TPS60111

REGULATED 5V 150mA LOW NOISE

CHARGE PUMP DC/DC CONVERTER

SLVS216B − JUNE 1999 − JUNE 2008

10

POST OFFICE BOX 655303

detailed description

operating principle

The TPS60111 charge pump provides a regulated 5-V output from a 2.7-V to 5.4-V input. It delivers a maximum

load current of 150 mA. Designed specifically for space critical battery powered applications, the complete

charge pump circuit requires only four external capacitors. The circuit can be optimized for highest efficiency

at light loads or lowest output noise. The TPS60111 consists of an oscillator, a 1.22-V bandgap reference, an

internal resistive feedback circuit, an error amplifier, high current MOSFET switches, a shutdown/start-up

circuit, and a control circuit (Figure 25).

C1+

C1−

ENABLE

OUT

FB

0

°

180

°

PGND

C1F

IN

CHARGE PUMP 2

C2+

C2−

OUT

PGND

C2F

IN

T22

T21

OSCILLATOR

GND

SKIP

COM

CLK

VREF −+

−

+

CONTROL

CIRCUIT

0.8

× VIN

−

+

−

+

SHUTDOWN/

START-UP

CONTROL

SYNC

T11

T12

T13

T14

T24

T23

CHARGE PUMP 1

Figure 25. Functional Block Diagram TPS60111

The oscillator runs at a 50% duty cycle. The device consists of two single-ended charge pumps which operate

with 180

transfer phase. This operation guarantees an almost constant output current which ensures a low output ripple.

If the clock were to run continuously, this process would eventually generate an output voltage equal to two times

the input voltage (hence the name doubler). In order to provide a regulated fixed output voltage of 5 V, the

TPS60111 uses either pulse-skip mode or constant-frequency mode. Pulse-skip mode and constant-frequency

mode are externally selected via the SKIP input pin.