RT4803B 2.5MHz Synchronous Boost Regulator Evaluation Board

General Description

The RT4803B allows systems to take advantage of new battery chemistries that can supply significant energy when the battery voltage is lower than the required voltage for system power ICs. By combining built-in power transistors, synchronous rectification, and low supply current, this IC provides a compact solution for systems using advanced Li-Ion battery chemistries.

The RT4803B is a boost regulator designed to provide a minimum output voltage from a single-cell Li-Ion battery, even when the battery voltage is below the system minimum. In boost mode, output voltage regulation is guaranteed up to a maximum load current of 2000mA. The quiescent current in shutdown mode is less than 1µA, which maximizes battery life. The regulator transitions smoothly between bypass and normal boost modes. The device can be forced into bypass mode to reduce quiescent current.

Performance Specification Summary

Summary of the RT4803B Evaluation Board performance specificiaiton is provided in Table 1. The ambient temperature is 25°C.

Table 1. RT4803B Evaluation Board Performance Specification Summary

Power-up Procedure

Suggestion Required Equipments

• RT4803B Evaluation Board
• DC power supply capable
• Electronic load

Quick Start Procedures

The Evaluation Board is fully assembled and tested. Follow the steps below to verify board operation. Do not turn on supplies until all connections are made. When measuring the output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the output voltage ripple by touching the probe tip and ground ring directly across the last output capacitor.

Proper measurement equipment setup and follow the procedure below.

1) With power off, connect the input power supply to the VIN and GND pins.

2) With power off, connect the electronic load between the VOUT and nearest GND pins.

3) When pulling the VSEL pin to L, the default output voltage setting is V_OUT = 3.15V. When pulling the VSEL pin to H, the default output voltage setting is V_OUT = 3.4V.

4) When pulling the nBYP and EN pins to H, the device operate in boost and auto bypass mode. The detailed mode is defined in Table 2.

5) Turn on the power supply at the input. Make sure that the input voltage does not exceeds 5V on the Evaluation Board.

6) Check for the proper output voltage using a voltmeter.

7) Once the proper output voltage is established, adjust the load within the operating ranges and observe the output voltage regulation, ripple voltage, efficiency and other performance.

Table 2

Detailed Description of Hardware

Headers Description and Placement

Carefully inspect all the components used in the EVB according to the following Bill of Materials table, and then make sure all the components are undamaged and correctly installed. If there is any missing or damaged component, which may occur during transportation, please contact our distributors or e-mail us at evb_service@richtek.com.

Test Points

The EVB is provided with the test points and pin names listed in the table below.

Bill of Materials

Typical Applications

EVB Schematic Diagram

1. The capacitance values of the input and output capacitors will influence the input and output voltage ripple.

2. MLCC capacitors have degrading capacitance at DC bias voltage, and especially smaller size MLCC capacitors will have much lower capacitance.

Measure Result

Note: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the output voltage ripple by touching the probe tip directly across the output capacitor.

Evaluation Board Layout

Figure 1 to Figure 4 are RT4803B Evaluation Board layout.

Figure 1. Top View (1^st layer)

Figure 2. PCB Layout—Inner Side (2^nd Layer)

Figure 3. PCB Layout—Inner Side (3^rd Layer)

Figure 4. Bottom View (4^th Layer)