FHT4623 DC/DC Adjustable Buck Converter Power Module ( 4.2V-20V Input, 0.6V-5.5V Output )

Features

3A output current

Wide input voltage range: 4.2V-20V

Output voltage: 0.6V-5.5V

Switching frequency: 800kHz

Efficiency up to 95%

Soft start

Small size, surface mount package:

LGA (6.75mm x 6.75mm x 2.95mm)

Applications

PCIe boards, back-powered boards

Telecommunications, Data Communications, Networking, and Industrial Equipment

Card-type and rack-mounted data storage devices

Description

The FHT4623 is an integrated DC/DC buck converter with a 3A output.

It internally integrates components such as chips, inductors, resistors, capacitors, and other elements.

The input voltage range of the FHT4623 is from 4.2V to 20V, and the output voltage range is from 0.6V to 5.5V, with a switching frequency of 800kHz. Only a small number of input and output filter capacitors are required for external configuration to use it.

This product is small in size and can be mounted on space-constrained PCB boards to power load points with high-density installations.

The FHT4623 is encapsulated in a heat-dissipating, compact, and small molded package using an LGA package with dimensions of 6.75mm×6.75mm×2.95mm, suitable for SMT automatic placement.

Typical Applications 

5V/3A Buck Converter Module                                          Efficiency @Vout=5V

Pin Configuration

Electrical Characteristics

Note 1: 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.

Note 2: The maximum continuous output current may be derated due to the FHT4623 junction temperature.

Note 3: The performance specifications of the FHT4623 are guaranteed over the full -40°C to 125°C internal operating stability range. Note that the maximum internal temperature is determined by specific operating conditions in conjunction with the board layout, the rated thermal resistance of the package, and other environmental factors.

Operation

The FHT4623 is a self-contained, non-isolated, step-down switching DC/DC power supply module with an input range of 4.2V to 20V, capable of delivering up to 3A of output current. The module offers high conversion efficiency and a precisely adjustable output voltage from 0.6V to 5.5V. Since the FHT4623 is a step-down converter, make sure the input voltage is high enough to support the required output voltage and load current.

Selection of Input Capacitance

Input capacitors of 10μF/35V/X5R and above are recommended. Ceramic capacitors have the characteristics of small size, high reliability, very low ESR, etc. X5R, X7R type ceramic capacitors can maintain stable performance in a wide range of temperature and voltage, which can effectively reduce the input voltage ripple.

Selection of Output Capacitance

The recommended output capacitor is a 47μF/6.3V/X5R or higher ceramic capacitor. It is recommended that multiple capacitors be connected in parallel with a total capacitance of 47μF or more. Parallel connection of multiple ceramic capacitors can reduce the equivalent ESR and ESL, thus effectively reducing the output voltage ripple.

Output Voltage Setting

The output voltage of the module can be set by the external GND resistor RFB on the FB pin, and the reference formula is as follows:

Note: It is recommended that two resistor positions be reserved for precise adjustment of the output voltage.

The resistance value of RFB  is adjusted according to the customer's requirements, where RFB is in kΩ.

PFM model

During light load, the FHT4623 operates in PFM mode, and the switching frequency decreases as the load current decreases in order to improve the efficiency during light load.

This reduces switching losses. When the load is increased, the switching frequency is increased and the ripple is reduced.

Over-current protection

When the output current is greater than 6A, the module triggers hiccup overcurrent protection

Input Under-Voltage Protection

Input undervoltage protection is triggered and locked when the input voltage drops below 3.9V; the module starts when the input voltage rises above 4.2V and the RUN pin voltage is above 0.8V.

PCB Layout

Due to the high integration of components required for power conversion in the FHT4623, it eliminates most of the tricky issues related to PCB layout. However, it is still necessary to optimize the PCB routing as much as possible to ensure its proper operation. Even with its high level of integration, good grounding and heat dissipation are still essential when using the module. The recommended layout diagram is shown in the following figure:

vias depends on the PCB design. For example, if the board uses very small vias, more thermal vias may be required to ensure adequate heat dissipation.

1.Place the R_FB resistor as close as possible to its corresponding pin.

2.Position the Cin capacitor as close as possible to the Vin and GND connections of the FHT4623.

3.Locate the Cout capacitor as close as possible to the Vout and GND connections of the FHT4623.

4.When placing the Cin and Cout capacitors, ensure that their grounding currents flow directly near or underneath the FHT4623.

5.Connect all GNDs to the largest possible copper pour area on the top layer, avoiding any breaks in the grounding connection between external components and the FHT4623.

For effective heat dissipation, use vias to connect the GND copper pour area to the internal grounding plane

 of the circuit board, providing both a good grounding connection and a thermal path to the internal plane of the board.

Since they are close to the internal power processing components, the FHT4623 can benefit from these vias

connecting to the internal GND plane of the PCB for heat dissipation. The optimal number of thermal

Package Description

Soldering and Storage Precautions

Recommended reflow soldering profile

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, and control the reflow soldering temperature within 245°C.