1
dc1555af
DEMO MANUAL DC1555A
DESCRIPTION
LTC4365: High Voltage
UV, OV and Reverse Supply
Protection Controller
Demonstration circuit DC1555A is intended to demonstrate
the performance of the LTC4365 High Voltage Undervoltage
(UV), Overvoltage (OV) and Reverse Supply Protection
Controller.
The LTC4365 protects circuits from input voltages that may
be too high, too low or negative. It operates by controlling
the gates of two back-to-back connected MOSFETs to keep
the output in a safe range. The OV and UV protection levels
are adjusted by resistive dividers at the OV and UV pins.
Asserting the shutdown pin disables the MOSFETs and
places the LTC4365 in a low-current shutdown state. The
FAULT pin is asserted when the Controller is in shutdown
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
(T
A
= 25°C)
mode or when the input voltage is outside of the UV or
OV level.
The LTC4365 can withstand DC voltages between –40V
and 60V and has a valid operating range of 2.5V to 34V.
The DC1555A includes the LTC4365 Controller, two back-
to-back connected power MOSFETs, three jumpers and
three LEDs to indicate the input and output voltages and
the FAULT pin signal.
Design fi les for this circuit board are available at
http://www.linear.com/demo
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Voltage Range
–40
60
V
V
IN(UVLO)
Input Supply Undervoltage Lockout
V
IN
Rising
1.8
2.2
2.4
V
I
VIN
Input Supply Current
SHDN = 0V
SHDN = 2.5V
10
25
50
150
μA
μA
I
VIN(R)
Reverse Input Supply Current
V
IN
= –40V, V
OUT
= 0V
–1.2
–1.8
mA
ΔV
GATE
External N-Channel Gate Drive (Gate – V
OUT
)
V
IN
= V
OUT
= 5V, I
GATE
= –1μA
V
IN
= V
OUT
= 12V to 34V, I
GATE
= –1μA
3
7.4
3.6
8.4
4.2
9.8
V
V
I
GATE(UP)
External N-Channel Gate Pull-Up current
GATE
= V
IN
= V
OUT
= 12V
–12
–20
–30
μA
I
GATE(FAST)
External N-Channel Fast Gate Pull-Down Current
Fast Shutdown, GATE = 20V, V
IN
= V
OUT
= 12V
31
50
72
mA
I
GATE(SLOW)
External N-Channel Gentle Gate Pull-Down Current Gentle Shutdown, GATE = 20V, V
IN
= V
OUT
= 12V
50
90
180
μA
V
UV
UV Input Threshold Voltage
UV Falling, ΔV
GATE(ON)
= 0V
492.5
500
507.5
mV
V
OV
OV Input Threshold Voltage
OV Rising, ΔV
GATE(ON)
= 0V
492.5
500
507.5
mV
t
GATE(FAST)
External N-Channel Fast Gate Turn-Off Delay
CV
FGATE
= 2.2nF
UV: 1V 0.48V or OV: 0.52V to ΔV
GATE
= 0V
2
4
μs
μA
t
FAULT
OV, UV Fault Propagation Delay
UV: 1V 0.48V or OV: 0.52V to FAULT = Low
1
2
μs
V
SHDN
SHDN Input Threshold
SHDN Falling to ΔV
GATE
= 0V
0.4
0.75
1.2
V
