ST L6925D User Manual
L6925D
HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS STEP DOWN REGULATOR
1 FEATURES
■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
■ADJUSTABLE OUTPUT VOLTAGE FROM 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
Figure 2. Application Test Circuit
Figure 1. Package
MSOP8 |
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Table 1. Order Codes |
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Part Number |
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Package |
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L6925D |
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MSOP8 (Tube) |
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L6925D013TR |
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Tape & Reel |
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2 DESCRIPTION
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 external 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 signal when the Battery voltage is lower than a preset value. Other features like, Overvoltage protection, Shortcircuit protection and Thermal Shutdown (150°C) are also present.
VIN=2.7V to 5.5V |
SYNC |
7 |
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L 6.8 H |
VOUT=1.8V |
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VCC |
5 |
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C1 |
6 |
LX |
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R2 |
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10 F |
600K |
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R4 |
C4 |
6.3V |
LBI |
1 |
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200K |
10 F |
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6.3V |
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VFB |
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R1 |
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3 |
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8 |
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100K LBO |
4 |
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2 |
R3 |
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COMP |
GND |
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100K |
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C2 |
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D01IN1238B |
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220pF |
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Rev. 3 |
September 2004 |
1/6 |
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L6925D
Table 2. Absolute Maximum Ratings
Symbol |
Parameter |
Value |
Unit |
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V6 |
Input voltage |
-0.3 to 6 |
V |
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V5 |
Output switching voltage |
-1 to VCC |
V |
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V1, V8 |
Low Battery Input, Low Battery Output |
-0.3 to VCC |
V |
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V3 |
Feedback voltage |
-0.3 to VCC |
V |
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V2 |
Error Amplifier Output Voltage |
-0.3 to VCC |
V |
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V7 |
Syncronization / Mode Selector |
-0.3 to VCC |
V |
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Ptot |
Power dissipation at Tamb=70°C |
0.45 |
W |
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Tj |
Junction operating temperature range |
-40 to 150 |
°C |
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Tstg |
Storage temperature range |
-65 to 150 |
°C |
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LX Pin |
Maximum Withstanding Voltage Range Test Condition: CDF- |
±1000 |
V |
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AEC-Q100-002- “Human Body Model” Acceptance Criteria: |
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Other pins |
±2000 |
V |
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“Normal Performance’ |
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Figure 3. Pin Connection |
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LBI |
1 |
8 |
LBO |
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COMP |
2 |
7 |
SYNC |
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VFB |
3 |
6 |
VCC |
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GND |
4 |
5 |
LX |
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D01IN1239A/mod |
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Table 3. Thermal Data |
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Symbol |
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Parameter |
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Value |
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Unit |
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Rth j-amb |
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Thermal Resistance Junction to Ambient |
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180 |
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°C/W |
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Table 4. Pin Functions |
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Name |
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Description |
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1 |
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LBI |
Battery low voltage detector input. The internal threshold is set to 0.6V. The external threshold |
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can be adjusted by using an external resistor divider. |
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2 |
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COMP |
Error amplifier output. Compensate it with a 220pF capacitor |
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3 |
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VFB |
Error amplifier input. The output voltage can be adjusted by using an external resistor divider |
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connected to this pin (VFB = 0.6V). |
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4 |
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GND |
Ground. |
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5 |
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LX |
Switch node connection to the inductor. |
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6 |
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VCC |
Input voltage. |
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7 |
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SYNC |
This pin allows to select Low Noise/ Low Consumption Mode or to sychronize the device. |
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8 |
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Battery low voltage detector output. If the voltage at the LBI pin drops below the internal |
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LBO |
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thrshold, LBO goes low. The LBO is an open drain output. A pull_up resistor should be |
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connected between the pin and the output voltage |
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