Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - DC/DC voltage regulator Switched-capacitor voltage converter VSSOP 10

 

 

SLVS391B − OCTOBER 2001 − REVISED FEBRUARY 2002

www.ti.com

DESIGN PROCEDURE

capacitor selection

Designed specifically for space-critical battery-powered applications, the complete converter requires only four

external capacitors. The capacitor values are closely linked to the required output current, output noise, and

ripple requirements. The input capacitor improves system efficiency by reducing the input impedance, and it

also stabilizes the input current. The value of the output capacitor, C

, influences the stability of the voltage

regulator. The minimum required capacitance for C

is 4.7 µF. Depending on the maximum allowed output ripple

voltage and load current, larger values can be chosen. For an output current greater than 150 mA, a minimum

output capacitor of 22 µF is required. Table 1 shows ceramic capacitor values recommended for low output

voltage ripple.

Table 1. Recommended Capacitors

MANUFACTURER PART NUMBER SIZE CAPACITANCE TYPE

Taiyo Yuden

LMK212BJ105KG

LMK212BJ225MG

EMK316BJ225KL

LMK316BJ475KL

JMK316BJ106KL

0805

1206

1 µF

2.2 µF

4.7 µF

10 µF

Ceramic

TDK

C2012X5R1C105M

C2012X5R1A225M

C2012X5R0J106M

0805

1 µF

2.2 µF

10 µF/6.3 V

Ceramic

Table 2 contains a list of manufacturers of ceramic capacitors. Ceramic capacitors provide the lowest output

voltage ripple because they typically have the lowest ESR-rating.

Table 2. Recommended Capacitor Manufacturers

MANUFACTURER CAPACITOR TYPE INTERNET

Taiyo Yuden X7R/X5R ceramic www.t−yuden.com

TDK X7R/X5R ceramic www.component.tdk.com

Vishay X7R/X5R ceramic www.vishay.com

Kemet X7R/X5R ceramic www.kemet.com

APPLICATION INFORMATION

typical application circuit for fixed voltage and adjustable voltage versions

Figure 26 shows the typical operation circuit. The TPS60501 to TPS60503 devices use an internal resistor

divider for sensing the output voltage. The FB pin must be connected externally with the output. For maximum

output current and best performance, 4 ceramic capacitors are recommended. For lower currents or higher

allowed output voltage ripple, other capacitors can also be used. It is recommended that the output capacitor

has a minimum value of 4.7 µF. This value is necessary to maintain a stable operation of the system. Flying

capacitors lower than 1 µF can be used, but this decreases the maximum output power. This means that the

device works in linear mode with lower output currents. The device works in the linear mode for an output current

of greater than 150 mA. With an output current greater than 150 mA, an output capacitor of ≥22 µF must be used.

Figure 26 shows that two 10-µF capacitors can also be used in parallel.