FHT4644H 4 Channel Integrated DC/DC Adjustable Buck Power Module ( 4.0V ~ 14V Input, 0.6V ~ 5.5V Output )

Features

4A continuous full load output current per circuit

Wide input voltage range: 4.0V to 14V

Output voltage range: 0.6V to 5.5V

Switching frequency: Typical 1 MHZ

High efficiency: 92%

Internal 1mS soft start (additional external 1mS optional)

±1.5% total output voltage regulation

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

Regular size: 

LGA package (9mm*15mm*4.32mm) 

BGA package (9mm*15mm*5.01mm)

Ultra-thin size: less than half the thickness of regular size

LGA package(9mm*15mm*2.82mm)

BGA package(9mm*15mm*3.42mm)

Applications

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

Power supply for ASIC chips 

Description

The FHT4644H is a non-isolated step-down all-in-one molded point power supply for embedded high-current load points. Its size is only 9 x 15 x 2.42mm and can be placed directly next to the FPGA/CPU, making it ideal for low output voltage, multi-application applications.

The small size of the LGA and BGA package integrated IC, inductors and the corresponding components, only need to configure a peripheral voltage regulator resistor, a few input and output ceramic capacitors, you can quickly complete the design of the multi-channel power supply system to simplify the design of the system, maximize the savings of PCB space.

Based on synchronous rectification Buck topology, maximum 4A per circuit, high power conversion efficiency, can be converted from 4.0V to 14V.

0.6~5.5V, provide four-way ON/OFF control, four-way Power Good, OCP (over-current), OVP (over-voltage), UVP (under-voltage), OTP (over-temperature), SCP (short-circuit) protection.

Typical Application

Configurable output array

Quad Output Application Circuit

Non-parallel applications                                    Parallel 

PIN CONFIGURATION

77-Pins (16mm x 9mm x 5.01mm) 

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 FHT4644H is a quad independent output non-isolated DC/DC switching regulator. It has four independent regulator channels, each capable of delivering up to 4A of continuous output current with minimal external input and output capacitance. Each regulator channel provides a precisely regulated output voltage over the 4.0V to 14V input voltage range of 0.6V to 5.5V through an external resistor.

RUN Start

Pulling the RUN pin of each regulator channel to ground forces the regulator into a shutdown state, turning off the power MOSFETs and most of the internal control circuitry. Placing the RUN pin above 0.7V only turns on the internal reference while still keeping the power MOSFETs off. Further increasing the RUN pin voltage above 1.2V will open the entire regulator channel.

Output Voltage Setting

Inside the FHT4644H, the FB pin is connected to the VOUT terminal of each channel through a 60.4kΩ precision resistor. The output voltage of this module can be controlled by programming the resistance between the FB and GND pins. The calculation is as follows: Please refer to the formula below for the calculation:

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

Switching Frequency Selection

The operating frequency of the FHT4644H has been optimized to achieve a compact package size and minimal output ripple voltage, while still maintaining high efficiency. The default operating frequency is internally set to 1MHz. In most applications, no additional frequency adjustment is required. If any operating frequency other than 1MHz is needed based on the application, it can be externally synchronized with a clock ranging from 700kHz to 1.3MHz.

Discontinuous conduction mode (DCM) setting

In applications requiring intermediate current for low output ripple and high efficiency, the discontinuous conduction mode (DCM) should be utilized by connecting the mode pin to SGND. Under light load conditions, the internal current comparator may remain tripped for several cycles, forcing the top MOSFET to remain off for those cycles, thereby skipping cycles. In this mode, the inductor current does not reverse.

Forced Continuous Conduction Mode (CCM)

In applications where fixed-frequency operation is more prevalent and certain operations are more critical than low-current efficiency, such as when low output ripple is required, the forced continuous conduction mode (CCM) should be used for operation. This can be enabled by connecting the MODE pin to INTVCC. In this mode, the inductor current is allowed to flow continuously, with the COMP voltage controlling the current comparator threshold throughout, ensuring that the top MOSFET turns on with each oscillating pulse even at low output loads. During startup, the forced continuous mode may be disabled to prevent the inductor from causing electrical issues, but once operational, CCM ensures stable and continuous current flow.

Soft Start

The module has a built-in soft-start, and an external soft-start pin is available to increase the delay time by connecting a ceramic capacitor of about 33 to 100nF.

Input under-voltage protection

Under-voltage lockout when VIN drops below 3.7V.

Note: If the input line is long, due to the line voltage drop, it is necessary to ensure that the voltage to the input pin of the module is greater than 4.0V to ensure normal output.

Output overcurrent protection

When the output current exceeds the current limit value, the FHT4644H enters the protection state. When the output current returns to the normal range, the converter enters the normal operating state.

Power Good

The PGOOD pin is an open drain pin that can be used to monitor each active output voltage. PG goes high when Vout falls below the set output voltage threshold. It can also be used to monitor protection functions such as UVLO and OTP, which can be monitored by pulling the resistor up to a specific supply voltage.

Over-temperature protection

When the case temperature of the FHT4644H 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.