12V, 4.5A Step-Down Voltage Regulator D36V50F12 Pololu

DESCRIPTION

This powerful synchronous switching step-down (or buck) regulator takes an input voltage of up to 50V and efficiently reduces it to 12V. The board measures only 1″x1″ yet delivers typical maximum continuous output currents between 2.3A and 6.5A, depending on the input voltage, which makes it well suited for powering moderate to large loads. An optional enable input with a precise cutoff threshold can be used to put the regulator in a low-power state with a current draw of10µA to 20µA per volt on VIN. The regulator also features reverse voltage protection and a power-good output that indicates when the regulator cannot adequately maintain the output voltage.

This regulator has six connections, some of which are duplicated on multiple pins: power good (PG), enable (EN), input voltage (VIN), input voltage after reverse protection (VRP), output voltage (VOUT), and ground (GND). The “power good” indicator, PG, is an open-drain output that goes low when the regulator’s output voltage either rises more than 20% above or falls more than 10% below the nominal voltage (with hysteresis). An external pull-up resistor is required to use this pin.

The regulator, which is enabled by default, can be put into a low-power sleep state by reducing the voltage on the EN pin below 1.2V, and it can be brought out of this state again by increasing the voltage on EN past 1.35V. The quiescent current draw in this sleep mode is dominated by the current in the 100kΩ pull-up resistor from ENABLE to VIN and in the reverse-voltage protection circuit, which altogether will be between 10µA and 20µA per volt on VIN. The tight tolerance of the enable input allows a precise low-VIN cutoff to be set, such as with the output of an external voltage divider powered by VIN, which is useful for battery-powered applications where draining the battery below a particular voltage threshold could permanently damage it.

The input voltage, VIN, powers the regulator. Voltages between 4.5V and 50V can be applied to VIN, but generally, the effective lower limit of VIN is VOUT plus the regulator’s dropout voltage, which varies approximately linearly with the load (see below for graphs of the dropout voltage as a function of the load). VRP provides access to the input voltage after reverse-voltage protection; this can be used as an output to power other devices, or the input voltage can be connected to VRP instead of VIN to bypass the reverse protection. VOUT is the regulated output voltage.

All of the connections are arranged on a 0.1″ grid for compatibility with solderless breadboards, connectors, and other prototyping arrangements that use a 0.1″ grid. The PG connection is the only one not accessible along the edge of the board. A 1×12 straight male header strip is included with the regulator. Each header pin is only rated for 3A (6A combined per pair), and solderless breadboards are usually not intended to handle more than a few amps, so for higher-power applications, thick wires should be soldered directly to the board.

The power connections (VIN, VRP, VOUT, and GND) are duplicated across both rows of through-holes, allowing two header pins to be used for each connection. Note that the EN and PG pins are not duplicated and are adjacent on different rows, so if you intend to use the regulator on a breadboard, be careful to avoid installing header pins in a way that shorts EN to PG.

FEATURES

• Input voltage: 13.3V to 50V
• Output voltage: 12V with 4% accuracy
• Typical maximum continuous output current: 2.3A to 6.5A
• Typical efficiency of 90% to 95%, depending on input voltage, output voltage, and load
• Switching frequency: ~500kHz under heavy loads
• Power-save mode with an ultrasonic operation that increases light load efficiency by reducing switching frequency, but keeps it above the audible range (20kHz)
• 2mA to 4mA typical no-load quiescent current
• Enable input with a precise cutoff threshold for disconnecting the load and putting the regulator into a low-power state that draws approximately 10µA to 20µA per volt on VIN
• “Power good” output indicates when the regulator cannot adequately maintain the output voltage
• Output Undervoltage and overvoltage protection
• Soft-start feature limits inrush current and gradually ramps output voltage
• Integrated reverse-voltage protection up to 40V, over-current and short-circuit protection, over-temperature shutoff
• Compact size: 1″ x 1″ x 0.375″ (25.4mm x 25.4mm x 9.5mm)
• Three 0.086″ mounting holes for #2 or M2 screws

General specifications

• Dimensions: Size 1″ x 1″ x 0.375″¹ Weight 7.0 g¹
• Minimum operating voltage: 13.3V²
• Maximum operating voltage: 50V
• Continuous output current: 4.5A³
• Output voltage: 12V
• Reverse voltage protection?: Y⁴
• Maximum quiescent current: 4mA⁵
• Output type: fixed 12V

1. Without including optional headers.
2. Subject to dropout voltage considerations.
3. Typical continuous output current at 36V in. Actual achievable continuous output current is a function of input voltage and is limited by thermal dissipation.
4. To -40V. Connecting supplies over 40V in reverse can damage the device.
5. While enabled with no load. Can be reduced to under 1mA using the enable pin.

Identifying markings

• PCB dev codes: reg24d
• Other PCB markings: 0J12574, blank white box

RESOURCES

• Dimension diagram of the D36V50Fx Step-Down Voltage Regulator (312k pdf)
• 3D model of the D36V50Fx Step-Down Voltage Regulator (5MB step)
• Drill guide for the Pololu D36V50Fx family of step-down voltage regulators (52k dxf)