pip250m NXP Semiconductors, pip250m Datasheet - Page 6

• Manufacturer Part Number: pip250m
• Description: Pip250m Integrated Buck Converter
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 10904
Product data
7.2.5 Overcurrent protection
The overcurrent protection function is shown in
is enabled when the upper MOSFET gate drive signal is HIGH.
During this interval, the voltage on the PHASE input is compared with the voltage on
the OCSET/ENABLE input. If the voltage on the PHASE input is lower than the
voltage on the OCSET/ENABLE input, then the PIP250M detects an overcurrent trip
condition and turns off the gate drive to the upper MOSFET. There is an internal filter
with a time constant of 30 s in series with the PHASE input. Since the switching
frequency is 300 kHz, this means that the overcurrent trip operates if the overcurrent
condition persists for10 switching cycles.
If three overcurrent pulses are detected, the PIP250M latches off and produces no
more pulses until it has been reset. To reset the PIP250M, the supply voltage (V
must be reduced below the power down reset threshold and then increased back up
to 5 V.
An external resistor (R
overcurrent trip level (I
Fig 4. Overcurrent protection.
Rev. 02 — 21 February 2003
TRIP
OCSET
PHASE
) as a function of R
) sets the overcurrent trip level.
OCSET/
ENABLE
OC
strobe
CONTROL
R OCSET
LOGIC
1 nF
40 A
OCSET
PIP250M
Figure
.
V DDO
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
4. The overcurrent trip function
5 V
Integrated buck converter
03ak44
VO
Figure 5
PIP250M
shows the
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DDC
)