1

dc2178af

DEMO MANUAL DC2178A

Description

LTC4380

Low Quiescent Current

Surge Stopper

Demonstrationcircuit2178AshowcasestheLTC®4380low

quiescent current surge stopper in an application which

can be configured for 12V, 1A or 24V/28V, 0.5A operation.

The output voltage is clamped by the LTC4380, permitting

theloadtooperateuninterruptedduringtransientsofupto

250V and load dump surges such as ISO-16750-2 Test A.

The output current is limited to 1.25A. In the presence of

a sustained input overvoltage or output overcurrent fault

the LTC4380 shuts off to prevent damage to the N-channel

MOSFET pass element.

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.

operating characteristics

System Voltage

12V

24V/28V

Clamp Select

27V

45V

DC Operating (Full Load)*

9V to 20V

9V to 37.5V

DC Survival

80V

80V

Surge Ride-Through**

ISO-16750-2 Test A

ISO-16750-2 Test A

1ms Transient

250V

250V

Onset of Current Limit

1.25A

1.25A

Short Circuit Current

1.55A

1.55A

1A

0.5A

* Initial production boards are marked with more conservative limits of 19V and 35V. Functionality extends to 4.2V at 25°C. All boards are tested to the

limits shown in the table above.

** Formerly ISO-7637-2 Test Pulse 5A

The output clamp voltage is selected by jumper JP1 to a

value of either 27V or 45V, to suit 12V or 24V/28V sys-

tems. DC2178A-A features the LTC4380-1 which latches

off after a fault, and DC2178A-B features the LTC4380-2

which automatically retries after a cool down delay.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2178A