SEMICONDUCTOR
AS2431Reference Precision Adjustable Shunt
Description
The AS2431 is a three-terminal adjustable shunt regulator providing a highly accurate bandgap reference. The adjustable shunt regulator is ideal for a wide variety of linear applications that can be implemented using external components to obtain adjustable currents and voltages. In the standard shunt configuration, the combination of low temperature coefficient (TC), sharp turn-on characteristics, low output impedance and programmable output voltage make this precision reference an excellent error amplifier. The AS2431 is a direct replacement for the AS431 in low voltage, low current applications. It is also available in the very small footprint SOT23.
Features
• • • • • • Temperature-compensated: 15 ppm/°C Trimmed bandgap reference Internal amplifier with 100 mA capability Multiple temperature ranges Low frequency dynamic output impedance: < 450 mΩ Low output noise
Pin Configuration –
Top View
TO-92 (LP)
CATHODE CATHODE ANODE ANODE REFERENCE ANODE N/C
2 3 4 1
8L SOIC (8D)
8 7 6 5
REFERENCE ANODE ANODE N/C
SOT-89 (S) 3L SOT-23 (3VS)
CATHODE CATHODE ANODE REFERENCE ANODE REFERENCE
Ordering Information
AS2431 A C 8D N
Circuit Type: Precision Adjustable Shunt Regulator Bandgap Tolerance: A = ±0.25% C = ±0.5% D = ±1.0% E = ±2.0% Temperature Range: A = 0°C to 70°C B = 0°C to 105°C C = –40°C to +85°C F = –55°C to +125°C Packaging Option: A = Ammo Pack B = Bulk T = Tube M = Tape and Reel (7" Reel Dia. SOT-23 Only) N = Tape and Reel (13" Reel Dia) Package Style: 8D = 8 Pin, Plastic SOIC LP = TO-92 S = SOT-89 3VS = 3 Pin, SOT-23
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AS2431
Functional Block Diagram
Precision Adjustable Shunt Reference
CATHODE (K)
REFERENCE (R)
+ –
2.5 V
ANODE (A)
Absolute Maximum Ratings
Parameter Cathode-Anode Reverse Breakdown Anode-Cathode Forward Current Operating Cathode Current Reference Input Current Continuous Power Dissipation at 25°C TO-92 8L SOIC SOT-89 3L SOT-23 Junction Temperature Storage Temperature Lead Temp, Soldering 10 Seconds TJ TSTG TL Symbol VKA IAK IKA IREF PD 775 750 1000 200 150 –65 to 150 300 mW mW mW mW °C °C °C Rating 18 1 100 1 Units V A mA mA
Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
Recommended Conditions
Parameter Cathode Voltage Cathode Current Symbol VKA IK Rating VREF to 18 10 Unit V mA
Typical Thermal Resistances
Package TO-92 SOIC SOT-89 θJA 160°C/W 175°C/W 110°C/W θJC 80°C/W 45°C/W 8°C/W 150°C/W Typical Derating 6.3 mW/°C 5.7 mW/°C 9.1 mW/°C 1.7 mW/°C
SOT-23/5L 575°C/W
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AS2431
Average Temperature Coefficient
ppm mV
Precision Adjustable Shunt Reference
0
0
0 ∆VREF ∆T –10
• TC in mV/°C =
∆VREF (mV) ∆TA ∆VREF
%
5000
0.5
• TC in %/°C =
VREF at 25°C ∆TA ∆VREF
X 100
–20
0
15
30
45 60 75 Temperature (°C)
90
105
• TC in ppm/°C =
VREF at 25°C ∆TA
X 106
0.07 mV/°C 0.003%/°C 27 ppm/°C
Test Circuits
VIN VKA = VREF VIN VKA VIN VKA
IREF
IK
IK R1 IREF (VREF) R2
IK (OFF)
Figure 1a. Test Circuit 1
Figure 1b. Test Circuit 2
Figure 1c. Test Circuit 3
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Precision Adjustable Shunt Reference
Typical Performance Curves
AS2431
Low Current Operating Characteristics
900 800 700 IK – Cathode Current (mA) 600 IK – Cathode Current (µA) 500 400 300 200 100 0 –100 –200 –1.0 0 1.0 2.0 3.0 125°C 25°C –55°C VKA = VREF Temperature Range: –55 to 125°C 150 125 100 75 50 25 0 –25 –50 –75 –100 –2
High Current Operating Characteristics
VKA = VREF Temperature Range: –55 to 125°C
–1
0
1
2
3
VKA – Cathode Voltage (V)
VKA – Cathode Voltage (V)
Figure 2
Figure 3
Off State Leakage
100 VKA = 18 V VREF = 0 V IZ off – Off State Cathode Current (nA) VREF – Reference Voltage (V) 10 3.53 2.52 2.51 2.50 2.49 2.48 2.47 2.46 0.01 –60 2.45 –60
Reference Voltage vs Ambient Temperature
VKA = VREF IK = 10 mA
VREF = 2.500 V at 25°C
1
0.1
–30
0
30
60
90
120
–30
0
30
60
90
120
TA – Ambient Temperature (°C)
TA – Ambient Temperature (°C)
Figure 4
Figure 5
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AS2431
Typical Performance Curves
Precision Adjustable Shunt Reference
Reference Input Current
3.0 R1 = 10 kΩ R2 = ∞ IK =10 mA 0
Reference Voltage Line Regulation
–30°C ∆VREF – Change in Reference Voltage (mV) –5
2.5 IREF – Reference Input Current (µA)
2.0
–10 25°C –15 75°C –20 IK = 10 mA Temperature Range: –55 to 125°C –25 0 3 6 9 12 15 125°C
1.5
1.0
0.5
0 –60
–30
0
30
60
90
120
18
TA – Ambient Temperature (°C)
VKA – Cathode Voltage (V)
Figure 6
Figure 7
Noise Voltage
70 60 VKA = VREF IK = 10 mA TA = 25°C ZKA – Dynamic Impedance (Ω) 0.150
Low Frequency Dynamic Output Impedance
VKA = VREF IKA = 1 to 100 mA f ≤ 1 kHz
0.125
50 Noise Voltage nV/√Hz
0.100
40 30
0.075
20
0.050
10 0 10 100 1k f – Frequency (Hz) 10 k 100 k
0.025
0.0 –60
–30
0
30
60
90
120
TA – Free Air Temperature
Figure 8
Figure 9
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Precision Adjustable Shunt Reference
Typical Performance Curves
AS2431
Dynamic Output Impedance
100 TA = 25°C IK = 1 to 100 mA ZKA – Dynamic Impedance (Ω) 10
1.0
0.1
0.01 1k
10 k
100 k f – Frequency (Hz)
1M
10 M
Figure 10
Small Signal Voltage Gain vs. Frequency
70 Temperature Range: –55 to 125°C 60 AV – Small Signal Voltage Gain (dB) IK = 10 mA 50 40 30 8.25 k GND 20 10 0 1k 9 µF 15 k IK OUT 230 Ω
10 k
100 k f – Frequency (Hz)
1M
10 M
Figure 11
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AS2431
Typical Performance Curves
Precision Adjustable Shunt Reference
Pulse Response
6 Input 5 Input and Output Votages (V) 4 3 2 1 GND 0 –1 0 1 2 3 4 5678 t – Time (ms) 9 10 11 12 Output fP = 100 kHz INPUT MONITOR 220 Ω OUT
50 Ω
Figure 12
Stability Boundary Conditions
100 90 80 IK – Cathode Current (mA) 70 60 50 40 30 20 10 0 100 TA = 25°C B D 101 102 103 104 105 106 107 Stability Region CL A 10 K C IK A: VKA = VREF B: VKA = 5 V at IK = 10 mA C: VKA = 10 V at IK = 10 mA D: VKA = 15 V at IK = 10 mA
150 Ω
CL – Load Capacitance (pF)
Figure 13
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