Purpose
The RT9458 is a switch-mode single cell Li-Ion/Li-Polymer battery charger for portable applications. It integrates a synchronous PWM controller, power MOSFETs, input current sensing, high accuracy voltage regulation and charge termination circuits. The RT9458 also features USB On-The-Go (OTG). This document explains the function and use of the RT9458 evaluation board (EVB), and provides information to enable operation, modification of the evaluation board and circuit to suit individual requirements.
Introduction
General Product Information
The RT9458 is a switch-mode single cell Li-Ion/Li-Polymer battery charger for portable applications. It integrates a synchronous PWM controller, power MOSFETs, input current sensing, high accuracy voltage regulation and charge termination circuits. The RT9458 also features USB On-The-Go (OTG).
Product Feature
- Support Quick Start for Charger
- High Accuracy Voltage/Current Regulation
- Input Current Regulation : 100mA/500mA/700mA/1A
- Minimum Input Voltage Regulation : 4.1V to 4.7V Per 0.1V Step
- Charge Voltage Regulation Accuracy : ±1% (0 to 85°C)
- Charge Current Regulation Accuracy : ±5%
- Built-In Input Current Sensing and Limiting
- Integrated Power MOSFETS for Up to 1.55A Charge Rate
- Integrated Sensing Resistors for Charging Current Sensing
- Synchronous 1.5MHz Fixed Frequency PWM Controller with Up to 95% Duty Cycle
- Reverse Leakage Protection to Prevent Battery Drainage
- Thermal Regulation and Protection
- Over-Temperature Protection
- Input Over-Voltage Protection
- IRQ Output for Communication with I2C
- Automatic Charging
- RoHS Compliant and Halogen Free
Key Performance Summary Table
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Key Features
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Evaluation Board Number : PCB099_V1
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Input Voltage
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4.3V to 6V
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Output Voltage
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3.5V to 4.44V
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Max Output Current
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1.55A
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Package Type
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RT9458WSC, WL-CSP-20B 2.1x1.87 (BSC)
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Bench Test Setup Conditions
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.
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Test point/
Pin name
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Signal
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Comment (expected waveforms or voltage levels on test points)
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VIN
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Input voltage
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Power input.
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STAT
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Interrupt
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IRQ output node. Open-drain output. Connect a 10kΩ pull up resistor.
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MID
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VMID
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Connection point between reverse blocking MOSFET and high-side MOSFET.
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OTG
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OTG
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Boost mode control input or current regulation setting for average input current.
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ISNSIN
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ISNSIN
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Charge current sense input.
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LX
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LX
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Switch node.
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SCL
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SCL
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Clock input for I2C. Open-drain output. Connect a 10kΩ pull-up resistor.
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BOOT
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BOOT
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Bootstrap supply for high-side MOSFET. Connect a capacitor between BOOT and LX.
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SDA
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SDA
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Data input for I2C. Open-drain output. Connect a 10kΩ pull-up resistor.
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VPULL
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Pull high voltage
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Pull high voltage source for SDA, SCL and IRQ.
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VBAT
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VBAT
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Feedback voltage input for battery.
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BATS
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BATS
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Test pin for measure battery voltage.
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GND
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GND
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Ground.
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Power-up & Measurement Procedure
1. Connect power supply termination to VIN Pin and GND Pin respectively.
2. Set PSU Voltage 4.3 to 6V and then power on PSU.
3. Check VBAT = 4.2V ±1% on EVB.
4. Switch charger work normally.
Schematic, Bill of Materials & Board Layout
EVB Schematic Diagram
Bill of Materials
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Reference
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Qty
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Part Number
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Description
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Package
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Manufacturer
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U1
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1
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RT9458WSC
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Switching Charger
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WL-CSP-20B
2.1x1.87 (BSC)
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RICHTEK
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C2
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1
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GRM155R61E474KE01
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0.47µF/25V/X5R
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0402
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muRata
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C3
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1
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GRM155R71E473KA88D
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47nF/25V/X7R
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0402
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muRata
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C4
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1
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GRM188R61C106KAAL
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10µF/16V/X5R
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0603
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muRata
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C6
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1
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C1005X7R1C104K050BC
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100nF/16V/X7R
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0402
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TDK
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C10
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1
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GRM185R60J106ME15
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10µF/6.3V/X5R
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0603
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muRata
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L1
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1
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DFE252012F-1R0M
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1µH
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2.5x2mm
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muRata
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R1
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1
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RL10FTNR056
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56mΩ
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0805
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TA-I
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R2, R3, R4, R5
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4
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WR04X1002FTL
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10kΩ
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0402
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WALSIN
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PCB Layout
Top View (1st layer)
PCB Layout—Inner Side (2nd Layer)
PCB Layout—Inner Side (3rd Layer)
Bottom View (4th Layer)