STMicroelectronics L6928 Technical data

L6928

HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS STEP DOWN REGULATOR

1 FEATURES

■2V TO 5.5V BATTERY INPUT RANGE

■HIGH EFFICIENCY: UP TO 95%

■INTERNAL SYNCHRONOUS SWITCH

■NO EXTERNAL SCHOTTKY REQUIRED

■EXTREMELY LOW QUIESCENT CURRENT

■1 A MAX SHUTDOWN SUPPLY CURRENT

■800mA MAX OUTPUT CURRENT

■ADJUSTABLE OUTPUT VOLTAGE FROM 0.6V

■LOW DROP-OUT OPERATION: UP TO100% DUTY CYCLE

■SELECTABLE LOW NOISE/LOW CONSUMPTION MODE AT LIGHT LOAD

■POWER GOOD SIGNAL

■±1% OUTPUT VOLTAGE ACCURACY

■CURRENT-MODE CONTROL

■1.4MHz SWITCHING FREQUENCY

■EXTERNALLY SYNCHRONIZABLE FROM 1MHz TO 2MHz

■OVP

■SHORT CIRCUIT PROTECTION

2 APPLICATIONS

■BATTERY-POWERED EQUIPMENTS

■PORTABLE INSTRUMENTS

■CELLULAR PHONES

■PDAs AND HAND HELD TERMINALS

■DSC

■GPS

Figure 2. Application Test Circuit

Figure 1. Packages

MSOP8 VFQFPN8

Table 1. Order Codes

Part Number	Package

L6928D	MSOP8 in Tube

L6928D013TR	MSOP8 in Tape & Reel

L6928Q1	VFQFPN8 in Tube

L6928Q1TR	VFQFPN8 in Tape & Reel

3 DESCRIPTION

The device is dc-dc monolithic regulator specifically designed to provide extremely high efficiency. L6928 supply voltage can be as low as 2V allowing its use in single Li-ion cell supplied applications. Output voltage can be selected by an external divider down to 0.6V. Duty Cycle can saturate to 100% allowing low drop-out operation. The device is based on a 1.4MHz fixed-frequency, current mode-architec- ture. Low Consumption Mode operation can be selected at light load conditions, allowing switching losses to be reduced. L6928 is externally synchronizable with a clock which makes it useful in noise-sen- sitive applications. Other features like Powergood, Overvoltage protection, Shortcircuit protection and Thermal Shutdown (150°C) are also present.

				L 4.7 H		VOUT=1.8V
				5		VOUT=1.8V
VIN=2V to 5.5V				5
VIN=2V to 5.5V	SYNC	7		LX	R2	C4
	VCC	7		R3	R2	C4
C1	VCC	6		500K	200K	10 F
C1	RUN	6		8		6.3V
10 F						6.3V
10 F		1
6.3V		1		PGOOD
6.3V
		2	4	3
		2	4	VFB	R1
	COMP			GND	R1
	COMP		C2	GND	100K
			C2
	D01IN1528		220pF
	D01IN1528
						Rev. 3
November 2005						1/10

L6928

Table 2. Absolute Maximum Ratings

Symbol

Parameter

Value

Unit

Input voltage

-0.3 to 6

Output switching voltage

-1 to VCC

Shutdown

-0.3 to VCC

Feedback voltage

-0.3 to VCC

Error amplifier output voltage

-0.3 to VCC

PGOOD

-0.3 to VCC

Synchronization mode selector

-0.3 to VCC

Ptot

Power dissipation at Tamb=70°C

0.45

Junction operating temperature range for MSOP8 package

-40 to 150

°C

Tstg

Storage temperature range

-65 to 150

°C

LX Pin

Maximum Withstanding Voltage Range Test Condition: CDF-

±1000

AEC-Q100-002- “Human Body Model” Acceptance Criteria:

Other pins

±2000

“Normal Performance’

Figure 3. Pin Connection

RUN

PGOOD

COMP

SYNC

VFB

VCC

GND

D01IN1239AMOD

Table 3. Thermal Data

Symbol

Parameter

Value

Unit

Rth j-amb

Thermal Resistance Junction to Ambient for MSOP8

Max.

180

°C/W

Table 4. Pin Functions

Name

Description

RUN

Shutdown input. When connected to a low level (lower than 0.4V) the device stops working.

When high (higher than 1.3V) the device is enabled.

COMP

Error amplifier output. A compensation network has to be connected to this pin. Usually a

220pF capacitor is enough to guarantee the loop stability.

VFB

Error amplifier inverting input. The output voltage can be adjusted from 0.6V up to the input

voltage by connecting this pin to an external resistor divider.

GND

Ground.

Switch output node. This pin is internally connected to the drain of the internal switches.

VCC

Input voltage. The start up input voltage is 2.2V (typ) while the operating input voltage range is

from 2V to 5.5V. An internal UVLO circuit realizes a 100mV (typ.) hysteresis.

SYNC

Operating mode selector input. When high (higher than 1.3V) the Low Consumption Mode is

selected. When low (lower than 0.5V) the Low Noise Mode is selected. If connected with an

appropriate external synchronization signal (from 1MHz up to 2MHz) the internal

synchronization circuit is activated and the device works at the same switching frequency.

PGOOD

Power good comparator output. It is an open drain output. A pull-up resistor should be

connected between PGOOD and VOUT (or VCC depending on the requirements). The pin is

forced low when the output voltage is lower than 90% of the regulated output voltage and goes

high when the output voltage is greater than 90% of the regulated output voltage. If not used the

pin can be left floating.

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L6928

Table 5. Electrical Characteristics

(Tj = 25°C, VCC = 3.6V unless otherwise specified); (*) Specification Referred to Tj from -40 to +125°C (2).

Symbol	Parameter	Test Condition		Min	Typ	Max	Unit

Vcc	Operating input voltage	After Turn on	*	2		5.5	V
Vcc ON	Turn On threshold				2.2		V
Vcc OFF	Turn Off threshold					2	V
Vcc hys	Hysteresis				100		mV
Rp	High side Ron	Vcc = 3.6V, Ilx =100mA			240	300	mΩ
			*			400

Rn	Low side Ron	Vcc = 3.6V, Ilx =100mA			215	300	mΩ
			*			400

Ilim	Peak current limit	Vcc = 3.6V		1	1.2	1.5	A
			*	0.85		1.65

	Valley current limit	Vcc = 3.6V		1	1.4	1.7	A
			*	0.9		1.85

Vout	Output voltage range			Vfb		Vcc	V

fosc	Oscillator frequency				1.4		MHz
fsync	Sync mode clock (1)			1		2	MHz
DC CHARACTERISTICS

Iq	Quiescent current (low	Vsync = 0V, no load,			230		µA
	noise mode)	VFB > 0.6V
	Quiescent current (low	Vsync = Vcc, no load,	*		25	50	µA
	cunsumption mode)	VFB > 0.6V
Ish	Shutdown current	RUN to GND, Vcc = 5.5V			0.2		µA
Ilx	LX leakage current (1)	RUN to GND, VLX = 5.5V,			1		µA
		Vcc = 5.5V
		RUN to GND, VLX = 0V,			1		µA
		Vcc = 5.5V
ERROR AMPLIFIER CHARACTERISTICS

Vfb	Voltage feedback			0.593	0.600	0.607	V

Ifb	Feedback input current (1)	VFB = 0.6V			25		nA
RUN

Vrun_H	RUN threshold high					1.3	V
Vrun_L	RUN threshold low			0.4			V

Irun	RUN input current (1)				25		nA
SYNC/MODE FUNCTION

Vsync_H	Sync mode threshold high					1.3	V
Vsync_L	Sync mode threshold low			0.5			V
PGOOD SECTION

VPGOOD	Power Good Threshold	VOUT = Vfb			90		%Vout
∆VPGOOD	Power Good Hysteresis	VOUT = Vfb			4		%Vout
VPgood(low)	Power Good Low Voltage	Run to GND				0.4	V
ILK-PGOOD	Power Good Leakage	VPGOOD = 3.6V			50		nA
	Current (1)
PROTECTIONS

HOVP	Hard overvoltage threshold	VOUT = Vfb			10		%Vout

Note: 1. Guaranteed by design

2. Specification over the -40 to +125°C Tj temperature range are assured by design, characterization and statistical correlation.

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