TYN608 SCR (Thyristor)

15 March 2020 - 0 Comments

TYN608 SCR (Thyristor)

TYN608 SCR Pinout

The TYN608 is a standard 8A SCR available in a TO-220AB package that can be used to control medium power AC/DC loads and can handle high current surges.

Pin configuration

Pin number:	Pin name:	Pin description:
1	Cathode	Conventional current flows out of the cathode.
2	Anode	Conventional current flows into the anode.
3	Gate	Controls conduction between the anode and cathode.
4	Tab	Electrically connected to the anode.

Features

Maximum anode-cathode voltage (off state): 600V
Maximum RMS current: 8A
Pulsed DC current: 100A
Gate trigger current: 15mA max.
Holding current: 30mA max.
Latching current: 70mA max.
Available in the TO-220AB package.

Note: Complete Technical Details can be found in the TYN608 datasheet available at the end of this page.

TYN608 equivalent SCRs: BT152, BT151, 2N6508

Other SCRs: BTA16, BT136, BTB12600B, S6010

TYN608 SCR Overview

The TYN608 is a medium power SCR used in power circuits. SCRs are latching diodes controlled by a small current through the gate terminal. Despite being specified for 100A pulsed, a deeper look into the datasheet tells us that higher current peaks are possible. The I_TSM/t_p graph clearly shows this:

TYN608 Maximum Peak Current VS Pulse Duration Graph

The graph intersects 100A at 5ms but then continues to increase to a maximum peak current of 800A at 50us. Careful use can enable the device to reach these currents.

How to use the TYN608 SCR

One very useful circuit that can be made using an SCR is an inrush current limiter. Off-line switching supplies have a bridge rectifier at the input which converts AC to DC and feeds a large electrolytic filter capacitor. When the capacitor is discharged and the supply is connected to the mains, a large inrush current flows through the rectifier to charge the capacitor, which could lead to component failure.

TYN608 Inrush Current Limitter

In the Figure shown above, an SCR and a resistor are used to solve this problem. Initially, the SCR is in the off state, so inrush current is limited by the resistor. Once the capacitor is charged, the SCR is triggered so that the current can be sustained under load.