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How to use a low voltage current limiter?
An alternative is to use the well-known LM317 voltage regulator as a current limiter. 2 This approach also incurs a voltage drop of ~ 2 V. Another current limiter uses a P-channel MOSFET as a pass device, with gate voltage controlled by a transistor that amplifies the R SENSE voltage drop. 3 This circuit experiences a drop as low as ~0.6 V. 2.
Is there an adjustable shunt regulator for MOSFET?
Adjustable shunt regulator TL431 (IC2) is used here as an error amplifier, and it dynamically adjusts the gate voltage to maintain the regulation at the output. With adequate heatsink for the MOSFET, the circuit can provide up to 3A output at slightly elevated minimum voltage drop.
Is there a limit to the voltage drop?
However, this simple circuit has a limitation due to the associated voltage drop; when activated, there will be a voltage drop at T1 (V CE,SAT) of ~1 V and across R SENSE of ~0.6 V. The total voltage drop is ~1.6 V.
What causes a low voltage MOSFET to go low?
The resultant higher LED current of the MOSFET driver produces an output voltage of ~8 V, which is high enough to drive Q1 well into full conduction. When the load current reaches a value that drives Q2 into conduction, gate-source voltage V GS of Q1 goes low, which forces the load current to go low.
What happens when the load current is low?
When the load current is low, the R SENSE voltage is low, and the low IC1 output remains below the threshold of Q2. The resultant higher LED current of the MOSFET driver produces an output voltage of ~8 V, which is high enough to drive Q1 well into full conduction.
Who are the current efficient, low drop out regulators?
Phillip E. Allen, Chairman Richard Bass J. Alvin Connelly W. Marshall Leach Date Approved by Chairman Current Efficient, Low Voltage, Low Drop-Out Regulatorsiv For the hopes of peaceful coexistence and universal brotherhood ! Current Efficient, Low Voltage, Low Drop-Out Regulatorsv FOREWORD