MP2493 Datasheet, PDF (4/12 Pages) Monolithic Power Systems – 2A, 36V, Low EMI Step-Down Converter with Programmable Output Current Limit

MP2493 – 2A, 36V, LOW EMI STEP-DOWN WITH PROGRAMMABLE OUTPUT CURRENT LIMIT
PIN FUNCTIONS
Pin#
Name
1
VIN
2
GND
Exposed Pad
3
FB
4
SS
5
ISN
6
ISP
7
BST
8
SW
Description
Supply Voltage. The MP2493 operates from a +4.5V to +36V unregulated
input. C_IN is needed to prevent large voltage spikes from appearing at the
input. Put C_IN as close to the IC as possible. It is the drain of the internal
power device and power supply for the whole chip.
Ground. This pin is the voltage reference for the regulated output voltage.
For this reason care must be taken in its layout. This node should be placed
outside of the D1 to C_IN ground path to prevent switching current spikes from
inducing voltage noise into the part. Exposed Pad must be connected with
Ground pin in SOIC8E package.
Feedback. An external resistor divider from the output to GND, tapped to the
FB pin sets the output voltage. To prevent current limit run away during a
short circuit fault condition the frequency-fold-back comparator lowers the
oscillator frequency when the FB voltage is below 250mV.
Connect to an external capacitor used for Soft-Start and compensation for
current limiting loop.
Negative Current Sense Input for load current limiting.
Positive Current Sense
Bootstrap. This capacitor is needed to drive the power switch’s gate above
the supply voltage. It is connected between SW and BST pins to form a
floating supply across the power switch driver. An on-chip regulator is used
to charge up the external boot-strap capacitor. If the on-chip regulator is not
strong enough, one optional diode can be connected from IN or OUT to
charge the external boot-strap capacitor.
Switch Output. It is the source of power device.
MP2493 Rev. 0.9
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4
4/23/2010
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