RICOH RP505K SERIES Data Sheet

RP505K Series

1A∗ PWM/VFM Step-down DC/DC Converter with Synchronous Rectifier

The RP505K Series are low supply current CMOS-based PWM/VFM step-down DC/DC converters with synchronous rectifier. RP505K can be selected from two control types by input signal to the MODE pin - forced PWM control or PWM/VFM auto switching control in which mode automatically switches to high-efficiency VFM mode in low output current. The xx1A/B version with an internally fixed output voltage type and the 001C version with an externally adjustable output voltage type are available. RP505K includes a soft start circuit, an under-voltage lockout circuit (UVLO), thermal shutdown circuit and a latch protection circuit. By simply using an inductor, (resistors) and capacitors as external components, a high-efficiency step-down DC/DC converter can be easily configured. The small inductor (2.2μH) and output capacitor (10μF) can be used by the switching of 2.25MHz. A 2mm square compact DFN(PLP)2020-8 package is available.

FEATURES • Supply Current (IDD1)·················· Typ. 500μA (Switching) • Oscillator Maximum Duty Cycle (Maxduty)···· Min. 100% • Supply Current (IDD2)·················· Typ. 40μA (No switching, VFM) • UVLO Detect Voltage (VUVLO) ·············· Typ. 2.0V • Supply Current (IDD2)·················· Typ. 500μA (No switching, PWM) • Soft Start Time (tstart) ···························· Typ. 0.15ms • Standby Current (Istandby) ············ Max. 5μA (CE="L") • Thermal Shutdown Circuit ··················· Stops at 140°C. • Input Voltage Range (VIN) ·········· 2.3V to 5.5V (VSET ≥ 0.8V) • Coil-current Limit Circuit ···················· Current limit Typ. 1.7A • Output Voltage Range (VOUT)····· 0.6V to 3.3V∗∗ (Internally fixed, RP505Kxx1A/B) • Latch Protection Circuit ······················· Delay time for protection

0.8V to 3.3V (Externally djustable, RP505K001C) Typ. 1.5ms (Feedback Voltage : 0.6V) • Auto-discharge Function······················ B Version

• Output Voltage Accuracy ··········· ± 1.5% (Feedback Voltage Accuracy : ± 9m V) • MODE Pin ·········································· "H": forced PWM control, • Output Current (IOUT)·················· 1A∗ "L": PWM/VFM auto switching control • Oscillator Frequency (fosc)·········· 2.25MHz • Package··············································· DFN(PLP)2020-8

∗) This is an approximate value, because output current depends on conditions and external parts. ∗∗) For less than 0.8V, the input voltage range is limited. For details, please refer to the datasheet.

BLOCK DIAGRAMS RP505Kxx1A/B RP505K001C (Internally fixed output voltage type) (Externally adjustable output voltage type)

PVIN PVIN

Ramp Current Ramp Current Compensation Feedback Compensation Feedback

ffi ci en cy

AVIN UVLO Thermal Thermal

Shutdown Current AVIN UVLO Current

Detector LX Shutdown

Detector LX

Soft Start Vref Switching Switching

Control Soft Start Vref Control

Mode OSC PGNDMODE Mode PGNDMODE

Control Control OSC

Chip Chip

CE Enable CE

Enable

VOUT VFB

AGND AGND

SELECTION GUIDES TYPICAL APPLICATIONS

Halogen Free Package Q'ty per Reel Part No. RP505Kxx1A/B RP505K001C

RP505K.xx.1.∗ -TR VIN VOUT VIN VOUT

DFN(PLP)2020-8 5,000 pcs PVIN LX PVIN LX

RP505K.00.1.$.-TR R1 C1

CIN AVIN VOUT COUT CIN AVIN VFB COUT 4.7μF 10μF 4.7μF 10μF

.xx. : Specify the output voltage within the range of R2

0.6V (.06.) to 3.3V (.33.) in 0.1V steps. CE AGND CE AGND

(For externally adjustable output voltage type (.00.))

MODE PGND MODE PGND

.∗ : Select from (.A.) internally fixed output voltage type, without auto-discharge function or

(.B.) internally fixed output voltage type, with auto-discharge function. L : MIPSA2520D2R2 (FDK) Set Output Voltage Inductor 0.6V ≤ VSET < 1.6V 1.0μH or more

.$. : (.C.) externally adjustable output voltage type, CIN : C1608JB0J475K (TDK)

1.6V ≤ VSET ≤ 2.3V 1.5μH or more

without auto-discharge function COUT : C1608JB0J106M (TDK)

2.3V < VSET ≤ 3.3V 2.2μH or more

PACKAGE TYPICAL CHARACTERISTIC

DFN(PLP)2020-8 RP505K331x Efficiency vs. Output Current

Bottom View Top View

1 MODE LX 2 CE PGND∗∗ VIN=4.3V, PWM/VFM

∗∗ VIN=5.0V, PWM/VFM

3 AVIN AGND∗∗

VIN=4.3V, forced PWM

4 PVIN VOUT or VFB VIN=5.0V, forced PWM

∗) The tab is substrate level (GND). ∗∗) No.3 pin and No.4 pin, No.6 pin and No.7 pin must be wired together when it is mounted on board.

Output Current IOUT (m A)

APPLICATIONS • Power source for battery-powered equipment • Power source for hand-held communication equipment, cameras, and VCRs • Power source for Wireless LAN terminals No.EK-273-121001 Step-down DC/DC Converter