RICOH R1205x Technical data

R1205x SERIES

STEP-UP DC/DC CONVERTER

NO.EA-272-120508

OUTLINE

The R1205x Series are CMOS-based PWM control type step-up DC/DC converter ICs with low supply current. Each of these ICs consists of an NMOS FET, a diode, an oscillator, a PWM comparator, a voltage reference unit, an error amplifier, a current limit circuit, an under voltage lockout circuit (UVLO), an over-voltage protection circuit (OVP), a soft-start circuit, a Maxduty limit circuit, and a thermal shutdown protection circuit. This step-up DC/DC converter can be easily built with a few external components such as a coil, a resistor, and a capacitor. As the protection functions, the R1205x Series have a Lx peak current limit function, an over voltage protection (OVP) function, an under voltage lock out (UVLO) function and a thermal shutdown function.

The R1205x Series present the R1205x8xxA version that is optimized for the constant voltage power source, and the R1205x8xxB version that is optimized for driving the white LED with the constant current. The R1205x8xxB is an adjustable version that can change the LED brightness dynamically by using a 200Hz to 300kHz PWM signal toward the CE pin.

The R1205x Series are available in DFN1616-6B and TSOT-23-6 packages.

FEATURES

•	Input Voltage Range ..................................................	2.3V to 5.5V (R1205x8xxA)
		1.8V to 5.5V (R1205x8xxB)
• Supply Current ...........................................................		Typ. 800μA
• Standby Current .........................................................		Max. 5μA
• Feedback Voltage ......................................................		1.0V±1.5% (R1205x8xxA)
		0.2V±10mV (R1205x8xxB)
•	Oscillator Frequency ..................................................	Typ. 1.2MHz
•	Maximum Duty Cycle .................................................	Typ. 91%

•UVLO Function ························································ Typ.2.0V (Hys.Typ.0.2V) (R1205x8xxA)

		Typ.1.6V (Hys.Typ.0.1V) (R1205x8xxB)
•	Lx Current Limit Function...........................................	Select from 350mA, 700mA
•	Over Voltage Protection .............................................	Typ. 25V
•	LED dimming control (R1205x8xxB) ........................	by external PWM signal (Frequency 200Hz to 300kHz)
•	Thermal Protection Function......................................	Typ.150ºC(Hys.Typ.50ºC)
•	Switch ON Resistance ...............................................	Typ. 1.35Ω
•	Packages ...................................................................	DFN1616-6B, TSOT-23-6
•	Ceramic capacitors are recommended

APPLICATION

•Constant Voltage Power Source for portable equipment

•OLED power supply for portable equipment

•White LED Backlight for portable equipment

1

R1205x
BLOCK DIAGRAMS
			●R1205x8xxA
V			VIN		LX	VOUT
FB
Err. Amp.	PWM Comp.			UVLO
+
	+
–		R	Q	Driver
	–
vref			S	Control
Soft-start		Oscillator				OVP
		Slope Com-		Current	Current	Thermal
		pensation		Limit	sense	Shutdown
			∑
CE
CE					GND
V			● R1205x8xxB
			VIN		LX	VOUT
FB
Err. Amp.	PWM Comp.			UVLO
+
	+
–		R	Q	Driver
	–
vref			S	Control
PWM		Oscillator				OVP
Cntrl		Slope Com-		Current	Current	Thermal
EN
		pensation		Limit	sense	Shutdown
Shutdown			∑
delay
CE
CE					GND

2

R1205x

SELECTION GUIDE

The OVP threshold voltage, current limit, package and VFB/Auto discharge are user-selectable options.

Product Name	Package	Quantity per Reel	Pb Free	Halogen Free
R1205L8x1 -TR	DFN1616-6B	5,000 pcs	Yes	Yes
R1205N8x3 -TR-FE	TSOT-23-6	3,000 pcs	Yes	Yes

x : Designation of current limit.

(1) 350mA

(2) 700mA

: Designation of VFB.

(A) 1.0V

(B) 0.2V

3

R1205x

PIN CONFIGURATIONS

			• DFN1616-6B				• TSOT-23-6
Top View			Bottom View			6		5		4
6	5	4	4	5	6

1

2

3

3

2

1

(mark side)

1

2

3

PIN DESCRIPTIONS

• DFN1616-6B

Pin No	Symbol	Pin Description
1	CE	Chip Enable Pin ("H" Active)
2	VFB	Feedback Pin
3	LX	Switching Pin (Open Drain Output)
4	GND	Ground Pin
5	VIN	Input Pin
6	VOUT	Output Pin

) The tab is substrate level (GND). The tab is better to be connected to the GND, but leaving it open is also acceptable.

• TSOT-23-6

Pin No	Symbol	Pin Description
1	CE	Chip Enable Pin ("H" Active)
2	VOUT	Output Pin
3	VIN	Input Pin
4	LX	Switching Pin (Open Drain Output)
5	GND	Ground Pin
6	VFB	Feedback Pin

4

ABSOLUTE MAXIMUM RATINGS

R1205x

GND=0V

Symbol	Item	Rating		Unit
VIN	VIN Pin Voltage	−0.3 to	6.5	V
VCE	CE Pin Voltage	−0.3 to	6.5	V
VFB	VFB Pin Voltage	−0.3 to	6.5	V
VOUT	VOUT Pin Voltage	−0.3 to 28		V
VLX	LX Pin Voltage	−0.3 to 28		V
ILX	LX Pin Current	1000		mA
PD	Power Dissipation (DFN1616-6B)	640		mW
	Power Dissipation (TSOT-23-6)	460
Ta	Operating Temperature Range	−40 to	85	°C
Tstg	Storage Temperature Range	−55 to 125		°C

) For details regarding Power Dissipation and Standard Test Land Pattern, please refer to PACKAGE INFORMATION.

ABSOLUTE MAXIMUM RATINGS

Electronic and mechanical stress momentarily exceeded absolute maximum ratings may cause the permanent damages and may degrade the life time and safety for both device and system using the device in the field. The functional operation at or over these absolute maximum ratings is not assured.

RECOMMENDED OPERATING CONDITIONS (ELECTRICAL CHARACTERISTICS)

All of electronic equipment should be designed that the mounted semiconductor devices operate within the recommended operating conditions. The semiconductor devices cannot operate normally over the recommended operating conditions, even if when they are used over such conditions by momentary electronic noise or surge. And the semiconductor devices may receive serious damage when they continue to operate over the recommended operating conditions.

5

R1205x

ELECTRICAL CHARACTERISTICS

	• R1205x								(Ta=25°C)
	Symbol	Item	Conditions			Min.	Typ.	Max.	Unit
	VIN	Operating Input Voltage		R1205x8xxA		2.3		5.5	V
				R1205x8xxB		1.8		5.5
	IDD	Supply Current	VIN=5.5V, VFB=0V , LX at no load				0.8	1.2	mA
	Istandby	Standby Current	VIN=5.5V, VCE=0V				1.0	5.0	μA
	VUVLO1	UVLO Detector Threshold	VIN falling	R1205x8xxA		1.9	2.0	2.1	V
				R1205x8xxB		1.5	1.6	1.7
				R1205x8xxA			VUVLO1	2.3
	VUVLO2	UVLO Released Voltage	VIN rising				+0.2		V
				R1205x8xxB			VUVLO1	1.8
							+0.1
	VCEH	CE Input Voltage "H"	VIN=5.5V			1.5			V
	VCEL	CE Input Voltage "L"	VIN=1.8V					0.5	V
	RCE	CE Pull Down Resistance					1200		kΩ
	VFB	VFB Voltage Accuracy	VIN=3.6V	R1205x8xxA		0.985	1.000	1.015	V
				R1205x8xxB		0.19	0.2	0.21
	VFB/	VFB Voltage Temperature	VIN=3.6V, −40°C ≤ Ta ≤ 85°C				±150		ppm
	Ta	Coefficient							/°C
	IFB	VFB Input Current	VIN=5.5V, VFB=0V or 5.5V			-0.1		0.1	μA
	tstart	Soft-start Time		R1205x8xxB			2.0	3.0	ms
	RON	FET ON Resistance	ILX=100mA				1.35		Ω
	IOFF	FET Leakage Current	VLX=24V					3.0	μA
	ILIM	FET Current Limit			R1205x81xx	250	350	450	mA
					R1205x82xx	500	700	900
	VF	Diode Forward Voltage	ISW=100mA				0.8		V
	IDIODEleak	Diode Leakage Current	VOUT=24V, VLX=0V					10	μA
	fosc	Oscillator Frequency	VIN=3.6V, VFB=0V			1000	1200	1400	kHz
	Maxduty	Maximum Duty Cycle	VIN=3.6V, VFB=0V			86	91		%
	VOVP1	OVP Detect Voltage	VIN=3.6V, VOUT rising			24.2	25	25.8	V
	VOVP2	OVP Release Voltage	VIN=3.6V, VOUT falling				VOVP1		V
							-1.8
	TTSD	Thermal Shutdown	VIN=3.6V				150		°C
		Detect Temperature
	TTSR	Thermal Shutdown	VIN=3.6V				100		°C
		Release Temperature

6

R1205x

TYPICAL APPLICATIONS

●R1205x8xxA

●R1205x8xxB

L1

L1

C1

10μH

C1

10μH

1μF

1μF

C2

IN

LX

V

VIN

LX

0.22μF

CE

VOUT

C3

C2

CE

VOUT

R2

GND

VFB

R3

1μF

GND

VFB

R1

R1

10Ω

Recommended external Inductor

L1 (μH)

Parts No

Rated

Size(mm)

Current(mA)

10

LQH32CN100K53

450

3.2×2.5×1.55

10

LQH2MC100K02

225

2.0×1.6×0.9

10

VLF3010A-100

490

2.8×2.6×0.9

22

LQH32CN220K53

250

3.2×2.5×1.55

22

LQH2MC220K02

185

2.0×1.6×0.9

22

VLF3010A-220

330

2.8×2.6×0.9

R1205x8xxA Recommended external components

Rated voltage(V)

Part No.

C1

6.3

CM105B105K06

C2

25

GRM21BR11E105K

C3

25

220pF

R1

For VOUT Setting

R2

For VOUT Setting

R3

2kΩ

R1205x8xxB Recommended external components

Rated voltage(V)

Part No.

C1

6.3

CM105B105K06

C2

25

GRM21BR11E224

7