NCP81252
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4
Table 1. PIN DESCRIPTION
Pin Name Type Description
1 VRHOT# Logic Output VR HOT. Logic low output represents over temperature.
2 SDIO Logic Bidirectional Serial Data IO Port. Data port of SVID interface.
3 ALERT# Logic Output ALERT. Open−drain output. Provides a logic low valid alert signal of SVID interface.
4 SCLK Logic Input Serial Clock. Clock input of SVID interface.
5, 32, 49 GND Analog Ground Analog Ground. Ground of internal control circuits. Must be connected to the system ground.
6 VRRDY Logic Output Voltage Regulator Ready. Open−drain output. Provides a logic high valid power good
output signal, indicating the regulator’s output is in regulation window.
7,
11−17,
50
VIN Power Input Power Supply Input. These pins are the power supply input pins of the device, which are
connected to drain of internal high−side power MOSFET. 22 mF or more ceramic capacitors
must bypass this input to power ground. The capacitors should be placed as close as
possible to these pins.
8 BST Power Bidirectional
Bootstrap. Provides bootstrap voltage for the high−side gate driver. A 0.1 mF ~ 1 mF
ceramic capacitor is required from this pin to SW (pin10). A 1 ~ 2 W resistor may be
employed in series with the BST cap to reduce switching noise and ringing when needed.
9 GH Analog Output Gate of High−Side MOSFET. Directly connected with the gate of the high−side power
MOSFET.
10 SW Power Return Switching Node. Provides a return path for integrated high−side gate driver. It is internally
connected to source of high−side MOSFET.
18,
25−29,
51
SW Power Output Switch Node. Pins to be connected to an external inductor. These pins are interconnection
between internal high−side MOSFET and low−side MOSFET.
19−24 PGND Power Ground Power Ground. These pins are the power supply ground pins of the device, which are
connected to source of internal low−side power MOSFET. Must be connected to the system
ground.
30 GL Analog Output Gate of Low−Side MOSFET. Directly connected with the gate of the low−side power MOSFET.
31 VBOOT Analog Input Boot−Up Voltage. A resistor from this pin to ground programs SVID address.
33 VCCP Analog Power
Voltage Supply of Gate Driver. Power supply input pin of internal gate driver. A 4.7 mF or
larger ceramic capacitor bypasses this input to ground. This capacitor should be placed as
close as possible to this pin.
34 TSENSE Analog Temperature Sense. An external temperature sense network is connected to this pin.
35 IMAX Analog Input Current Maximum. A resistor from this pin to ground programs IMAX.
36 IOUT Analog Output OUT Current Monitor. Provides output signal representing output current by connecting a
resistor from this pin to ground. Shorting this pin to ground disables IMON function.
37 ILIM Analog Output Limit of Current. A resistor from this pin to CSCOMP programs over−current threshold with
inductor current sense.
38 CSCOMP Analog Output Current Sense COMP. Output pin of current sense amplifier.
39 CSSUM Analog Input Current Sense SUM. Inverting input of current sense amplifier.
40 CSREF Analog Input Current Sense Reference. Non−Inverting input of current sense amplifier.
41 FREQ Analog Input Frequency. A resistor from this pin to ground programs switching frequency.
42 COMP Analog Compensation. Output pin of error amplifier.
43 FB Analog Input Feedback. Inverting input to error amplifier.
44 DIFFOUT Analog Output Differential Amplifier Output. Output pin of differential voltage sense amplifier.
45 VSN Analog Input Voltage Sense Negative Input. Inverting input of differential voltage sense amplifier. It is
also used for DVID feed forward function with an external resistor.
46 VSP Analog Input Voltage Sense Positive Input. Non−inverting input of differential voltage sense amplifier.
47 VCC Analog Power
Voltage Supply of Controller. Power supply input pin of control circuits. A 1 mF or larger
ceramic capacitor bypasses this input to ground. This capacitor should be placed as close
as possible to this pin.
48 EN Logic Input Enable. Logic high enables the device and logic low makes the device in standby mode.
