TPS22934

VIN

VOUT

ON

GND

CIN1

GND

VREG1=1.8V

CIN2

VREG2=2.8V

GND

GND

1.8V Supply

2.8V Supply

Processor/

Subsystem

Li-ion

Battery

TPS22934

SLVSAD4B – AUGUST 2010 – REVISED APRIL 2015

www.ti.com

9.2 Typical Application

Figure 30 demonstrates how the TPS22934 can be used for power-rail sequencing.

Figure 30. 1.8-V and 2.8-V Power-Rail Sequencing

9.2.1 Design Requirements

Table 4. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

VREG1

1.8 V

VREG2

2.8 V

9.2.2 Detailed Design Procedure

9.2.2.1 Input Capacitor

To limit the voltage drop on the input supply caused by transient in-rush currents when the switch turns on into a

discharged load capacitor or short-circuit, a capacitor must be placed between VIN and GND. A 1-µF ceramic

capacitor, CIN, placed close to the pins is usually sufficient. Higher values of CIN can be used to further reduce

the voltage drop. A CIN to CL ratio of 10 to 1 is recommended.

9.2.2.2 Output Capacitor

Due to the integral body diode in the PMOS switch, TI highly recommends a CIN greater than CL. A CL greater

than CIN can cause VOUT to exceed VIN when the system supply is removed. This could result in current flow

through the body diode from VOUT to VIN.

16

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