TL431-Q1 Datasheet, PDF (4/26 Pages) Texas Instruments – ADJUSTABLE PRECISION SHUNT REGULATOR

TL431−Q1
ADJUSTABLE PRECISION SHUNT REGULATOR
SGLS302D − MARCH 2005 − REVISED MARCH 2013
electrical characteristics over recommended operating conditions, T_A = 25°C (unless otherwise
noted)
V_ref
V_I(dev)
DV_ref
DV_KA
I_ref
I_I(dev)
I_min
I_off
|z_KA|
PARAMETER
TEST
CIRCUIT
TEST CONDITIONS
Reference voltage
Deviation of reference voltage
over full temperature range
(see Figure 1)
2
V_KA = V_ref, I_KA = 10 mA
2
V_KA = V_ref, I_KA = 10 mA,
T_A = −40°C to 125°C
Ratio of change in reference voltage
to the change in cathode voltage
3
I_KA = 10 mA
ΔV_KA = 10 V − V_ref
ΔV_KA = 36 V − 10 V
Reference current
3
I_KA = 10 mA, R1 = 10 kΩ, R2 = ∞
Deviation of reference current
over full temperature range
(see Figure 1)
3
I_KA = 10 mA, R1 = 10 kΩ, R2 = ∞,
T_A = −40°C to 125°C
Minimum cathode current
for regulation
2
V_KA = V_ref
Off-state cathode current
Dynamic impedance (see Figure 1)
4
V_KA = 36 V, V_ref = 0
1
I_KA = 1 mA to 100 mA, V_KA = V_ref,
f ≤ 1 kHz
TL431BQ
MIN TYP MAX
2483 2495 2507
UNIT
mV
14
34 mV
−1.4 −2.7 _mV
−1
−2 V
2
4 μA
0.8 2.5 μA
0.4 0.7 mA
0.1 0.5 μA
0.2 0.5 Ω
The deviation parameters, V_ref(dev) and I_ref(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, α_Vref, is defined as:
Ť Ť _{ǒ Ǔ} ^{ǒ Ǔ} _aVref
VI(dev)
ppm
°C
+
Vref at 25°C
DT_A
10⁶
Maximum V_ref
Minimum V_ref
V_I(dev)
ΔT_A
where:
ΔT_A is the recommended operating free-air temperature range of the device.
a_{Vref can be positive or negative, depending on whether minimum Vref or maximum Vref, respectively, occurs at the}
lower temperature.
Example: maximum V_ref = 2496 mV at 30°C, minimum V_ref = 2492 mV at 0°C, V_ref = 2495 mV at 25°C,
ΔT_A = 70°C for TL431
Ť Ť _aVref
+
ǒ 4 mV Ǔ
2495 mV
70°C
10⁶
[
23 ppm
°C
Because minimum V_ref occurs at the lower temperature, the coefficient is positive.
Calculating Dynamic Impedance
The dynamic impedance is defined as:
|z_KA|
+
DV_KA
DI_KA
When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit
is given by:
ǒ Ǔ |z_Ȁ|
+
DV
DI
[
|z_KA|
1
)
R1
R2
Figure 1. Calculating Deviation Parameters and Dynamic Impedance
4
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