LP38856_15 Datasheet, PDF (12/24 Pages) Texas Instruments – 3A Fast-Response High-Accuracy LDO Linear Regulator With Enable

LP38856
SNVS336F – JUNE 2006 – REVISED AUGUST 2015
8 Application and Implementation
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NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LP38856 can provide 3-A output current with 240-mV dropout voltage (typical). The bias voltage must be in
the range of 3 V to 5.5 V to ensure proper operation of the device. The input voltage must be at least V_OUT +
V_DO, and no higher than whatever value is used for V_BIAS. Minimal input and output capacitor are 10 µF. The
capacitor on the bias pin must be at least 1 μF.
8.2 Typical Application
V_IN
V_BIAS
V_EN
GND
LP38856-x.x
C_IN
10 PF Ceramic
C_BIAS
1 PF
IN
BIAS
EN
OUT
GND
V_OUT
C_OUT
10 PF
Ceramic
GND
Figure 23. LP38856 Typical Application
8.2.1 Design Requirements
For LP38856 typical applications, use the parameters listed in Table 1 as the input parameters.
DESIGN PARAMETERS
Bias voltage
Input voltage
Output voltage
Output current
Bias capacitor
Input capacitor
Output capacitor
Table 1. Design Parameters
VALUE
3 V to 5.5 V
V_OUT+0.3 V to V_BIAS
0.8 V or 1.2 V
3 A (maximum)
1 µF (minimum)
10 µF (minimum)
10 uF (minimum)
8.2.2 Detailed Design Procedure
8.2.2.1 External Capacitors
To assure regulator stability, capacitors are required on the IN, OUT, and BIAS pins as shown in Figure 23.
8.2.2.1.1 Output Capacitor
A minimum output capacitance of 10 µF, ceramic, is required for stability. The amount of output capacitance can
be increased without limit. The output capacitor must be located less than 1 cm from the output pin of the device
and returned to the device ground pin with a clean analog ground.
Only high quality ceramic types such as X5R or X7R should be used, as the Z5U and Y5F types do not provide
sufficient capacitance over temperature.
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