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RICOH RN5T659 User Guide

Summary

This constant frequency charge pump is engineered for advanced white LED lighting solutions, providing precise and efficient power management. It offers comprehensive control over output enable/disable, current limits (up to 115mA), and LDO functions using a single-wire serial pulse interface. The accompanying manual serves as a thorough technical guide for system designers, detailing electrical characteristics, multiple operational modes, critical protection features (UVLO, thermal shutdown), and optimal circuit implementation guidelines for reliable LED driver integration.

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Charge pump for White LED

RN5T659 Development Specifications

Rev. 1.2

RICOH COMPANY, LTD. Electronic Devices Company

This specification is subject to change without notice.

Page Summary Contents For RICOH RN5T659 User Guide

Page 1 Charge pump for White LED RN5T659 Development Specifications Rev. 1.2 RICOH COMPANY, LTD. Electronic Devices Company This specification is subject to change without notice.
Page 2 RN5T659 CHARGE PUMP FOR WHITE LED Table of Contents 1. Outline.............................................................................................................................................
Page 3 RN5T659 CHARGE PUMP FOR WHITE LED 1. Outline RN5T659 contains a constant frequency charge pump, which is optimized for White LED application. Output enable/disable, LEDs current and LDOs ON/OFF are in...
Page 4 RN5T659 CHARGE PUMP FOR WHITE LED 4. Pin Configuration Fig 4-1 Pin Configuration ©2009 Rev. 1.2 Page 4
Page 5 RN5T659 CHARGE PUMP FOR WHITE LED 5. Typical Application Circuit Fig 5-1 Typical Application Circuit ©2009 Rev. 1.2 Page 5
Page 6 RN5T659 CHARGE PUMP FOR WHITE LED 6. Pin Description No. Name I/O Description Notes 1 LEDCTL I ON/OFF control and Current setting of LED driver 2 C2M - Charge pump boost capacitor connection 3 C3P - C...
Page 7 RN5T659 CHARGE PUMP FOR WHITE LED 7. Functional Blocks 7.1 Single Wire Serial Pulse I/F of LDO1/2 RN5T659 has 2 Low Drop Output regulators, LDO1 and LDO2. At time of shipment, the output voltage can b...
Page 8 RN5T659 CHARGE PUMP FOR WHITE LED 7.2 LDO1/2 Electrical Characteristics Unless otherwise specified, VCCCOM=3.6V, Ta=25℃, Cout=1.0u F Symbol Parameter Condition Min Typ Max Units Output Voltage LDOUT*1...
Page 9 RN5T659 CHARGE PUMP FOR WHITE LED 7.3 Charge Pump RN5T659 drives up to 5 white LEDs with regulated constant current. Utilizing 1x/1.33x/1.5x charge pump modes achieves high-efficiency. On/off of LED i...
Page 10 RN5T659 CHARGE PUMP FOR WHITE LED 7.3.2 Backlight LED For maximized power efficiency, the charge pump operates 1x mode, 1.33x mode and 1.5x mode, where the operation mode is determined by comparing th...
Page 11 RN5T659 CHARGE PUMP FOR WHITE LED 7.3.3 Protection Circuit When any DIN_ pin is floating or grounded, VOUT voltage is limited below protection voltage by gating on/off charge pump. In case any LED fai...
Page 12 RN5T659 CHARGE PUMP FOR WHITE LED 7.3.6 Luminance Control RN5T659 charge pump drives 5 LEDs with regulated constant current for uniformed intensity. LEDCTL input enables/disables LED and adjusts curre...
Page 13 RN5T659 CHARGE PUMP FOR WHITE LED 7.3.7 Single Wire Serial Pulse I/F of LED Driver When LEDCTL goes high, LEDs are enabled at full luminance. After, the subsequent low going pulse reduces LED current ...
Page 14 RN5T659 CHARGE PUMP FOR WHITE LED 7.3.8 Charge Pump Electrical Characteristics Unless otherwise specified, VCCCP=3.6V, VCCCOM=3.6V, Ta=25℃, C1=C2=C3=1u F, Cout=2.2u F Symbol Parameter Condition Min Ty...
Page 15 RN5T659 CHARGE PUMP FOR WHITE LED 7.5 Thermal Shutdown Circuit Overheat state can be detected by comparing the output voltages from two temperature detection circuits, which have different temperature...
Page 16 RN5T659 CHARGE PUMP FOR WHITE LED 8. Electrical Characteristics 8.1 Absolute Maximum Ratings Symbol Parameter Condition Rated value Units VCC_abs Power Supply Voltage Battery Voltage Input Pins -0.3~6...
Page 17 RN5T659 CHARGE PUMP FOR WHITE LED 9. Package Information ©2009 Rev. 1.2 Page 17

Manual Details

Brand Ricoh
Pages 17
File Size 1.27 MB
Published May 31, 2026
61 views

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Frequently Asked Questions

What is the maximum current capability of this charge pump?

The device has a current capability of up to 115mA.

How is overheating addressed by the unit?

Overheat state is detected using two temperature detection circuits that compare output voltages, causing the device to turn off for protection.

What control features are available for the outputs?

Output enable/disable, LED current, and LDO ON/OFF can be individually controlled through a single wire serial pulse I/F.

What is the recommended working voltage range?

The operating voltage range is 2.7 V to 4.5 V, while recirculation is recommended between 3.0 V and 4.5 V.