DEMO MANUAL DC1555C
LTC4365/LTC4365-1:
Overvoltage, Undervoltage and
Reverse Supply Protection Controller
Description
Demonstration circuit DC1555C is intended to demon-
strate the performance of the LTC4365 and LTC4365-1
Undervoltage, Overvoltage and Reverse Supply Protection
Controllers.
The
LTC
®
4365/LTC4365-1
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.
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
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
SYMBOL
VIN
V
IN(UVLO)
I
VIN
I
VIN(R)
ΔV
GATE
I
GATE(UP)
I
GATE(FAST)
V
UV
V
OV
t
GATE(FAST)
t
FAULT
V
SHDN
PARAMETER
Board Input Voltage Range
Input Supply Undervoltage Lockout
Input Supply Current
Reverse Input Supply Current
External N-Channel Gate Drive (GATE – VOUT)
External N-Channel Gate Pull-Up current
(T
A
= 25°C)
CONDITIONS
VIN Rising
SHDN
= 0V
SHDN
= 2.5V
VIN = –40V, V
OUT
= 0V
VIN = VOUT = 5V, I
GATE
= –1µA
VIN = VOUT = 12V to 34V, I
GATE
= –1µA
GATE = VIN = VOUT = 12V
Fast Shutdown, GATE = 20V, VIN = VOUT = 12V
UV Falling
→
ΔV
GATE
= 0V
OV Rising
→
ΔV
GATE
= 0V
C
GATE
= 2.2nF, UV or OV Fault
Overdrive = 50mV, VIN = VOUT = 12V
SHDN
Falling to ΔV
GATE
= 0V
0.4
3
7.4
–12
31
50
492.5
492.5
MIN
–30
1.8
2.2
10
25
–1.2
3.6
8.4
–20
50
90
500
500
2
1
0.75
TYP
MAX
30
2.4
50
150
–1.8
4.2
9.8
–30
72
150
507.5
507.5
4
2
1.2
UNITS
V
V
µA
µA
mA
V
V
µA
mA
µA
mV
mV
µs
µs
V
External N-Channel Fast Gate Pull-Down Current
UV Input Threshold Voltage
OV Input Threshold Voltage
External N-Channel Fast Gate Turn-Off Delay
OV, UV Fault Propagation Delay
SHDN
Input Threshold
I
GATE(SLOW)
External N-Channel Gentle Gate Pull-Down Current Gentle Shutdown, GATE = 20V, VIN = VOUT = 12V
dc1555cfd
1
DEMO MANUAL DC1555C
operating principles
The LTC4365/LTC4365-1 monitors the input rail voltage
and disconnects downstream circuits when the input volt-
age is too low, too high or negative. The LTC4365 provides
accurate overvoltage and undervoltage comparators to
ensure that power is applied to the system only if the input
supply is within the allowable voltage window. Reverse
supply protection circuit automatically isolates the load
from negative input voltages.
During normal operation, a high voltage charge pump
enhances the gate of external N-channel power MOSFETs.
The controller consumes 10µA during shutdown and
125µA while operating.
2
dc1555cfd
DEMO MANUAL DC1555C
Quick start proceDure
Demonstration circuit 1555C is easy to set up to evaluate
the performance of the LTC4365/LTC4365-1. Refer to
Figures 1a and 1b for proper measurement equipment
setup and follow the procedure below.
Note that the circuit on the DC1555C is optimized for 12V
operation. The Si4214 FET limits overvoltage and reverse
voltage to 30V and –30V, respectively. Refer to the LTC4365
data sheet for applications optimized for other voltages.
Reverse Voltage Test (Figure 1b)
1) Set JP1 to EN.
2) Set JP2 and JP3 to CONNECT LED.
3) Connect a power supply across VIN and GND in a
negative configuration (connect positive rail to GND
and negative rail to VIN).
4) Connect voltmeters at the input and output and am-
meter in series with supply.
5) Ramp VIN down to –30V (referenced to GND).
6) Verify that the output voltage is between 0V and –0.5V,
all LEDs are off, and the input current is <1.8mA. (FET
leakage or other board leakage paths can pull VOUT
slightly negative, but it will be clamped by the internal
protection diode.)
7) Ramp supply back to 0V.
Undervoltage/Overvoltage Test (Figure 1a)
8) Reverse the polarity of power supply connection across
VIN to GND (connect positive rail to VIN and negative
rail to GND).
9) Ramp supply up to 30V and verify green VIN LED, red
FAULT
LED, green VOUT LED, and VOUT according to
Table 1 within the various voltage ranges.
10) Ramp supply down from 30V down to 0V and verify
green VIN LED, red
FAULT
LED, green VOUT LED, and
VOUT according to Table 1.
Table 1
VIN
0V to 5.77V
6.56V to 13.51V
15.47V to 30V
VOUT
= 0V
= V
IN
= 0V
VIN LED
Off/Dim/On
On
On
VOUT LED
Off
On
Off
FAULT
LED
On
Off
On
Jumper Test
11) Remove load and set supply to 9V.
12) Move jumpers and verify LEDs according to Table 2.
Table 2
JP1
EN
DIS
EN
JP2/JP3
CONNECT LED
CONNECT LED
Open
VIN LED
On
On
Off
VOUT LED
On
Off
Off
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DEMO MANUAL DC1555C
Quick start proceDure
Figure 1a. Undervoltage/Overvoltage Measurement
Figure 1b. Reverse Voltage Measurement
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dc1555cfd
5
4
2
1
3
REVISION HISTORY
C3
(OPT)
ECO
-
Apr 15, 2015
Oct 26, 2015
REV
DESCRIPTION
Replaced LED's, Added -B Assembly
Vlad Ostrerov
APPROVED
DATE
Vlad Ostrerov
1000pF
0805
D5
BZT52C15T
(OPT)
Q2A
2N7002VC-7-F
(OPT)
Q2B
2N7002VC-7-F
(OPT)
D
1
2
Replaced Q1, LED's & CLD's.
D
*
VOUT
D1
S1
S2
D2
VIN
(LOW CURRENT MOSFET, SMALL PACKAGE OPTION)
G1
G2
-30 TO 0V
0V TO 6V
REVERSE PROTECTED
UV PROTECTED
6V TO 15V
Q1A
Si4214DDY-T1-GE3
VOUT
C1
4.7µF
50V
(OPT)
C2
47µF
+
35V
(OPT)
Q1B
Si4214DDY-T1-GE3
E6
schematic Diagram
15V TO 30V
(UV = 6V)
(OV = 15V)
GATE ON
OV PROTECTED
E1
C
*
R4
510k
R1
1M
1%
VIN
VIN
VOUT
E7
GND
C
*
E2
GND
D6
DFLT20A
(OPT)
U1
1
VIN
GATE
D7
DFLT40A
(OPT)
8
7
6
5
E8
FAULT
2
UV
VOUT
E3
UV
R2
54.9k
1%
E4
R3
36.5k
1%
3
OV
FAULT
OV
4
GND
SHDN
EN
SHDN
1
LTC4365CTS8
B
2
B
DIS
3
JP1
SHDN
E5
BOARD ASSEMBLY
VIN
VOUT
CONNECT
LED
D4
LED DRIVE
1
2
3
JP3
CLD3
CMJ2000 TR
CLD2
CMJ2000 TR
1
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1N4148WT
OPEN
JP2
2
DC1555C-A
DC1555C-B
U1
LTC4365CTS8
LTC4365CTS8-1
3
CLD1
CMJ2000 TR
CUSTOMER NOTICE
APPROVALS
RB
Vlad O.
A
TECHNOLOGY
TITLE: SCHEMATIC
1630 McCarthy Blvd.
Milpitas, CA 95035
www.linear.com
Phone: (408)432-1900
Fax: (408)434-0507
LTC CONFIDENTIAL - FOR CUSTOMER USE ONLY
A
D1
GRN
VIN
D3
RED
FAULT
D2
GRN
VOUT
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
APP ENG.
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
SIZE
N/A
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
3
MODIFY DATE:
Oct 26, 2015
2
HIGH VOLTAGE NFET DRIVER UV, OV AND
REVERSE SUPPLY PROTECTION
IC NO.
REV.
LTC4365CTS8/LTC4365CTS8-1
2
DEMO CIRCUIT 1555C
SHEET
1
1
OF
1
5
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DEMO MANUAL DC1555C
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