1
dc2027af
DEMO MANUAL DC2027A
Description
LTC4364HDE-1, 2
12V Surge Stopper
with Ideal Diode
Demonstration circuit 2027A showcases the
surge stopper with ideal diode in a 12V, 1A application.
DC inputs of up to 80V and transients to 250V are limited
to just 28.7V at the output. Sagging and reverse-polarity
inputs of up to –24V are isolated from the output by a
reverse-blocking MOSFET configured as an ideal diode.
Further, the output is protected against backfeeding. The
output may be driven –20V to +30V without circuit damage
or backfeeding into the input.
A 4.7μF timer capacitor and robust forward MOSFET
permit the load to operate through ISO-7637-2 load dump
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
performance summary
waveform 5A. Sustained overvoltage or overcurrent condi-
tions cause the LTC4364 to turn off after a timer delay.
The LTC4364-1 (DC2027A-A) latches off and is reset
by pulling
SHDN
low for at least 100μs. The LTC4364-2
(DC2027A-B) automatically retries after a three minute
cool down delay. Start-up and retry are inhibited in the
presence of an input overvoltage.
Design files for this circuit board are available at
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Limits
Operating
DC Survival
1ms Transient
6.6
–24
12
27
80
250
V
V
V
Output Voltage Limits
Regulation Voltage
DC Backfeed Protection
27.2
–20
28.7
30.3
30
V
V
Output Current Capability
Operating
Current Limit
2.125
2.5
1
2.875
A
A
Specifications are at T
A
= 25°C
Quick start proceDure
DANGER! HIGH VOLTAGE TESTING SHOULD BE
PERFORMED BY QUALIFIED PERSONNEL ONLY.
As a safety precaution at least two people
should be present during high voltage testing.
Board Layout
DC2027A is a 2-layer board. There are planes for input,
output and ground; these are replicated on each layer. The
93mil input and output connection turrets are not swaged
and may be removed for attachment of up to 12 AWG wire.
Banana jacks facilitate bench testing. There are exposed
conductors on the bottom of the board, and any banana
plugs present will protrude through the bottom of the
board. The underlying surface should be nonconductive
and clear of any wire, solder and other conductive debris.
The input plane is designed to have at least 78mil (2mm)
clearance to adjacent conductors. This is adequate for
100V
DC
standoff and transients to 250V. Spikes and surges
are withstood by RLED1, QLED1, ROV1, RUV1, R4, Q1 (if
present), D3, M1, RSNUB and CSNUB. These components
are chosen for wide pad spacing, pulse power capability
and voltage stand off, but ultimately limit the maximum
transient input voltage to ≈250V. The time spent above
80V is limited by the pulse power capability of R4.
