LP38856_15 Datasheet, PDF (10/24 Pages) Texas Instruments – 3A Fast-Response High-Accuracy LDO Linear Regulator With Enable

LP38856
SNVS336F – JUNE 2006 – REVISED AUGUST 2015
7 Detailed Description
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7.1 Overview
The LP38556 is a fast-response, high-current, low-dropout regulator, available in output voltages 0.8 V and 1.2
V. This device is capable of delivering 3-A continuous load current. Standard regulator features, such as
overcurrent and overtemperature protection, are also included.
The LP38556 contains several features:
• Low dropout voltage, typical 240 mV at 3-A load.
• Low GND pin current, typical 10 mA at 3-A load.
• A shutdown feature is available, allowing the regulator to consume only 1 µA when EN pin is low.
7.2 Functional Block Diagram
IN
BIAS
LP38856-x.x
Under-Voltage
Lock-Out
Thermal
r_EN
Shut Down
OUT
EN
Enable
1.2V
V_REF
I_LIMIT
0.6V
GND
7.3 Feature Description
7.3.1 Enable Operation
The enable pin (EN) provides a mechanism to enable, or disable, the regulator output stage. The EN pin has an
internal pullup, through a typical 180-kΩ resistor, to V_BIAS.
If the EN pin is actively driven, pulling the EN pin above the V_EN threshold of 1.25 V (typical) will turn the
regulator output on, while pulling the EN pin below the V_EN threshold will turn the regulator output off. There is
approximately 100 mV of hysteresis built into the enable threshold provide noise immunity.
If the enable function is not needed, the EN pin must be left open, or connected directly to V_BIAS. If the EN pin is
left open, stray capacitance on this pin must be minimized, otherwise the output turnon will be delayed while the
stray capacitance is charged through the internal resistance (r_EN).
7.3.2 Input Voltage
The input voltage (V_IN) is the high current external voltage rail that will be regulated down to a lower voltage,
which is applied to the load. The input voltage must be at least V_OUT + V_DO, and no higher than whatever value is
used for V_BIAS.
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