lm2638m National Semiconductor Corporation, lm2638m Datasheet - Page 5

• Manufacturer Part Number: lm2638m
• Description: Motherboard Power Supply Solution With A 5-bit Programmable Switching Controller And Two Linear Regulator Controllers
• Manufacturer: National Semiconductor Corporation

Pin Description
Pin
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1
2
3
4
5
6
7
8
9
LG
PGND
V
SNS2
G2
SGND
V
SNS1
CS+
CS−
CP
FREQ
EAO
FB
PWGD
VID4
VID3
VID2
VID1
VID0
G3
SNS3
EN
HG
DD
CC
Pin Name
Low side N-FET gate driver output.
Ground for the two FET drivers of the switching section.
Supply for the FET gate drivers. Usually tied to +12V.
Feedback pin for the 1.5V linear regulator.
Gate drive output for the external N-MOS of the fast 1.5V linear regulator.
Ground for internal signal circuitry and system ground reference.
Supply voltage. Usually +5V.
Output voltage monitor input for the switching regulator.
Switching regulator current sense input, positive node.
Switching regulator current sense input, negative node.
Charge pump. Output is a square wave with 50% duty cycle. Amplitude is close to V
voltage.
Switching frequency adjustment pin. An external resistor is needed to set the desired
frequency.
Output of the error amplifier. Used for compensating the switching regulator.
Inverting input of the error amplifier. Used for compensating the switching regulator.
Open collector Power Good signal.
5-Bit DAC input, MSB.
5-Bit DAC input.
5-Bit DAC input.
5-Bit DAC input.
5-Bit DAC input, LSB.
Gate drive pin for the external N-MOS of the 1.25V linear regulator.
Feedback pin for the 1.25V linear regulator.
Output Enable. A logic low shuts the whole chip down.
High side N-FET gate driver output.
5
Pin Function
www.national.com
CC