TPS78227

GND

EN

IN

OUT

V

IN

V

OUT

1 F

m

1 F

m

4.2Vto5.5V

2.7V

t=3

10k

R

W

L

´

C

OUT

´

TPS782

www.ti.com

SBVS115D – AUGUST 2008 – REVISED JANUARY 2015

Feature Description (continued)

7.3.3 Shutdown

The enable pin (EN) is active high and is compatible with standard and low-voltage CMOS levels. When

shutdown capability is not required, EN should be connected to the IN pin, as shown in Figure 22. The TPS782

shown in Equation 1:

(1)

Where:

Figure 22. Circuit Showing EN Tied High When Shutdown Capability Is Not Required

7.4 Device Functional Modes

Table 1 provides a quick comparison between the normal, dropout, and disabled modes of operation.

Table 1. Device Functional Mode Comparison

PARAMETER

OPERATING MODE

EN

Normal

Dropout

Disabled

—

—

7.4.1 Normal Operation

The device regulates to the nominal output voltage under the following conditions:

•

•

The enable voltage has previously exceeded the enable rising threshold voltage and not yet decreased below

the enable falling threshold.

•

•

7.4.2 Dropout Operation

If the input voltage is lower than the nominal output voltage plus the specified dropout voltage, but all other

conditions are met for normal operation, the device operates in dropout mode. In this mode, the output voltage

tracks the input voltage. During this mode, the transient performance of the device becomes significantly

degraded because the pass device is in a triode state and no longer controls the current through the LDO. Line

or load transients in dropout can result in large output-voltage deviations.

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