ST L6925D User Manual
L6925D
Fi
HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS
STEP DOWN REGULATOR
1FEATURES
■ 2.7V TO 5.5V BATTERY INPUT RANGE
■ HIGH EFFICIENCY: UP TO 95%
■ INTERNAL SYNCHRONOUS SWITCH
■ NO EXTERNAL SCHOTTKY REQUIRED
■ EXTREMELY LOW QUIESCENT CURRENT
■ 800mA MAX OUTPUT CURRENT
■
ADJUSTABL E OUTPUT VOLTAGE FRO M 0.6V
■ LOW DROP-OUT OPERATION: UP TO100%
DUTY CYCLE
■ SELECTABLE LOW NOISE/LOW
CONSUMPTION MODE AT LIGHT LOAD
■ LOW BATTERY INPUT
■ LOW BATTERY OUTPUT
■ ±1% OUTPUT VOLTAGE ACCURACY
■ CURRENT-MODE CONTROL
■ 600kHz SWITCHING FREQUENCY
■ EXTERNALLY SYNCHRONIZABLE FROM
500kHz TO 1.4MHz
■ OVP
■ SHORT CIRCUIT PROTECTION
1.1 APPLICATIONS
■ BATTERY-POWERED EQUIPMENTS
■ PORTABLE INSTRUMENTS
■ CELLULAR PHONES
■ PDAs AND HAND HELD TERMINALS
■ DSC
■ GPS
gure 1. Package
MSOP8
Table 1. Orde r Codes
Part Number Package
L6925D MSOP8 (Tube)
L6925D013TR Tape & Reel
2DESCRIPTION
The device is dc-dc monolithic regulator specifically
designed to provide extremely high efficiency.
The device has on UVLO set at 2.7V cause it is particurarly thought for single Li-ion cell applications.
Output voltage can be selected by an exter nal divider
down to 0.6V. Duty Cycle can saturate to 100% allowing low drop-out operation.
The device is based on a 600kHz fixed-frequency,
current mode-architecture. Low Consumption Mode
operation can be selected at light load conditions, allowing switching losses to be reduced. L6925D is externally synchronizable with a clock which makes it
useful in noise-sensitive applications.
LBI pin can be used to have a LBO
Battery voltage is lower than a preset value. Other
features like, Overvoltage protection, Shortcircuit
protection and Thermal Shutdown (150°C) are also
present.
signal when the
Figure 2. Applica t i on Test Circuit
V
=2.7V to 5.5V
IN
C1
10µF
6.3V
September 2004
R2
600K
R1
100K
D01IN1238B
SYNC
7
V
CC
6
LBI
1
8
LBO
24
COMP GND
220pF
C2
L 6.8µH
5
LX
VFB
3
R4
200K
R3
100K
V
=1.8V
OUT
C4
10µF
6.3V
Rev. 3
1/6
L6925D
Table 2. Absolute Maximum Ratings
Symbol Parameter Value Unit
V
V
V
1, V8
V
V
V
P
tot
T
T
stg
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
Low Battery Input, Low Battery Output -0.3 to V
Feedback voltage -0.3 to V
3
Error Amplifier Output Voltage -0.3 to V
2
Syncronization / Mode Selector -0.3 to V
7
CC
CC
CC
CC
CC
Power dissipation at Tamb=70°C0.45W
Junction operating temperature range -40 to 150 °C
j
Storage temperature range -65 to 150 °C
±1000 V
AEC-Q100-002- “Human Body Model” Acceptance Criteria:
“Normal Performance’
V
V
V
V
V
LBI
COMP
VFB
GND
1
2
3
4LX
D01IN1239A/mod
7
6
5
LBO8
SYNC
V
CC
Table 3. Thermal Data
Symbol Parameter Value Unit
R
th j-amb
Thermal Resistance Junction to Ambient 180 °C/W
Table 4. Pin Functions
N Name Description
1 LBI Battery low voltage detector input. The internal threshold is set to 0.6V. The external threshold
can be adjusted by using an external resistor divider.
2 COMP Error amplifier output. Compensate it with a 220pF capacitor
3 VFB Error amplifier input. The output voltage can be adjusted by using an external resistor divider
connected to this pin (V
4 GND Ground.
= 0.6V).
FB
5 LX Switch node connection to the inductor.
6 VCC Input voltage.
7 SYNC This pin allows to select Low Noise/ Low Consumption Mode or to sychronize the device.
8LBO
Battery low voltage detector output. If the voltage at the LBI pin drops below the internal
thrshold, LBO
goes low. The LBO is an open drain output. A pull_up resistor should be
connected between the pin and the output voltage
2/6
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