STMicroelectronics L6928 Technical data

L6928

Fi

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

■ 1µA 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

gure 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-architec­ture. 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-sen­sitive applications. Other features like Powergood,
Overvoltage protection, Shortcircuit protection and
Thermal Shutdown (150°C) are also present.

Figure 2. Application Test Circuit

November 2005

V

=2V to 5.5V

IN

C1

10µF

6.3V

SYNC LX

V

CC

RUN

D01IN1528

5

7

6

1

24

COMP GND

C2

220pF

8

3

L 4.7µH

PGOOD

VFB

R3

500K

R2

200K

R1

100K

=1.8V

V

OUT

C4

10µF

6.3V

Rev. 3

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L6928

Table 2. Absolute Maximum Ratings

Symbol Parameter Value Unit

V

V

V

V

V

V

V

Ptot Power dissipation at Tamb=70°C0.45W

Tj 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-

Other pins ±2000 V

Figure 3. Pin Connection

Input voltage -0.3 to 6 V

6

Output switching voltage -1 to V

5

Shutdown -0.3 to V

1

Feedback voltage -0.3 to V

3

Error amplifier output voltage -0.3 to V

2

PGOOD -0.3 to V

8

Synchronization mode selector -0.3 to V

7

CC

±1000 V
AEC-Q100-002- “Human Body Model” Acceptance Criteria:
“Normal Performance’

CC

CC

CC

CC

CC

V

V

V

V

V

V

RUN

COMP

VFB

GND

1

2

3

4LX

D01IN1239AMOD

PGOOD8

SYNC

7

V

6

5

CC

Table 3. Thermal Data

Symbol Parameter Value Unit

R

th j-amb

Thermal Resistance Junction to Ambient for MSOP8 Max. 180 °C/W

Table 4. Pin Functions

N Name Description

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

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

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

4 GND Ground.

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

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

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

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

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

220pF capacitor is enough to guarantee the loop stability.

voltage by connecting this pin to an external resistor divider.

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

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.

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

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

(T

j

Symbol Parameter Test Condition Min Typ Max Unit

V

cc

V

cc ON

V

cc OFF

V

cc hys

R

p

R

n

I

lim

V

out

f

osc

f

sync

DC CHARACTERISTICS

I

q

I

sh

I

lx

ERROR AMPLIFIER CHARACTERISTICS

V

fb

I

fb

RUN

V

run_H

V

run_L

I

run

SYNC/MODE FUNCTION

V

sync_H

V

sync_L

PGOOD SECTION

V

PGOOD

∆V

PGOOD

V

Pgood(low)

I

LK-PGOOD

PROTECTIONS

HOVP Hard overvoltage threshold V

Note: 1. Guaranteed by design

2. Specification over the -40 to +125°C T

Operating input voltage After Turn on * 2 5.5 V

Turn On threshold 2.2 V

Turn Off threshold 2 V

Hysteresis 100 mV

High side Ron V

= 3.6V, I

cc

=100mA 240 300 mΩ

lx

* 400

Low side Ron V

= 3.6V, I

cc

=100mA 215 300 mΩ

lx

* 400

Peak current limit Vcc = 3.6V 1 1.2 1.5 A

*0.85 1.65

Valley current limit V

= 3.6V 1 1.4 1.7 A

cc

* 0.9 1.85

Output voltage range V

fb

Vcc V

Oscillator frequency 1.4 MHz

Sync mode clock

Quiescent current (low
noise mode)

Quiescent current (low
cunsumption mode)

(1)

V

= 0V, no load,

sync

V

> 0.6V

FB

V

= Vcc, no load,

sync

VFB > 0.6V

Shutdown current RUN to GND, V

LX leakage current

(1)

RUN to GND, V
V

= 5.5V

cc

RUN to GND, V
V

= 5.5V

cc

*2550µA

= 5.5V 0.2 µA

cc

= 5.5V,

LX

= 0V,

LX

12MHz

230 µA

1 µA

1 µA

Voltage feedback 0.593 0.600 0.607 V

(1)

Feedback input current

VFB = 0.6V 25 nA

RUN threshold high 1.3 V

RUN threshold low 0.4 V

RUN input current

(1)

25 nA

Sync mode threshold high 1.3 V

Sync mode threshold low 0.5 V

Power Good Threshold V

Power Good Hysteresis V

OUT

OUT

= V

= V

fb

fb

90 %Vout

4%Vout

Power Good Low Voltage Run to GND 0.4 V

Power Good Leakage
Current

(1)

V

temperature range are assured by design, characterization and statistical correlation.

j

= 3.6V 50 nA

PGOOD

OUT

= V

fb

10 %Vout

(2)

.

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