RICOH RP901K Series PWM VFM Step-down DC DC Converter with Synchronous Rectifier, VR and VD Data Manual and User Guide

RP901K Series

PWM/VFM Step-down DC/DC Converter with Synchronous Rectifier Equipped with VR and VD

The RP901K Series are CMOS-based PWM/VFM step-down DC/DC converters equipped with voltage regulator and voltage detector. The DC/DC converter can be selected from two control types - fixed PWM control or PWM/VFM auto switching control in which mode automatically switches to high-efficiency VFM mode in low output current. RP901K was developed for applications that require multiple power supplies such as storage devices. It integrates an 800m A∗ output current step-down DC/DC converter, a 600m A output current LDO regulator, and a voltage detector with a built-in delay circuit into a small package. The regulator can be started after soft start of the DC/DC converter by sequence control.

FEATURES • Supply Current (IDD1)·······················Typ. 460μA (VIN=VCE=5.5V,VOUT1= 0V) (VR Section) • Supply Current (IDD2)·······················Typ. 170μA (VIN=VCE=5.5V, • VR Output Voltage Range (VOUT2)····· 2.5V to 3.3V (internally fixed) VOUT1=5.5V, B/C Version) • VR Output Voltage Accuracy·········· ± 1% • Standby Current (Istandby)··················Max. 5μA (VIN=5.5V, CE="L") • Fold-back Protection Circuit ········· Current limit Typ. 70m A • Input Voltage Range (VIN) ···············4.5V to 5.5V • Start-up Time·································· Typ. 2ms after DC/DC soft start period (A/B Version)

(DC/DC Section) Typ. 50μs after DC/DC UVLO released (C Version)

• DC/DC Output Voltage Range (VOUT1) ··1.2V to 1.8V (internally fixed) • Auto-Discharge function • DC/DC Output Voltage Accuracy····± 2% (VD Section) • Oscillator Frequency (fosc)···············1.2MHz • VD Detector Threshold Range (-VDET)··· 2.0V to 3.0V (internally fixed) • UVLO Detect Voltage (VUVLO) ·········Typ. 3.5V (A Version, VR Output voltage monitoring) • Soft Start Time (tstart)···························Typ. 1ms 3.0V to 5.0V (internally fixed) • Coil-current Limit Circuit ·················Current limit Typ. 1.4A (B/C Version, Input voltage monitoring) • Reset Protection Circuit··················Delay time for protection Typ. 0.1ms • VD Detector Threshold Accuracy··· ± 2%

(B/C Version) • VD Output Delay Time ··················· Typ. 50ms • Thermal Shutdown Circuit·············· Stops at 165°C • Package ········································· DFN(PLP)2527-10

∗) This is an approximate value, because output current depending on conditions and external parts.

BLOCK DIAGRAMS TYPICAL APPLICATION

RP901Kxxx A ff ic ie RP901Kxxx B/C

PVDD PVDD

Chip Ramp Current Chip Ramp Current

CE Compensation Feedback CE Enable Compensation Feedback R1 50KΩ

Enable

OSC Current AVDD VDOUT VDOUT

OSC Current LX

Protection LX Protection

PVDD VOUT1

Vref “H”active L1

Vref PWM Switching Switching

PWM/VFM Control CE LX VOUT1

Control Control Control 4.7μH

Soft VOUT1 Soft VOUT1 PGND VOUT2 VOUT2

Start UVLO Start UVLO

C1 AGND C2 C3

PGND PGND

AVDD Thermal Ceramic Ceramic Ceramic

Thermal Vref Shutdown AGND

Vref Shutdown AGND

Delay Circuit

VDOUT Vref Current VDOUT

Vref Current VOUT2 Protection L1 4.7μH (VLF4014AT-4R7M1R1 : TDK)

VOUT2 Protection

Delay Circuit

SELECTION GUIDE

.∗ : Select from (.A.) Fixed PWM, without delay time for protection,

Halogen Free Package Q'ty per Reel Part No.

VR starts after DC/DC soft start period, and VD monitoring VR output voltage,

DFN(PLP)2527-10 5,000 pcs RP901K .xxx∗ -TR (.B.) PWM/VFM auto switching control, with delay time for protection,

VR starts after DC/DC soft start period, and VD monitoring VR input voltage or

.xxx :Specify a combination of output voltage and detector threshold

(.C.) PWM/VFM auto switching control, with delay time for protection,

using serial numbers.

VR starts after DC/DC UVLO released, and VD monitoring VR input voltage.

PACKAGE TYPICAL CHARACTERISTIC

DFN(PLP)2527-10 RP901K Efficiency vs. Output Current

1 CE 6 PVDD SET VOUT1=1.8V, VIN=5.0V

Bottom View Top View

2 VDOUT 7 NC 3 AGND∗∗ 8 VOUT1

4 PGND∗∗ 9 AVDD 5 LX 10 VOUT2

∗) The tab is substrate level (GND). ∗∗) No.3 pin and No.4 pin, No.6 pin and No.9 pin must be wired each other

A version

when it is mounted on board. B version

Output Current IOUT1 (m A)

APPLICATIONS • Power source for hand-held equipment, DVD and CD drives • Power source for battery-powered equipment No.EK-156-111001 Step-down DC/DC Converter