FHT4644L 4-Channel Integrated Adjustable Buck DC/DC Power Module ( 4.0V ~ 15V Input, 0.8V ~ 5.5V Output )

Features

4A continuous full load output current per circuit, up to 5.5A peak

Wide input voltage range: 4.0V to 15V

Output voltage range: 0.8V to 5.5V

Switching Frequency: Typical 1 MHZ, automatically adjustable with input/output

Up to 92% Efficiency

Internal 1mS soft-start

(additional external 1mS optional)

±2% of total output voltage regulation

Over-current protection, over-temperature protection, over-voltage protection, under-voltage protection

Flat and small size:

LGA package(9mm*15mm*1.82mm)

Applications

Multi-rail point-of-load adjustment; CPU and GPU power supply

Power supply for ASIC chips such as CPLDs, DSPs, and FPGAs

Description

The FHT4644L is a non-isolated buck-type integrated molded plastic encapsulated power supply suitable for embedded high-current load points. With its compact size of only 9×15×1.82mm, it can be directly placed next to FPGA/CPU, making it ideal for applications requiring low output voltage and multiple circuits.

Small-sized LGA and BGA packages integrate ICs, inductors, and corresponding components, allowing for the rapid completion of multi-channel power supply system design with only a few external components: a voltage-regulating resistor and a couple of input and output ceramic capacitors. This simplifies system design and maximizes PCB space savings.

Designed based on synchronous rectification Buck topology, it can deliver a maximum of 4A per channel with high power conversion efficiency. It supports voltage conversion from 4.0V to 15V to 0.8V to 5.5V and provides four-channel ON/OFF control and four-channel Power Good signals. Additionally, it features comprehensive protection functions including OCP (Over Current Protection), OVP (Over Voltage Protection), UVP (Under Voltage Protection), OTP (Over Temperature Protection), and SCP (Short Circuit Protection).

The four output channels of the FHT4644L can be used in parallel, and the power modules can also be paralleled among each other.

Typical Applications

Configurable output array

Quad Output Application Circuit

Non-parallel applications                                               Parallel

PIN CONFIGURATION

TOP VIEW

Electrical Characteristics

NOTE : Stresses above the values listed in the "Limit Values" section may cause permanent damage to the device. Prolonged exposure to any of the absolute maximum ratings may affect the reliability and life of the device.

Operation

The FHT4644L is a four-channel independently outputting, non-isolated DC/DC switching voltage regulator. It boasts four individual regulator channels, each capable of delivering up to 4A of continuous output current with minimal external input and output capacitance required. Across an input voltage range of 4.0V to 15V, each voltage regulator channel can provide a precisely adjustable output voltage, ranging from 0.8V to 5.5V, via an external resistor.

RUN Start

Pulling the RUN pin of each voltage regulator channel to ground forces the regulator into a shutdown state, turning off the power MOSFET and most of the internal control circuits. Placing the RUN pin above 0.7V only turns on the internal reference while still keeping the power MOSFET off. Increasing the RUN pin voltage further to above 1.2V will turn on the entire voltage regulator channel.

Output Voltage Setting

Internally in the FHT4644L, the FB pin is connected to the VOUT terminal of each channel through a 100kΩ precision resistor. The output voltage of this module can be controlled by programming the resistance between the FB and GND pins. The calculation is shown below: The reference calculation formula is as follows:

Note: It is recommended to reserve two resistor positions with a precision of 0.5% for fine-tuning the output voltage. The following formula is the calculation formula for the output voltage adjustment resistor:

Table 1 below shows the relationship between the RFB  resistance and each output voltage.

Table 1 RFB  resistor versus each output voltage

Soft Start

The module has a built-in soft-start and an external soft-start pin is available. Connecting a ceramic capacitor of about 3.3nF can increase the delay time.

Input under-voltage protection

Under-voltage lockout when VIN drops below 3.7V.

Note: If the input wires are relatively long, due to the presence of line voltage drop, it is necessary to ensure that the voltage at the input pins of the module is greater than 4.0V to guarantee normal output.

Output over-current protection

When the output current exceeds the current limit value, the FHT4644L enters the protection state. When the output current returns to the normal range, the converter enters the normal operation state.

Power Good

The PGOOD pin is an open-drain pin that can be used to monitor each valid output voltage. When Vout falls below the threshold voltage set for the output voltage, PGOOD goes high. It can also be used to monitor protection functions such as UVLO (Under Voltage Lock Out) and OTP (Over Temperature Protection). By pulling up the resistor to a specific supply voltage, monitoring can be achieved.

The following is a schematic diagram of the PG circuit, and Table 2 presents the PGOOD pin logic table:

Note: VFB is the voltage feedback pin voltage, VTH_PG is the PGOOD threshold voltage, TJ is the junction temperature, and TSD is the temperature during power protection shutdown.

Table 2 PGOOD pin schematic diagram

Over-temperature Protection

When the case temperature of the FHT4644L rises above 135°C, it enters the over-temperature protection state.

Package Description

Soldering and Storage Precautions

For lead-free BGA solder ball products, the peak temperature should not exceed 245℃; 

For leaded BGA solder ball products, the peak temperature should not exceed 225℃.

Recommended reflow soldering profile for reference recommended curves for reference:

Lead Free Processes Leaded Processes

Caution:

1.Due to the large size of the module, please do not place the module under the board for reflow soldering to avoid falling off.

2.For bulk products and those that have been taken out of their original packaging, they should be stored in a desiccator (with a relative humidity of less than 10% inside). For products still in their original packaging, they should also be stored in a desiccator whenever possible.

3.Before mounting on the board, it is necessary to strictly follow the baking conditions to dry the samples: bake at 125°C for more than 48 hours.