LT4356CS-3 datasheet(12/24 Pages) LINER

12 / 24 page

LT4356-3

43563f

Fault Timer Current

The timer current starts at around 2μA with 0.5V or less

of VDS, increasing linearly to 50μA with 75V of VDS dur-

ing an overvoltage fault (Figure 1). During an overcurrent

fault, it starts at 4μA with 0.5V or less of VDS but increases

to 260μA with 80V across the MOSFET (Figure 2). This

arrangement allows the pass transistor to turn off faster

during an overcurrent event, since more power is dissipated

during this condition. Refer to the Typical Performance

Characteristics section for the timer current at different

VDS in both overvoltage and overcurrent events.

When the voltage at the TMR pin, VTMR, reaches the 1.25V

threshold, the FLT pin pulls low to indicate the detection

of a fault condition and provide warning to the load of

the impending power loss. In the case of an overvoltage

fault, the timer current then switches to a ﬁxed 5μA. The

interval between FLT asserting low and the MOSFET turn-

ing off is given by:

WARNING =

TMR • 100mV

5μA

APPLICATIONS INFORMATION

Figure 1. Overvoltage Fault Timer Current

Figure 2. Overcurrent Fault Timer Current

tFLT

= 15ms/μF

TOTAL FAULT TIMER = tFLT + tWARNING

tWARNING

= 20ms/μF

tFLT = 93.75ms/μF

tWARNING

= 20ms/μF

VTMR(V)

ITMR = 5μA

VDS = 75V

(ITMR = 50μA)

VDS = 10V

(ITMR = 8μA)

1.35

1.25

TIME

43563 F01

0.50

tFLT

= 2.88ms/μF

TOTAL FAULT TIMER = tFLT + tWARNING

tFLT = 21.43ms/μF

tWARNING

= 2.86ms/μF

tWARNING

= 0.38ms/μF

VTMR(V)

VDS = 10V

(ITMR = 35μA)

1.35

1.25

0.50

TIME

43563 F02

VDS = 80V

(ITMR = 260μA)

LT4356CS-3 bảng dữ liệu(PDF) 12 Page - Linear Technology

LT4356CS-3 bảng dữ liệu(HTML) 12 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

bảng dữ liệu tải về

Link URL