FHT4644F 4-Channel DC/DC Magnetically Integrated Buck Power Module (SiP) | 4.5V to 16V Input, 0.6V to 5.5V Output

Features

Adopting SMT process, SIP plastic encapsulated packaging

General specification： GJB 10164-2021

Output current: 4A continuous full-load output current per channel, peak at 5.5A

Operating temperature (Tc) ：-55℃ ~ +125℃

Wide input voltage range：4.5V to 16V

Output voltage range：0.6V to 5.5V

Switching frequency: Select-able at 800KHZ or 1.2MHZ (factory setting)

Operating mode: adjustable between PFM and FCCM

Efficiency： 92%

No-load power consumption: total of 0.01W for 4 channels (12Vin, 5V output)

Output ripple voltage： 15mVp-p（typical）

Voltage regulation rate： ±1.0% （typical）

Load regulation rate： ±0.5% （typical）

Soft start: internal 1mS soft start

Protection: output over-current, overheat, output over-voltage, input under-voltage

Standard dimensions:

LGA package (9.0*15.0*4.32mm)

LGA package (9.0*15.0*5.01mm)

Ultra-thin Dimensions:

LGA package(9.0*15.0*1.82mm) 

LGA package (9.0*15.0*2.42mm)

Applications

Multi-rail load point regulation;

Power supply for CPUs and GPUs；

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

Description

The FHT4644F is a non-isolated buck DC/DC power module with a wide input voltage range of 4 to 16V and an adjustable output range of 0.6 to 5.5V. It features four output channels, each capable of delivering up to 4A. Users can choose between LGA and BGA packaging options.

The FHT4644F is an SMT surface-mount module that is welded onto the PCB board using reflow soldering. It is characterized by high power density and a small size, with an ultra-thin thickness of only 1.82mm and a power density reaching 300W/cm³. The power module circuit integrates power chips, inductors, and related components. Each output only requires a voltage-regulating resistor and a few input and output ceramic capacitors on the periphery to quickly complete the design of a multi-channel power supply system. This simplified system design maximizes space savings on the PCB layout.

The FHT4644F, serving as a point-of-load power supply, can be directly mounted next to the FPGA to provide high-precision voltages such as 5.0V, 3.3V, 2.5V, and 1.2V for the digital circuits, FPGA control circuits, motherboard, CPU, communication modules, storage, and other components in the system. Each channel can continuously deliver a current of 4A. It is ideally suited for applications requiring low output voltages and multiple channels.

The FHT4644F has three adjustable operating modes: PFM, UFM, and FCCM. The operating frequency is 800KHZ and 1.2MHZ, which can be selected and set at the factory.

All components of FHT4644F are made in China, and can provide independent and controllable reports. In addition, the power module also has the characteristics of high reliability, high efficiency and long life. Especially in low-voltage output, its efficiency is significantly higher than that of similar products, which can provide more reliable and stable power supply for the system.

Typical Applications

Circuit Application Diagram

Pin Configuration

TOP VIEW

Pin Configuration

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 FHT4644F is a four-channel, independently outputting, non-isolated DC/DC switching voltage regulator. It boasts four separate regulator channels, each capable of delivering up to 4A of continuous output current, requiring only minimal external input and output capacitors. Across an input voltage range of 4.5V to 16V, each regulator channel can provide a precisely adjustable output voltage, ranging from 0.6V to 5.5V, via an external resistor.

RUN Enable

Pulling the RUN pin of each regulator channel to ground forces the regulator into a shutdown state, turning off the power MOSFET and most internal control circuits. Placing the RUN pin above 0.7V only turns on the internal reference while still keeping the power MOSFET off. Further increasing the voltage on the RUN pin to above 1.3V will turn on the entire regulator channel.

Output Voltage Setting

Within the FHT4644F, 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 shown below:

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 used to calculate the output voltage adjustment resistor:

Table 1: Relationship Between RFB Resistance and Various Output Voltages

Soft-Start Feature

The module is equipped with a built-in 1.0 millisecond (mS) soft-start function.

Working Mode Adjustment (MODE)

There are two mode options: PFM and FCCM. By connecting the MODE pin to VCC, the device operates in the Forced Continuous Conduction Mode (FCCM). By grounding the pin, the device will run in Pulse Frequency Modulation (PFM) mode.

Units are in mS. For example, when the additional soft-start time is 1ms, the required soft-start capacitor is 4nF.

Input Under-Voltage Protection

When VIN drops below 3.7V, under-voltage lockout (UVLO) occurs.

Note: If the input cable is relatively long, due to the voltage drop across the cable, it is necessary to ensure that the voltage at the input pins of the module is greater than 4.5V to guarantee normal output. This is to compensate for the voltage loss in the cable and ensure that the module receives sufficient input voltage to operate correctly.

Output Over-Current Protection

If the output current goes above the limit, the FHT4644F protects itself by entering a safe mode.When the output current returns to a safe level, the converter starts working normally again.

Power Good

The PGOOD pin is an open-drain output that indicates the status of the output voltage. If the output voltage drops below a certain threshold, the PGOOD pin signals this by going high. This pin can also be used to detect when protective features like UVLO or OTP are activated. By attaching a resistor, you can pull the PGOOD pin up to a specific voltage level for monitoring purposes.

Below is a schematic diagram of the PG (Power Good) circuit, followed by List 2 which presents the logic table for the PGOOD pin:

Notes: VFB represents the voltage at the voltage feedback pin, VTH_PG is the threshold voltage for the PGOOD pin, TJ stands for junction temperature, and TSD refers to the temperature at which the power supply protection shutdown occurs.

Package Description

Operating Conditions, Testing and Special Application Notes

1、Recommended Operating Conditions for This Module：

★Input Voltage Range：VIN = 4.5V～16V

★Output Voltage Range：VOUT = 0.8V～5.0V      

★ Output Current Range：It is recommended to use with a 80% derating）

Iout= 0～4A Independent operation of a single channel 

★Operating Case TemperatureTC： -55℃ ~ 125℃

2、Testing and Application Instructions

It is not recommended to use a linear power supply for functional testing of this power module (as linear power supplies tend to generate transient voltage fluctuations when adjusting the output, posing a risk of exceeding the maximum rated voltage). Instead, it is recommended to use a switching power supply or a DC/DC module power supply.

★ This power module features a high power density circuit, and it is recommended to use a PCB board with 4 layers or more for layout. Considering long-term stable operation under high temperature conditions, it is advisable to implement appropriate load derating (80% of rated load) or thermal management measures (options include: system-level air cooling, attaching a heatsink above the power module, increasing the copper-clad area on the PCB board beneath the power module, etc.).

★ For the PCB board application of this power module, it is recommended to use wider copper foil for the layout of VIN, VOUT, and GND to reduce conduction losses and thermal stress caused by high currents. It is advisable to place the input and output filtering capacitors close to the power module. To avoid interference, it is recommended to layout the input capacitors and output capacitors with a distance greater than 1 cm between them.

★ If you were previously using an LTM4644 peripheral circuit design, you will need to recalculate RFB according to the following formula.，Only the resistance value needs to be changed, and there is no need to modify the PCB layout.

★ This power module is a hermetically sealed product. Before soldering, check the changes on the humidity indicator card to determine if pre-baking treatment is necessary.

★Attention should be paid to electrostatic protection during product transportation.

Precautions for Reflow Soldering

1. Products that are well-packaged must undergo baking at 125°C for 24 hours before use. If the packaging bag is found to be torn or if the desiccant or indicator label has changed color, the products must undergo baking at 125°C for 48 hours before use. For more information, please refer to the IPC/JEDEC J-STD-033 standard.

2.For reflow soldering of lead-free BGA solder ball products, the peak temperature should not exceed 245°C; for lead-containing BGA solder ball products, the peak temperature should not exceed 225°C.

3.It is recommended to use a stencil thickness of 125um-160um, with stencil openings slightly smaller than the solder pads. Taking a Φ0.635mm solder pad as an example, the recommended stencil opening size is Φ0.620mm.

4. The solder paste can be either lead-free SAC or SnPb (with lead). Powder types 3 or 4 are recommended. Different brands of solder paste may have different welding recommendations, so please pay attention to the references. The porosity rate is recommended to not exceed 25%.

Recommended Reflow Soldering Parameters Table

Recommended Reflow Soldering Profile (for reference)

Reflow soldering profile for SnPb solder paste

Reflow soldering profile for lead-free solder paste