IP1203PBF datasheet(10/23 Pages) IRF

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iP1203PbF

The operating switching frequency (f

SW) range of

iP1203PbF is 200 kHz to 400 kHz. The desired fre-

quency is set by placing an external resistor to the

RT pin of the iP1203PbF. See Fig. 9 for the proper

resistor value.

The iP1203PbF is capable of accepting an external

digital synchronization signal. Synchronization will

be enabled by the rising edge clock. The free run-

ning oscillator frequency is twice the switching fre-

quency. During synchronization, RT is selected such

that the free running frequency is 20% below the

synchronization frequency. The maximum synchro-

nization frequency that iP1203PbF can accept is

800kHz. Note that the actual switching frequency is

half the synchronization frequency.

iP1203PbF Users Design Guidelines

The iP1203PbF is a single output 15A power block

consisting of optimized power semiconductors, PWM

control and its associated passive components. It is

based on a synchronous buck topology and offers

an optimized solution where space, efficiency and

noise caused by parasitics are of concern. The power

block operates with fixed frequency voltage mode

control. The iP1203PbF components are integrated

in a land grid array (LGA) package.

IN / Enabling the Output

The input operating voltage range of the iP1203PbF

is 5.5V to 13.2V.

The iP1203PbF output is turned on upon application

of input voltage. The V

IN slew rate should not exceed

50mV/µs. The converter can also be turned on and

off by releasing or pulling the SS pin low through a

logic level MOSFET, the drain of which connects to

the soft start pin (see Fig.12). This feature can be

useful if sequencing or different start-up timing of dif-

ferent system outputs are required. In situations where

the output has undergone a latched shutdown due to

overvoltage, cycling Vin will reset the output. Cycling

soft start pin will not unlatch the output.

Soft Start

The Soft Start function provides a controlled rise of

the output voltage, thus limiting the inrush current.

The soft start function has an internal 25µA +/-20%

current source that charges the external soft start

capacitor Css up to 3V. During power-up, the output

voltage starts ramping up only after the charging volt-

age across the Css capacitor has reached a 0.8Vtyp

threshold, as shown in Fig. 13.

Fig. 13: Power Up Threshold

0.8Vtyp

VCss

VOUT

Fig.12: Soft Start/Enable Circuit

Frequency and Synchronization

Css

Iss

iP1203

iP1203PbF

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