AN302 Datasheet, PDF (6/10 Pages) STMicroelectronics – The purpose of this note is to familiarize

Holding current - the details
AN302
Depending on the production batch, the holding current can vary. However, the dispersion
always remains below the limits specified in the data sheet. For a better perspective, here
are some figures:
● sensitive TRIAC: I_GT (QI): 5 mA (type TW), 2 mA < I_H < 8 mA (specified I_H max: 10 mA)
● standard TRIAC: I_GT (QI): 50 mA (type B), 8 mA < I_H < 40 mA (specified I_H max: 50
mA)
The minimum value of the I_H parameter is not specified in the data sheets.
2.2
2.2.1
2.2.2
Variation of the holding current
Typical variation of I_H with device sensitivity and direction of
commutation
The holding current, I_H, is related to the gate firing current, I_GT as shown in Table 1.
Table 1.
Ratio between I_H+ and I_GT (QI) for sensitive and standard TRIACs
Triac
I_H+ / I_GT (QI)
Sensitive TRIAC 12 Arms (TW type)
2.5 (approx.)
Standard TRIAC 12 Arms (C type)
1.4 (approx.)
Example:
BTA/BTB12-600TW: if I_GT (QI) = 1.5 mA then I_H+ = 3.8 mA.
BTA/BTB12-600C: if I_GT (QI) = 10 mA then I_H+ = 14 mA.
In the case of the TRIAC (as opposed to the thyristor), it is important to note that current I_H-
(electrode A2 negative with respect to A1) can be higher or lower than I_H+ according to the
rated current and the device technology.
Table 2.
Ratio between I_H+ and I_H- for sensitive and standard TRIACs
Triac
I_H+ / I_H-
Sensitive TRIAC 12 Arms (TW type)
0.9 (approx.)
Standard TRIAC 12 Arms (C type)
1.8 (approx.)
Example:
BTA/BTB06-600TW: if I_H+ = 4.3 mA, I_H- = 4.8 mA.
BTA/BTB12-600C: if I_H+ = 15 mA, I_H- = 8.3 mA.
Variation of I_H with junction temperature
The holding current is physically related to the firing current, I_GT. These two parameters vary
with the junction temperature as shown in Figure 7.
Example:
Triac TO-220AB, type BTA/BTB12-600C: I_H = 20 mA at T_j = 25 °C and 14 mA at 110 °C.
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