MIC5159-3.0BM6-TR Datasheet Summary

Overview

The MIC5159 is a precision-voltage regulator controller designed by Micrel, Inc., capable of driving a wide range of output currents with an external P-Channel MOSFET. It is suitable for ultra-high current, ultra-low dropout voltage regulator applications and is particularly useful in high-efficiency linear power supplies, low-voltage distributed power systems, and battery chargers.

Features

• Fast Transient Response
• Input Voltage Range: 1.65V to 5.5V
• Output Voltage Accuracy: ±1.0% initial output tolerance
• Fixed 1.8V or Adjustable Output Voltage down to 1.25V
• Stable with Ceramic Output Capacitor
• Capable up to 10A
• Excellent Line and Load Regulation Specifications
• Logic-Controlled Shutdown
• Programmable Current Limit
• Current-Limit Protection
• IttyBitty® SOT-23-6 Package
• Available Temperature Range: –40°C to +125°C

Applications

• Ultra-high current, ultra-low dropout voltage regulator
• High-efficiency linear power supplies
• Low-voltage distributed power
• Fixed telecom
• Multimedia and PC power supplies
• Battery chargers
• Low-voltage DSP, microprocessor, and microcontroller power supplies

Ordering Information

• Part Number: MIC5159-3.0BM6-TR
• Marking: LZ30
• Voltage: 3.0V
• Junction Temp. Range: -40°C to +125°C
• Package: SOT-23-6

Pin Configuration

The MIC5159 is available in the IttyBitty® SOT-23-6 package. The pin configuration is as follows:

TableCopy

Absolute Maximum Ratings

• Supply Voltage (VIN): +6.0V
• Enable Input Voltage: +6.0V
• Power Dissipation (PD(max)): Note 3
• Storage Temperature (Ts): –65°C to +150°C
• Lead Temperature (soldering, 5sec.): 260°C
• ESD Rating: 2kV

Electrical Characteristics

• Operating Supply Voltage (VIN): +1.65V to +5.5V
• Enable Input Voltage (VEN): 0V to +5.5V
• Junction Temperature (TJ): –40°C ≤ TJ ≤ +125°C
• Package Thermal Resistance (SOT-23-6 θJA): 235°C/W

Typical Characteristics

• Output Voltage Accuracy: ±1.0% at 25°C
• Output Voltage Line Regulation: ±0.1%/V
• Output Voltage Load Regulation: ±1.0%
• Ground Pin Current: 10mA (typical) when enabled
• Adjust Pin Bias Current: 1µA (maximum)
• Maximum VGS (PFET fully ON): 4.5V (VIN = 5.0V), 3.1V (VIN = 3.3V), 2.3V (VIN = 2.5V)
• Current-Limit Threshold: 40mV to 65mV
• Start-up Time: 30µs to 150µs

Functional Diagram

The functional diagram includes a block diagram for both fixed and adjustable output voltage versions, showing the error amplifier, gate buffer, and current sense resistor connections.

Application Information

The MIC5159 is designed to be used with an external P-Channel MOSFET and a small ceramic output capacitor to form a wide variety of ultra-low-dropout voltage regulators. The selection of the P-Channel MOSFET should consider input voltage, gate threshold, load current, dropout voltage, and thermal performance.

Current Sense Resistor Selection

The current sense resistor (RSENSE) is used to set the current limit. It can be calculated using the formula:

RSENSE​=(IOUT(MAX)​50mV​)

For example, for a 5A regulator:

RSENSE​=(5A50mV​)=10mΩ

P-Channel MOSFET Selection

The P-Channel MOSFET must satisfy the following requirements:

• Input voltage
• Gate threshold
• Load current
• Dropout voltage
• Thermal performance
• For example, for a 5A regulator with a 2.5V input and 1.8V output:
• RDS(ON)​=(5A(2.5V−1.8V)​)−10mΩ=130mΩ

Thermal Considerations

The maximum power dissipation of the regulator can be calculated as:

PD​=(VIN​−VOUT​)×IOUT​

For example, for a 2.5V to 1.8V regulator at 5A:

PD​=(2.5V−1.8V)×5A=3.5W

The minimum thermal resistance (θJA) can be calculated as:

ΘJA​=PD​(TJ(MAX)​−TA​)​

For a maximum TJ of 150°C at 60°C ambient temperature:

ΘJA​=3.5W(150∘C−60∘C)​=25.71∘C/W

Short-Circuit Current Limit

The MIC5159 provides a re-entrant current limit to reduce power dissipation during short-circuit conditions. This feature helps protect the MOSFET and improve thermal performance.

Enable/Shutdown

The MIC5159 features an active-high enable pin that allows the regulator to be disabled. Forcing the enable pin low disables the regulator, while forcing it high enables the output voltage.

Output Capacitor

An output capacitor is required to maintain stability and improve transient response. The selection of the capacitor depends on the application and the characteristics of the external MOSFET.

Input Capacitor

An input capacitor of 1.0µF or greater is recommended when the device is more than 4 inches away from the bulk AC supply capacitance or when the supply is a battery.

Layout Considerations

• Place input and output capacitors as close as possible to the respective pins.
• Minimize trace resistance between the current sense and the MOSFET source.
• Maintain a minimum distance between the gate pin and the P-Channel MOSFET gate to avoid high-frequency noise.

Adjustable Regulator Design

The output voltage can be adjusted using two resistors (R1 and R2) connected to the ADJ pin. The resistor values can be calculated using the formula:

R1=R2×((1.235VOUT​​)−1)

For example, for a 1.8V output:

R1=R2×((1.2351.8V​)−1)

Designing with MIC5159

The datasheet provides several application examples with different input/output combinations, maximum currents, and recommended schematics. These examples include various configurations with different P-Channel MOSFETs and output capacitors to meet different power requirements.

Package Information

The MIC5159 is available in the IttyBitty® SOT-23-6 package. Detailed dimensions and tolerances are provided in the datasheet.