LTC4354

9

4354f

–5.2V Diode-Or Controller

LTC4354

LOAD

DB

GA

DA

GB

GND

FAULT

M2

Si4466DY

M1

Si4466DY

4354 TA02

R3

2k

D1

LED

1µF

2, 5

6

14

8

3

7

P

VV

k

W

=

−

=

(.

)

.

72

10 5

12

0 315

2

Choose a 12k 0.5W resistor or use two 5.6k 0.25W

resistors in series.

Next, choose the N-channel MOSFET. The 100V, IRF3710S

good solution. The maximum voltage drop across it is:

∆V = (5A)(23mΩ) = 115mV

The maximum power dissipation in the FET is a mere:

P = (5A)(115mV) = 0.6W

R1 and R2 are chosen to be 2k to protect DA and DB pins

from being damaged by high voltage spikes that can occur

during an input supply fault.

The LED, D1, requires at least 1mA of current to fully turn

on, therefore R3 is set to 33k to accommodate lowest input

supply voltage of –36V.

Layout Considerations

The following advice should be considered when laying

out a printed circuit board for the LTC4354.

The bypass capacitor provides AC current to the device so

be connected directly to the MOSFETs’ terminals using

Kelvin connections for good accuracy.

Keep the traces to the MOSFETs wide and short. The PCB

traces associated with the power path through the MOSFETs

should have low resistance.

APPLICATIO S I FOR ATIO