R3612 데이터 시트보기 (PDF) - Power Innovations
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R3612 Datasheet PDF : 16 Pages
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R3612
PROGRAMMABLE OVERVOLTAGE PROTECTOR
FOR ERICSSON COMPONENTS 3357/3 DCLIC
DECEMBER 1995 - REVISED SEPTEMBER 1997
0
-20
-40
-60
-80
0
400
300
200
100
0
-100
-200
0
5
10
15
Time - ms
IK
IG
IK
5
10
15
Time - ms
20
100
75
50
25
0
-25
-50
20
Figure 6. PROTECTOR HIGH IMPEDANCE POWER CROSS CLAMPING WAVEFORMS
the cathode and anode current decrease, increasing the gate current which peaks for a second time at about
40 mA. The second gate current peak is lower due to the heating caused by the clipping action.
The gate current behaviour is unusual. In the normal common cathode mode operation, once the gate current
reaches its triggering value, IGT, the thyristor switches on. In this case the thyristor is being operated in
common gate mode which results in negative feedback. The negative feedback counteracts the thyristors
internal positive feedback (regeneration) preventing switching until the thyristor does not need a gate current
supplement from the gate supply voltage. In common gate mode, thyristor switches at zero gate current and
the gate current peaks earlier as the thyristor starts to become active.
In Figure 5, although the full cycle average gate current is only 6 mA, peaks of 70 mA and 40 mA occur
during the clamping period. This current is a charging current which tries to make the SLIC supply rail even
more negative. If the current drawn by the SLIC is less than the gate current, the SLIC supply rail may
increase to a point where the SLIC suffers an over voltage on its supply rail. In such cases the shunt
avalanche diode, D6, provides the necessary protection by limiting the maximum supply voltage.
IC protectors
In 1986 an IC version was proposed (A 90 V Switching Regulator and Lightning Protection Chip Set, Robert
K. Chen, Thomas H. Lerch, Johnathan S. Radovsky, D. Alan Spires, IEEE Solid-State Circuits Conference,
February 20, 1986, pp 178/9 and pp 340/1). Commercially, this resulted in the AT&T Microelectronics
LB1201AB device and the higher current Texas Instruments Inc. TCM1060 device, Figure 5.
PRODUCT INFORMATION
11
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