
LM431
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SNVS020G –MAY 2000–REVISED APRIL 2013
LM431 Electrical Characteristics
TA= 25°C unless otherwise specified
Symbol Parameter Conditions Min Typ Max Units
VREF Reference Voltage VZ= VREF, II= 10 mA 2.440 2.495 2.550 V
LM431A (Figure 4 )
VZ= VREF, II= 10 mA 2.470 2.495 2.520 V
LM431B (Figure 4 )
VZ= VREF, II= 10 mA 2.485 2.500 2.510 V
LM431C (Figure 4 )
VDEV Deviation of Reference Input Voltage Over VZ= VREF, II= 10 mA, 8.0 17 mV
Temperature(1) TA= Full Range (Figure 4 )
ΔVREF/ΔVZRatio of the Change in Reference Voltage IZ= 10 mA VZfrom VREF to 10V −1.4 −2.7 mV/V
to the Change in Cathode Voltage (Figure 5 )VZfrom 10V to 36V −1.0 −2.0
IREF Reference Input Current R1= 10 kΩ, R2=∞, II= 10 mA 2.0 4.0 μA
(Figure 5 )
∝IREF Deviation of Reference Input Current over R1= 10 kΩ, R2=∞, II= 10 mA, 0.4 1.2 μA
Temperature TA= Full Range (Figure 5 )
IZ(MIN) Minimum Cathode Current for Regulation VZ= VREF(Figure 4 )0.4 1.0 mA
IZ(OFF) Off-State Current VZ= 36V, VREF = 0V (Figure 6) 0.3 1.0 μA
rZDynamic Output Impedance(2) VZ= VREF, LM431A, 0.75 Ω
Frequency = 0 Hz (Figure 4 )
VZ= VREF, LM431B, LM431C 0.50 Ω
Frequency = 0 Hz (Figure 4 )
(1) Deviation of reference input voltage, VDEV, is defined as the maximum variation of the reference input voltage over the full temperature
range.
The average temperature coefficient of the reference input voltage, ∝VREF, is defined as:
Where:
T2−T1= full temperature change (0-70°C).
VREF can be positive or negative depending on whether the slope is positive or negative.
Example: VDEV = 8.0 mV, VREF = 2495 mV, T2−T1= 70°C, slope is positive.
(2) The dynamic output impedance, rZ, is defined as:
When the device is programmed with two external resistors, R1 and R2, (see Figure 5 ), the dynamic output impedance of the overall
circuit, rZ, is defined as:
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