1
dc1555cfd
DEMO MANUAL DC1555C
Description
LTC4365/LTC4365-1:
Overvoltage, Undervoltage and
Reverse Supply Protection Controller
Demonstration circuit DC1555C is intended to demon-
strate the performance of the LTC4365 and LTC4365-1
Undervoltage, Overvoltage and Reverse Supply Protection
Controllers.
The
protect circuits from input volt-
ages 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
SHDN
pin disables the
MOSFETs and places the controller in a low-current shut-
down state. The
FAULT
pin is asserted when the Controller
is in shutdown mode or when the input voltage is outside
of the UV or OV level.
The LTC4365 and LTC4365-1 can withstand DC voltages
between –40V and +60V and have a valid operating range
of 2.5V to 34V.
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)
Regarding the supply protection parameters, the LTC4365
and LTC4365-1 are identical. The only differences are
in the gate fault recovery delay time and the delay from
turn-off to low-power operation. These delays are 36ms
(typ, both) for the LTC4365, while they are 1ms and 0.7ms
respectively for the LTC4365-1.
The DC1555C includes the 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 files for this circuit board are available at
http://www.linear.com/demo/DC1555C
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VIN
Board Input Voltage Range
–30
30
V
V
IN(UVLO)
Input Supply Undervoltage Lockout
VIN 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
VIN = –40V, V
OUT
= 0V
–1.2
–1.8
mA
ΔV
GATE
External N-Channel Gate Drive (GATE – VOUT)
VIN = VOUT = 5V, I
GATE
= –1µA
VIN = VOUT = 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 = VIN = VOUT = 12V
–12
–20
–30
µA
I
GATE(FAST)
External N-Channel Fast Gate Pull-Down Current
Fast Shutdown, GATE = 20V, VIN = VOUT = 12V
31
50
72
mA
I
GATE(SLOW)
External N-Channel Gentle Gate Pull-Down Current Gentle Shutdown, GATE = 20V, VIN = VOUT = 12V
50
90
150
µA
V
UV
UV Input Threshold Voltage
UV Falling
→
ΔV
GATE
= 0V
492.5
500
507.5
mV
V
OV
OV Input Threshold Voltage
OV Rising
→
ΔV
GATE
= 0V
492.5
500
507.5
mV
t
GATE(FAST)
External N-Channel Fast Gate Turn-Off Delay
C
GATE
= 2.2nF, UV or OV Fault
2
4
µs
t
FAULT
OV, UV Fault Propagation Delay
Overdrive = 50mV, VIN = VOUT = 12V
1
2
µs
V
SHDN
SHDN
Input Threshold
SHDN
Falling to ΔV
GATE
= 0V
0.4
0.75
1.2
V
