Datasheet TL431, TL431A, TL432, TL432A (Texas Instruments) - 6

SLVS005V − JULY 1978 − REVISED NOVEMBER 2003
electrical characteristics over recommended operating conditions, TA = 25
°
C (unless otherwise noted) TEST TL431C, TL432C TEST PARAMETER P TEST CONDITIONS UNIT CIRCUIT MIN TYP MAX
Vref Reference voltage 2 VKA = Vref, IKA = 10 mA 2440 2495 2550 mV Deviation of reference voltage V V KA = Vref, IKA = 10 mA, I(dev) over full temperature range 2 4 25 mV T (see Figure 1) A = 0°C to 70°C DV Ratio of change in reference voltage ∆VKA = 10 V − Vref −1.4 −2.7 ref 3 I mV KA I = 10 mA DV to the change in cathode voltage KA ∆V V KA KA = 36 V − 10 V −1 −2 Iref Reference current 3 IKA = 10 mA, R1 = 10 kΩ, R2 = ∞ 2 4 µA Deviation of reference current I I KA = 10 mA, R1 = 10 kΩ, R2 = ∞, I(dev) over full temperature range 3 0.4 1.2 µA T (see Figure 1) A = 0°C to 70°C Minimum cathode current Imin 2 V for regulation KA = Vref 0.4 1 mA Ioff Off-state cathode current 4 VKA = 36 V, Vref = 0 0.1 1 µA I |z KA = 1 mA to 100 mA, VKA = Vref, KA| Dynamic impedance (see Figure 1) 1 0.2 0.5 Ω f ≤ 1 kHz 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:
Maximum Vref
ǒ VI(dev) Ǔ 106
V
V at 25°C
I(dev)
Ť ref a Ť ǒppmǓ +
Minimum Vref
Vref °C DTA ∆
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 ǒ 4 mV Ǔ Ť 106 a Ť + 2495 mV [ 23 ppmń°C Vref 70°C Because minimum Vref occurs at the lower temperature, the coefficient is positive.
Calculating Dynamic Impedance
Ť Ť DVKA The dynamic impedance is defined as: z + KA DIKA When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit is given by: |zȀ| + DV Ť ǒ Ǔ D [ Ťz 1 ) R1 I KA R2
Figure 1. Calculating Deviation Parameters and Dynamic Impedance
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