Current-Limit Circuit for the Buck Regulator

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Additional Information:

A current limit can be added to a step-down converter by using a MAX4173H current-sense amplifier to inject current into the feedback network. D1 sharpens the threshold of current limit by converting the current sense feedback signal from linear to exponential. This current-limit circuit can be scaled for any output current by adjusting R3. In this case, the MAX1692 provides up to 600mA output and the MAX4173H limits the output current by decreasing the output voltage for output current above 300mA.

IL (mA) VOUT (V)
0 3.827
100 3.729
200 3.701
258 3.637 (-5%)
300 3.503
312 3.444 (-10%)
347 3.254 (-15%)
380 3.062 (-20%)
400 2.951
414 2.862 (-25%)
450 2.630
500 2.305
550 1.977
600 1.732


Designed, Built, Tested

Board pictured here has been fully assembled and tested. Not available for sale.


Maxim Devices (1)

Part Number Name Product Family Order Design kits and evaluation modules
MAX1692 Low-Noise, 5.5V Input, PWM Step-Down Regulator Switching Regulator - Switching Regulators Buy Now Design Kits

Maxim Devices (1)

Part Number Product Family
Switching Regulator - Switching Regulators
Low-Noise, 5.5V Input, PWM Step-Down Regulator

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