TL431 shunt reference
TL431 shunt reference with explicit circuit assumptions and worked equations.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Set point: VKA = Vref(1 + Rt/Rb) + Iref Rt
Cathode current: IKA = (Vin − VKA)/Rbias − Iload − (Vref/Rb + Iref)
Assumptions
- Minimum cathode current and maximum current are user-specified device constraints, not inferred from family name. TL431/TLV431 choices set nominal reference voltage only. Output is the intended regulated voltage; it is not valid when minimum cathode current is missed. Load-capacitance stability must be checked against the exact part, cathode current and voltage curves.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Reference
- tl431
- Custom reference voltage
- 2.5 V
- Top feedback resistor
- 10000 Ω
- Bottom feedback resistor
- 10000 Ω
- Reference pin current
- 0.000002 A
- Minimum supply
- 12 V
- Maximum supply
- 15 V
- Maximum external load
- 0.005 A
- Required minimum cathode current
- 0.001 A
- Maximum allowed cathode current
- 0.1 A
- Supply bias resistor
- 1000 Ω
- Load capacitance
- 0 F
Results
- Regulated cathode voltage
- 5.01 V
- Minimum bias resistance
- 99.6494 Ω
- Maximum bias resistance
- 1118.13 Ω
- Cathode current at min supply/max load
- 0.0017385 A
- Cathode current at max supply/no load
- 0.0097385 A
- Maximum cathode power
- 0.0487899 W