF
to change in VKA
Reference Input
Current
VREF(DEV)
∆VREF/∆VKA
Min
Typ
Max
2.488
2.500
2.513
2.475
2.500
2.525
2.450
2.500
2.550
4
17
VKA = VREF, IK = 10mA, Full Range
Test circuit 1
IK = 10mA
∆VKA = 10V to VREF
-2.7
-1.0
∆VKA = 18V to 10V
-2
-0.4
Unit
mV
mV
µA
IREF
IK = 10mA, R1 = 10K, R2 = ∞
Test circuit 2
1.3
4
µA
IREF Deviation over
Temperature
VREF(DEV)
IK = 10mA, R1 = 10K, R2 = ∞
Full range, Test circuit 2
0.4
1.2
µA
Minimum Cathode
Current
IK(MIN)
VKA = VREF
Test circuit 1
0.4
1.0
mA
Off-state cathode
Current
IK(OFF)
VKA = 18V, VREF = 0V
Test circuit 3
0.1
1
µA
Dynamic Impedance
|ZKA|
VKA = VREF, IK = 1mA to 10mA,
f ≤1kHz, Test circuit 1
0.2
0.5
Ω
VKA
VIN
Test Circuits
VIN
IK
VKA
IK
R1
VIN
VKA
IK(OFF)
IREF
VREF
Test Circuit 1
VKA = VREF
R2
VREF
Test Circuit 2
VKA > VREF
Test Circuit 3
Off-State
GM431V1.07
VREF
5
GM431
2.5V ADJUSTABLE
SHUNT REGULATORS
Cathode current (mA)
Typical Characteristics
200
2.5
150
2
Impedance
100
50
0
-50
1.5
1
0.5
-100
0
-150
-2
-1
0
2
1
Cathode Voltage (V)
3
IREF, Reference Input Current (mA))
Figure 5. Cathode Current vs.
Cathode Voltage
0.6
0.5
0.4
0.3
0.2
0.1
0
-40
-20
0 20 40 60 80 100 120
TA Ambient Temperature (˚C)
GM431V1.07
VREF, Reference Input Voltage (V)
Figure 6. Reference Input Current vs.
Ambient Temperature
6
2.500
2.498
2.496
2.494
2.492
2.490
2.488
2.486
-40
-20
0 20 40 60 80 100 120
TA Ambient Temperature (˚C)
Figure 8. Reference Input Voltage vs.
Ambient Temperature
0
100K
200K 300K 400K 500K 600K
Frequency (Hz)
Figure 7. Dynamic Impedance
GM431
2.5V ADJUSTABLE
SHUNT REGULATOR
Design Guide for AC-DC SMPS (Switching Mode Power Supply)
Use of Shunt Regulator in Transformer Secondary side control
This example is applicable to both forward transformers and flyback transformers. A Shunt regulator is
used on the secondary side as an error amplifier, and feedback to the primary side is provided via a
photo-coupler.
Transformer
R1
SBD
R3
GM384X
series
(+)
IF
VF
Phototransistor
IB
R2
C1
Light Emitting
Diode
Output
VO
R5
GM431
(-)
VREF
R4
Figure 9. Typical Shunt Regulator/ Error Amplifier
Determination of external constants for the Shunt Regulator
DC Characteristic determination: In the application circuit above, R1 and R2 are protection resistors
for the light emitting diode in the photo-coupler, and R2 is a bypass resistor to feed IK Minimum, and
these are determined as shown below. The photo-coupler specification should be obtained separately
from the manufacturer. Using the parameters in this circuit, the following formulas are obtained:
R1 =
V O – VF - V K
IF + IB
VF
R2 = I
B
VK is the GM431 operating voltage, and is set at around 3V, taking into account a margin for fluctuation.
R2 is the current shunt resistance for the 1ight emitting diode, in which a bias current IB of around 1/5 IF
f1ows.
Next, the output voltage can be determined by R3 and R4, and the following formula is obtained:
R3 + R4
R4 )
VREF = 2.5V Typical
The abSo1ute va1ueS of R3 and R4 are determined by the GM431 reference input current IREF and the
AC characteristics described in the next Section. The IREF va1ue is around 0.7µA Typ.
GM431V1.07
VO = VREF (
7
GM431
2.5V ADJUSTABLE
SHUNT REGULATORS
AC Characteristic Determination:
This refers to the determination of the gain frequency characteristic of the Shunt regulator as an error
amp1ifier. Taking the configuration in Figure 10, the error amp1ifier characteristic is as Shown in Figure
10.
G1
Gain G (dB)
* fOSC: PWM Switching frequency
G2
When R5= 0
F1
FAC
F2
When R5= 0
fOSC Frequency f (Hz)
Figure 10. GM431 Error Amplification Characteristic
In Figure 17, the following formulas are obtained:
Gain
G1 = G0 ≅ 50 dB to 60 dB (determined by shunt regulator)
R5
G2 = R
3
Corner frequencies
f1 = 1/(2pC1G0R3)
f2 = 1/(2pC1R5)
G0 iS the Shunt regulator open-loop gain; this is given by the reciprocal of the reference voltage
fluctuation:
∆VREF/∆VKA, and is approximately 50 dB.
Practical Example
Consider the example of a photocoupler, with an internal light emitting diode VF = 1.05 V and IF = 2.5mA,
power supply output vo1tage V2 = 5V, and bias resistance R2 current of approximately 1/5 IF at 0.5mA.
If the Shunt regulator VK = 3V, the following values are found.
GM431V1.07
5V – 1.05V – 3V
R1 = 2.5mA + 0.54mA = 316Ω
8
1.05V
R2 = 0.54mA = 2.1kΩ
Next, assume that R3 = R4 = 10k. This gives a 5V output. If R5 = 3.3 k, and C1 = 0.022 pF, the
following values are found.
G2 = 3.3kΩ / 10kΩ = 0.33 times (-10 dB)
f1 = 1 / (2 × π × 0.022µF × 316 × 10 k) = 2.3 (Hz)
f1 = 1 / (2 × π × 0.022µF × 3.3k) = 2.2 (kHz) 2
GM431
2.5V ADJUSTABLE
SHUNT REGULATOR
Package Outline Dimensions – SOT 23
0.110 - 0.120
(2.80 - 3.04)
0.003 - 0.007
(0.08 - 0.18)
0.013 - 0.017
(0.34 - 0.44)
0.013 - 0.017
(0.34 - 0.44)
0.083 - 0.104
(2.11 - 2.62)
0.047 - 0.055
(1.20 - 1.40)
0 - 8 typ
0.075
Typ.
(1.91)
0.037
(0.93) Typ.
0.0150 - 0.0200
(0.382 - 0.508)
0.0005 - 0.0040
(0.025 - 0.102)
Package Outline Dimensions – SOT 89
0.173 - 0.181
(4.39 - 4.59)
0.061 REF
(1.550 REF)
0.084 - 0.090
(2.13 - 2.28)
0.155 - 0.167
(3.94 - 4.24)
0.055 - 0.063
(1.39 - 1.60)
0.014 - 0.017
(0.35 - 0.43)
0.090 - 0.102
(2.28 - 2.59)
8
0.035 - 0.047
(0.89 - 1.19)
0.016 - 0.023
(0.400 - 0.580)
0.013 - 0.021
(0.320 - 0.520)
0.059 BSC
(1.49) BSC
GM431V1.07
0.118 BSC
(2.99) BSC
9
GM431
2.5V ADJUSTABLE
SHUNT REGULATORS
Package Outline Dimensions – TO 92
3.85 - 4.19
4.7 - 5.2
4.9 - 5.2
12.7 - 14.2
0.4 - 0.55
Typ.
1.22 - 1.32
2.10 - 2.27
Dimensions are in millimeters
Package Outline Dimensions – SO 8
0.189 - 0.197
(4.800 - 5.004)
0.228 - 0.244
(5.791 - 6.198)
0.016 - 0.050
(0.406 - 0.270)
D
0.014 - 0.020
(0.356 - 0.508)
0.050
(1.270)
TYP
0.150 - 0.157
(3.810 - 3.988)
0.053 - 0.059
(1.346 - 1.753)
GM431V1.07
SEATING PLAN
10
0.004 - 0.010
(0.012 - 0.254)
0.008 - 0.010
(0.203 - 0.254)
8.0
MAX
GM431
2.5V ADJUSTABLE
SHUNT REGULATOR
Ordering Number
GM 431 A
APM
Gamma
Micro
Circuit
Type
T92
R
Output
Accuracy
Package Type
Shipping Type
A: 0.5%
B: 1.0%
C: 2.0%
T92: TO-92
ST23:SOT-23
ST89: SOT-89
S8: SO-8
B: Bag
RL: Ammo Pack (Tape)
T: Tube
R: Tape & Reel
ST23
R
Output
Accuracy
Package Type
Shipping Type
A: 0.5%
B: 1.0%
C: 2.0%
ST23:SOT-23
R: Tape & Reel
GM 431R A
APM
Gamma
Micro
Circuit
Type
GM431V1.07
Ordering Number
1
1
1