2

dc2418af

DEMO MANUAL DC2418A

OPERATING PRINCIPLES

TheLTC4368monitorstheinputvoltageandcurrentsense

resistor voltage. The controller disconnects a load from

the power rail when the input voltage is too low, too high

or negative, or when the voltage across the sense resistor

exceeds 50mV or is less than −3mV for the LTC4368-2

or is less than −50mV for the LTC4368-1. The LTC4368

providesaccurateovervoltageandundervoltagecompara-

tors to ensure that power is applied to the system only if

the input supply is within the allowable voltage window.

Reverse supply protection circuits automatically isolate

the load from negative input voltages.

During normal operation, a high voltage charge pump

enhances the gates of back-to-back external N-channel

power MOSFETs.

The LTC4368 consumes 5µA during shutdown state and

80µA while operating.

The demo board includes the LTC4368 protection con-

troller, two back-to-back connected N-channel MOSFETs,

the resistive divider for UV and OV threshold adjustment,

sense resistor for overcurrent protection, a few LEDs, and

jumpers for visual information and to control signal as-

signment. There is an option for retry operation with two

selectable cool-down time periods or for latch-off after a

forward overcurrent fault.

The DC2418A is available in two versions, DC2418A-A and

DC2418A-B, as shown on the board schematic.

The DC2418A-A is populated with:

• LTC4368-1 having a reverse overcurrent circuit breaker

threshold of –50mV

• SiR870ADP MOSFETs and 5mΩ sense resistor for 10A

maximum load

And the DC2418A-B has:

• LTC4368-2 having a reverse overcurrent circuit breaker

threshold of –3mV

• SiR7942DP dual MOSFET and 20mΩ sense resistor

for 2.5A maximum load

Turrets

GND (E2, E9, E7, E12): Power and control ground.

UV (E3): UV pin.

OV (E4): OV pin.

SHDN (E5): SHDN pin.

FAULT (E8): FAULT pin.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

UV Input Threshold Voltage

UV Falling

492.5

500

507.5

mV

OV Input Threshold Voltage

OV Rising

429.5

500

507.5

mV

Gate Fast Turn-Off Delay

2

6

µs

OV, UV Fault Propagation Delay

1

2

µs

SHDN Input Threshold

SHDN Falling

0.4

0.75

1.2

V

DC2418A-A and DC2418A-B

17.37

17.98

18.61

V

DC2418A-A and DC2418A-B

3.4

3.51

3.63

V

Board Forward Current Trip Threshold

DC2418A-A

DC2418A-B

8.32

2.08

10

2.5

11.72

2.92

A

A

DC2418A-A

DC2418A-B

8.32

0.05

10

0.15

12.12

0.253

A

A