MIC5156-3.3YN

MIC5156-3.3YN Features

• 4.5mA typical operating current • <1µA typical standby current • Low external parts count • Optional current limit (35mV typical threshold) • 1% initial output voltage tolerance in most configurations • 2% output voltage tolerance over temperature • Fixed output voltages of 3.3V, 5.0V (MIC5156) • Fixed output voltages of 3.3V, 5.0V, 12V (MIC5157) • Programmable (1.3 to 36V) with 2 resistors (MIC5156/8) • Internal charge pump voltage tripler (MIC5157/8) • Enable pin to activate or shutdown the regulator • Internal gate-to-source protective clamp • All versions available in DIP and SOIC

MIC5156-3.3YN General Description

The MIC5156, MIC5157, and MIC5158 Super Low-Dropout(LDO) Regulator Controllers are single IC solutions for high-current low-dropout linear voltage regulation. Super LDO™Regulators have the advantages of an external N-channelpower MOSFET as the linear pass element.The MIC5156/7/8 family features a dropout voltage as lowas the RDS(ON) of the external power MOSFET multiplied bythe output current. The output current can be as high as thelargest MOSFETs can provide.The MIC5156/7/8 family operates from 3V to 36V. TheMIC5156 requires an external gate drive supply to providethe higher voltage needed to drive the gate of the externalMOSFET. The MIC5157 and MIC5158 each have an inter-nal charge pump tripler to produce the gate drive voltage.The tripler is capable of providing enough voltage to drive alogic-level MOSFET to 3.3V output from a 3.5V supply andis clamped to 17.5V above the supply voltage. The triplerrequires three external capacitors.The regulator output is constant-current limited when thecontroller detects 35mV across an optional external senseresistor. An active-low open-collector flag indicates a lowvoltage of 8% or more below nominal output. A shutdown(low) signal to the TTL-compatible enable control reducescontroller supply current to less than 1µA while forcing theoutput voltage to ground.The MIC5156-3.3 and MIC5156-5.0 controllers have inter-nally fixed output voltages. The MIC5156 [adjustable] outputis configured using two external resistors. The MIC5157 is afixed output controller which is externally configured to select

MIC5156-3.3YN Applications

• Ultrahigh current ultralow dropout voltage regulator • Constant high-current source • Low parts count 5.0V to 3.3V computer supply • Low noise/low-dropout SMPS post regulator • High-current, current-limited switch

MIC5156-3.3YN Pin Description MIC5156

Micrel, Inc.Pin Number12345678 (3.3V, 5V)8 (adjustable)Pin NameENFLAGPin FunctionEnable (Input): TTL high enables regulator; TTL low shuts down regulator.Output Flag (Output): Open collector output is active (low) when VOUT is morethan 8% below nominal output. Circuit has 3% hysteresis.GNDVPVDDGDSEACircuit ground.N-channel Gate Drive Supply Voltage: User supplied voltage for driving thegate of the external MOSFET.Supply Voltage (Input): Supply voltage connection. Connect sense resis-tor (RS) to VDD if current limiting used. Connect supply bypass capacitor toground near device.Gate (Output): Drives the gate of the external MOSFET.Drain and Current Limit (Input): Connect to external MOSFET drain and ex-ternal sense resistor (current limit), or connect to VDD and external MOSFETdrain (no current limit).Source (Input): Top of internal resistive divider chain. Connect directly to theload for best load regulation.Error Amplifier (Input): Connect to external resistive divider.