SAP datasheet(3/6 Pages) SANKEN

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Di VF

TR VBE

Variations

VBE

VBE Min.

(P and N: hFE Max.)

VBE Max.

(P and N: hFE Min.)

40mA

∆VF=500mV

2. External Variable Resistor

Total forward voltage (at IF =2.5mA) of the diodes is designed to be equal or less than that of total VBE (at IC

= 40mA) of the transistor, thus the idling current is required to be adjusted at 40mA with an additional

external variable resistor.

The relations are shown as below:

Total VF of Diode

Total VBE of Transistor + Total VRE of Emitter Resistor

∆V=0 to 500mV

The VBE of the transistor is dependent to the hFE, and the VBE is lower with higher hFE and vice versa. The

hFE for both the PNP and the NPN varies between 5k and 20k; thus the VBE is the lowest with the

combination of maximum hFE (20k) each and it is the highest with the combination of minimum hFE (5k)

each.

Presuming the voltage difference between the VF of the diodes and the VBE of the transistors (including the

total voltage drops of the two emitter resistors) as

∆V.

Minimum VBE – Maximum VF variations of the diodes = 0

Maximum VBE – Minimum VF variations of the diodes = 500mV

The current flowing over the diodes and the VR is adjusted at 2.5mA; therefore

500mV

2.5mA = 200

Ω

Consequently, the applicable VR value is to be 0 to 200

Ω

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