AN303 datasheet(8/13 Pages) STMICROELECTRONICS

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Latching current – the details

AN303

8/13

Doc ID 3654 Rev 3

2.3.3

Typical variation of IL with junction temperature

The latching current is physically related to the triggering gate current IGT. These two

parameters vary with the junction temperature as shown in Figure 9.

Figure 9.

Relative variation of IL with the junction temperature Tj

Example

With a BTA12-600C,

IL (QI) = 20 mA (measured) at Tj = 25 °C, then IL (QI) ≈ 32.5 mA at Tj = – 40 °C.

2.3.4

Influence of the external gate-cathode resistor

In some applications, an RGK resistor is connected between the gate and the cathode of the

component. This resistor either improves device behavior under fast transient voltages (by-

pass for A2-G leakage current) in the case of sensitive SCRs or forms part of the triggering

circuit. The value of this resistor, as well as the sensitivity of the component, affects the

latching current as shown in Figure 10.

Figure 10.

Variation of IL, for a sensitive SCR with RGK

IL[RGK] / IL[RGK = 1 kΩ]

0.01

0.10

1.00

10.00

R(k )

Sensitive SCR

Tj = 25 °C

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