RICOH R1202x User Manual

R1202x Series

PWM Step-up DC/DC Converter for White LED / PMOLED and General Use with shutdown function

The R1202x Series are CMOS-based PWM step-up DC/DC converters, which are optimized to drive white LEDs and OLED with constant current. There are two types. The A/B versions are optimized for the general use or the drive of PMOLED, and the D version is optimized for the serial drive of white LED with constant current. The R1202x includes an under-voltage lockout circuit (UVLO), a soft-start circuit, and an over-voltage protection circuit (OVP), a thermal shutdown circuit. By simply using an inductor, divider resisters, and capacitors as external components, OLED and white LEDs can be driven with high efficiently. At the standby mode, the internal NPN transistor can separate the output from the input. (Shutdown function) The A/B version with auto-discharge function is selectable. D Version can set white LED current with feedback resister (R1). The brightness of the LEDs and the soft-start time can be adjusted by applying a PWM signal (200Hz to 300kHz) to the CE pin. In addition to DFN1616-6B, 0.95mm thickness TSOT-23-6 is available.

FEATURES

• Supply Current (IDD)························Typ. 800μA (VIN= 5.5V, VFB = 0V, Lx at no load) • UVLO Detect Voltage (VUVLO)···Typ. 2.0V				(A/B Version)
• Standby Current (Istandby)··················Max. 5μA (VIN= 5.5V, VCE = 0V)			Typ. 1.6V	(D Version)
• Input Voltage Range (VIN)···············2.3V to 5.5V (A/B Version)		• Coil-current Limit Circuit ··········Current Limit Typ. 350mA
	1.8V to 5.5V (D Version)		/ Typ. 700mA selectable
• Feedback Voltage (VFB) ·················1.0V (A/B Version)		• Over Voltage Protection Circuit (OVP)
	0.2V (D Version)	• Soft Start Time (tstart) ················Typ. 2ms (A/B Version)
• Feedback Voltage Accuracy ···········± 1.5% (A/B Version)			Controllable by PWM signal
	± 10mV (D Version)		to the CE pin (D Version)
• Oscillator Frequency (fosc)···············1.2MHz		• Thermal Shutdown Circuit ·······Stops at 150°C
• Oscillator Maximum Duty Cycle (Maxduty)···Typ. 91%		• Auto-Discharge function ··········A Version
		• Packages·································DFN1616-6B, TSOT-23-6
	BLOCK DIAGRAMS
	R1202xxxxA	R1202xxxxB	R1202xxxxD

(With Auto-Discharge function, VFB=1.0V)

VFB		VIN		LX	VOUT
			UVLO
Error Amp.	PWM Comp.				Switch
					Control
	R	Q	Driver
	S		Control
Vref	OSC				OVP
Soft Start	Slope		Current	Current	Thermal
	Compensation		Limit	Sense	Shutdown
Chip Enable
	Σ
CE				GND

(Without Auto-Discharge function, VFB=1.0V) (Without Auto-Discharge function, VFB=0.2V

VFB		VIN		LX	VOUT
			UVLO
Error Amp.	PWM Comp.				Switch
					Control
	R	Q	Driver
	S		Control
Vref	OSC				OVP
Soft Start	Slope		Current	Current	Thermal
	Compensation		Limit	Sense	Shutdown
Chip Enable
	Σ
CE				GND

VFB			VIN		LX	VOUT
				UVLO
Error Amp.		PWM Comp.				Switch
						Control
		R	Q	Driver
		S		Control
Vref
PWM		OSC				OVP
Cntrl	EN
	Shutdown	Slope		Current	Current	Thermal
		Compensation		Limit	Sense	Shutdown
	delay
Chip Enable		Σ
	CE				GND

SELECTION GUIDES

TYPICAL APPLICATIONS

Halogen Free

Package

Q'ty per Reel

Part No.

DFN1616-6B

5,000 pcs

R1202L

.x$.

1

.

-TR

R1202L

.y$

1

.#

-TR

TSOT-23-6

3,000 pcs

R1202N

.x$.

3

.

-TR-FE

R1202N

.y$.

3

.#

-TR-FE

.x. : Specify the OVP voltage.

(3) OVP : 14V, (4) OVP : 17V, (5) OVP : 19V, (6) OVP : 21V

(7) OVP : 23V

.y. : Specify the OVP voltage.

(3) OVP : 14V, (7) OVP : 23V

.$. : Specify the Coil Current limit.

(1) Typ. 350mA, (2) Typ. 700mA

. : (.A.) with auto-discharge function, VFB=1.0V. (.B.) without auto-discharge function, VFB=1.0V.

# : (.D.) without auto-discharge function, VFB=0.2V.

	R1202xxxxA/B		R1202xxxxD
		L1		L1
		10μH		10μH
	C1		C1
	1μF		1μF		C2
					0.22μF
	VIN	LX	VIN	LX
	CE	VOUT	CE	VOUT
		C3	C2
		R2	1μF
		R3	GND	VFB
	GND	VFB			R1
		R1			10Ω

PACKAGES (Top View)

				DFN1616-6B														TSOT-23-6
				6		5				4							6			5			4
				1		2				3							1			2			3
			1	CE					4		GND					1	CE						4			LX
			2	VFB					5		VIN					2	VOUT						5			GND
			3	LX					6		VOUT					3	VIN						6			VFB

) The tab is substrate level (GND).

TYPICAL CHARACTERISTIC

R1202N713D Efficiency vs. LED Output Current 4LEDs (10μF) 5LEDs (10μF)

	90					90
	85					85
	80					80
(%)	75				(%)	75
Efficiency	70				Efficiency	70
	65					65
	60			Vin=3V		60
				Vin=3.6V
	55			Vin=4.2V		55
				Vin=5V
	50					50
	0	5	10	15	20

			Vin=3V
			Vin=3.6V
			Vin=4.2V
			Vin=5V
0	5	10	15	20

Output Current ILED (mA)

Output C urrent ILED (mA)

APPLICATIONS

• OLED power supply for hand-held equipment • White LED backlight for hand-held equipment

No.EK-255-111001

Step-up DC/DC Converter

R1202x Series

Step-up DC/DC Converter

PWM Step-up DC/DC Converter for White LED / PMOLED and General Use with shutdown function

R1202x Version Lineup

Product Name	R1202xxxxA/B			R1202xxxxD
Application	PMOLED, General Use			White LED (Serial drive)
VFB Voltage	1.0V			0.2V
Input Voltage Range	2.3V to 5.5V			1.8V to 5.5V
OVP Voltage	Select from 14V, 17V, 19V, 21V, 23V			Select from 14V, 23V
Function	Thermal Shutdown Circuit			Thermal Shutdown Circuit
	Shutdown Function			Shutdown Function
	Auto-Discharge Function
Output Capacitor	1μF to 4.7μF			0.22μF to 1μF
Comment	The Method of Output Voltage Setting			LED Current setting
	Output Voltage= (R1+ R2) / R1			When CE pin input is "H" (Duty=100%), LED current can be set
				with feedback resistor (R1).
	L1				L1
	10μH			ILED=0.2 / R1	10μH
	C1
				C1
	1μF			1μF			C2
							0.22μF
	VIN	LX			VIN	LX
	CE	VOUT			CE	VOUT
		C3	C2
		R2	1μF
		R3			GND	VFB
	GND	VFB					R1
		R1					10Ω
	The total value of R1 and R2 should be equal or less			LED Dimming Control
	than 300kΩ.			The LED brightness can be controlled by inputting the PWM
	Voltage rating of capacitor (C2) is recommended to			signal to the CE pin. The current of LEDs when High-Duty of the
	use 1.5 times or more the output setting voltage.			CE input is ”Hduty” reaches the value as in next formula.
				ILED=Hduty × VFB / R1

Soft-Start Time

The soft start time is set to Typ. 2ms within the IC. The frequency of the PWM signal is using the range between 200Hz to 300kHz. When controlling the LED brightness by the PWM signal of 20kHz or less, the increasing or decreasing of the inductor current might be make a sounds in the hearable sound wave area. In that case, please use the PWM signal in the high frequency area.

In case of 6 lights or more, we recommends the R1205x Series and R1218x Series*.

More than 5 lights of R1218x Series requires an external diode and OVP Voltage is set up to 31.5V. (Maximum rating of VOUT pin is 34V)

) For detail, please check our website.

The currently available information as of October 2011 is provided in this New Product News.

EK-255-111001