LTC4354CDDB LINER [Linear Technology], LTC4354CDDB Datasheet - Page 9

• Manufacturer Part Number: LTC4354CDDB
• Description: Negative Voltage Diode-OR Controller and Monitor
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
The worst case power dissipation in R
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
in D
good solution. The maximum voltage drop across it is:
The maximum power dissipation in the FET is a mere:
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.
∆V = (5A)(23mΩ) = 115mV
P = (5A)(115mV) = 0.6W
P
2
=
Pak package with R
(
72
V
−
12
10 5
k
.
U
V
)
2
=
DS(ON)
U
0 315
.
V
V
A
B
= –5.2V
= –5.2V
W
= 23mΩ (max.) offers a
GND
W
IN
:
DA
1
U
DB
–5.2V Diode-Or Controller
8
Si4466DY
M1
GA
LTC4354
V
4
CC
3
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
place it as close to the V
inputs to the servo amplifiers, DA, DB and V
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.
Si4466DY
GB
M2
6
FAULT
V
SS
2, 5
1µF
C
IN
7
D1
LED
R3
2k
4354 TA02
LOAD
CC
and V
SS
pins as possible. The
LTC4354
SS
pins, should
9
4354f