lm5085sdx National Semiconductor Corporation, lm5085sdx Datasheet - Page 3

• Manufacturer Part Number: lm5085sdx
• Description: 75v Constant On-time Pfet Buck Switching Controller
• Manufacturer: National Semiconductor Corporation

No.
Pin
Pin Descriptions
1
2
3
4
5
6
7
8
PGATE Gate Driver Output
Name
ISEN
GND
VCC
ADJ
VIN
RT
FB
EP
Description
Current Limit Adjust
On-time control and shutdown
Voltage Feedback from the
regulated output
Circuit Ground
Current sense input for current
limit detection.
Output of the gate driver bias
regulator
Input supply voltage
Exposed Pad
Application Information
The current limit threshold is set by an external resistor from VIN to ADJ in
conjunction with the external sense resistor or the PFET’s R
An external resistor from VIN to RT sets the buck switch on-time and switching
frequency. Grounding this pin shuts down the controller.
Input to the regulation and over-voltage comparators. The regulation level is
1.25V.
Ground reference for all internal circuitry
Connect to the PFET drain when using R
PFET source and the sense resistor when using a current sense resistor.
Connect to the gate of the external PFET.
Output of the negative voltage regulator (relative to VIN) that biases the PFET
gate driver. A low ESR capacitor is required from VIN to VCC, located as close
as possible to the pins.
The operating input range is from 4.5V to 75V. A low ESR bypass capacitor must
be located as close as possible to the VIN and GND pins.
Exposed pad on the underside of the package (MSOP-8EP and LLP only). This
pad is to be soldered to the PC board ground plane to aid in heat dissipation.
3
DS(ON)
current sense. Connect to the
DS(ON)
.
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