Richtek RT8061AZQW Schematic [ru]

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RT8061A

3A, 1MHz, Synchronous Step-Down Converter

General Description

The RT8061A is a high efficiency synchronous, step-down DC/DC converter. Its input voltage range from 2.7V to 5.5V that provides an adjustable regulated output voltage from 0.6V to VIN while delivering up to 3A of output current. The internal synchronous low on resistance power switches increase efficiency and eliminate the need for an external Schottky diode. The switching frequency is fixed internally at 1MHz. The 100% duty cycle provides low dropout operation, hence extending battery life in portable systems. Current mode operation with internal compensation allows the transient response to be optimized over a wide range of loads and output capacitors. The RT8061A is operated in PWM/PSM mode to achieve high efficiency for a wide load range. The RT8061A is available in a WDFN-10L 3x3 package.

Ordering Information

RT8061A

Package Type

QW : WDFN-10L 3x3 (W-Type)

Lead Plating System

Z : ECO (Ecological Element with Halogen Free and Pb free)

Note :

Richtek products are :

`RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.

`Suitable for use in SnPb or Pb-free soldering processes.

Features

zHigh Efficiency : Up to 95%

zLow RDS(ON) Internal Switches : 69mΩ/49mΩ at VIN = 5V

zFixed Frequency : 1MHz

zNo Schottky Diode Required

z0.6V Reference Allows Low Output Voltage

zPWM/PSM Mode Operation

zLow Dropout Operation : 100% Duty Cycle

zOCP, UVP, OVP, OTP

zRoHS Compliant and Halogen Free

Applications

zPortable Instruments

zBattery-Powered Equipment

zNotebook Computers

zDistributed Power Systems

zIP Phones

zDigital Cameras

Pin Configurations

(TOP VIEW)

NC 1		10	PVIN
LX 2	GND	9	PVIN
LX 3	GND	8	SVIN
LX 3		8	SVIN
PGOOD 4		7	NC
EN 5	11 6		FB

WDFN-10L 3x3

Marking Information

	11 : Product Code
11 YM	YMDNN : Date Code
DNN

is a registered trademark of Richtek Technology Corporation.

DS8061A-04 September 2012	www.richtek.com
	1

RT8061A
Typical Application Circuit
	RT8061A		LOUT
	4 PGOOD		LOUT
PGOOD	4 PGOOD		LX 2, 3	VOUT
R1			RFB1	COUT
VIN	9, 10 PVIN		RFB1	CFF
VIN	9, 10 PVIN		FB 6
CIN	8 SVIN
	8 SVIN		RFB2
	C1		RFB2
	C1
Chip Enable	5 EN	GND 11 (Exposed Pad)
	5 EN	GND 11 (Exposed Pad)

Functional Pin Description

Pin No.	Pin Name	Pin Function
1, 7	NC	No Internal Connection.

2, 3	LX	Switch Node. Connection this pin to the inductor.

4	PGOOD	Power Good Indicator. This pin is an open drain logic output that is pulled to
4	PGOOD	ground when the output voltage is less than 90% of the target output voltage.

5	EN	Enable Control. Pull high to turn on. Do not float.
6	FB	Feedback. This pin receives the feedback voltage from a resistive voltage divider
6	FB	connected across the output.
		connected across the output.
8	SVIN	Signal Input. Decouple this pin to GND with at least 1μF ceramic cap.
9, 10	PVIN	Power Input. Decouple this pin to GND with at least 4.7μF ceramic cap.
11 (Exposed Pad)	GND	The exposed pad must be soldered to a large PCB and connected to GND for
11 (Exposed Pad)	GND	maximum power dissipation.
		maximum power dissipation.

Function Block Diagram

PVIN

ISEN

OSC

Slope

PGOOD

Com

0.6V

Output

Clamp

Limit

Int-SS

Driver

0.72V

Control

0.54V

Logic

PGOOD

NISEN

0.4V

Zero Current

POR

SVIN

VREF

OTP

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8061A-04 September 2012

						RT8061A
Absolute Maximum Ratings (Note 1)
z Supply Input Voltage, PVIN, SVIN--------------------------------------------------------------------------------						−0.3V to 6.5V
z LX Pin Voltage---------------------------------------------------------------------------------------------------------						(VIN + 0.3V) to 6.8V
z Other I/O Pin Voltage ------------------------------------------------------------------------------------------------						−0.3V to 6.5V
z Power Dissipation, PD @ TA = 25°C
WDNF-10L 3x3 --------------------------------------------------------------------------------------------------------						1.429W
z Package Thermal Resistance (Note 2)
WDFN-10L 3x3, θJA	--------------------------------------------------------------------------------------------------					70°C/W
WDFN-10L 3x3 θJC --------------------------------------------------------------------------------------------------						8.2°C/W
z Junction Temperature ------------------------------------------------------------------------------------------------						150°C
z Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------						260°C
z Storage Temperature Range ---------------------------------------------------------------------------------------						−65°C to 150°C
z ESD Susceptibility	(Note 3)
HBM (Human Body Model) -----------------------------------------------------------------------------------------						2kV
Recommended Operating Conditions				(Note 4)
z Supply Input Voltage, PVIN, SVIN--------------------------------------------------------------------------------						2.7V to 5.5V
z Junction Temperature Range ---------------------------------------------------------------------------------------						−40°C to 125°C
z Ambient Temperature Range ---------------------------------------------------------------------------------------						−40°C to 85°C
Electrical Characteristics
(VIN = 3.3V, TA = 25°C, unless otherwise specified)
Parameter		Symbol	Test Conditions		Min	Typ	Max	Unit
Feedback Reference Voltage		VREF			0.594	0.6	0.606	V
Feedback Leakage Current		IFB			--	0.1	0.4	μA
DC Bias Current			Active , VFB = 0.7V, Not Switching		--	110	140	μA
DC Bias Current			Shutdown		--	--	1	μA
			Shutdown		--	--	1

Output Voltage Line Regulation			VIN = 2.7V to 5.5V IOUT = 0A		--	0.3	--	%/V
Output Voltage Load Regulation			IOUT = 0A to 3A		−1	--	1	%
Switch Leakage Current			VEN = 0A		--	--	1	μA
Switching Frequency					0.8	1	1.2	MHz

Switch On Resistance, High		RDS(ON)_P	VIN = 5V		--	69	--	mΩ
Switch On Resistance, Low		RDS(ON)_N	VIN = 5V		--	49	--	mΩ
PMOS Current Limit (latch-off)		ILIM			4	--	--	A
Under Voltage Lockout		VUVLO	VIN Rising		2.2	2.4	2.6	V
Threshold		VUVLO	VIN Falling		2	2.2	2.4	V
			VIN Falling		2	2.2	2.4

EN Threshold	Logic-High	VIH			1.6	--	--	V
Voltage	Logic-Low	VIL			--	--	0.4	V
Voltage

EN Pull Low Resistance					--	500	--	kΩ


Copyright ©2012 Richtek Technology Corporation. All rights reserved.				is a registered trademark of Richtek Technology Corporation.
DS8061A-04 September 2012							www.richtek.com

RT8061A

Parameter	Symbol	Test Conditions	Min	Typ	Max	Unit

Over Temperature	TSD		--	150	--	°C
Protection (latch-off)	TSD		--	150	--	°C
Protection (latch-off)
Soft-Start Time	tSS		500	--	--	μs
VOUT Discharge Resistance			--	100	--	Ω

VOUT Over Voltage
Protection (latch-off, delay			115	120	130	%
time = 10μs)
VOUT Under Voltage			57	66	75	%
Lockout Threshold			57	66	75	%
(latch-off)
Power Good		Measured FB, With Respect to VREF	85	90	--	%

Power Good Hysteresis			--	5	--	%

Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability.

Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package.

Note 3. Devices are ESD sensitive. Handling precaution is recommended.

Note 4. The device is not guaranteed to function outside its operating conditions.

Copyright ©2012 Richtek Technology Corporation. All rights reserved.	is a registered trademark of Richtek Technology Corporation.
www.richtek.com	DS8061A-04 September 2012

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