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LM2638 Datasheet(PDF) 3 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor.
Part # LM2638
Description  Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator Controllers
PDF  8 Pages
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Manufacturer  NSC [National Semiconductor (TI)]
Direct Link  http://www.national.com
Logo NSC - National Semiconductor (TI)

LM2638 Datasheet(HTML) 3 Page - National Semiconductor (TI)

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Electrical Characteristics V
CC = 5V, VDD = 12V unless otherwise specified. Typicals and limits appearing in
plain type apply for T
A = TJ = +25˚C. Limits appearing in boldface type apply over the 0˚C to +70˚C range. (Continued)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
SWITCHING SECTION
V
PWGD_HI
PWGD High Trip Point
% Above Rated Output Voltage
When Output Voltage
↑
11.5
13
%
% Above Rated Output Voltage
When Output Voltage
↓ (Note
4)
5
7
9
V
PWGD_LO
PWGD Low Trip Point
% Below Rated Output Voltage
When Output Voltage
↑
2.6
6
%
% Below Rated Output Voltage
When Output Voltage
↓ (Note
4)
6
9.5
13
V
OVP_TRP
Over-Voltage Trip Point
% SNS1 Above Rated Output
15
25
35
%
I
CS+
CS+ Pin Sink Current
CS+ = 5V, CS− = 4.8V
126
185
244
µA
V
OCP
Over-Current Trip Point (CS+
and CS− Differential Voltage)
CS+ = 2V, CS− Drops from 2V
41
55
69
mV
1.5V LDO CONTROLLER SECTION
V
SNS2
SNS2 Voltage
V
DD = 12V, VCC = 4.75V to
5.25V, I
G2 = 0mAto20mA
1.463
1.5
1.538
V
R
OUT2
Output Resistance
200
Ω
I
SNS2
SNS2 Pin Bias Current
When Regulating
21
µA
V
PWGD_HI
PWGD High Trip Point
(Note 4)
0.63
V
V
PWGD_LO
PWGD Low Trip Point
(Note 4)
0.44
V
1.25V LDO CONTROLLER SECTION
V
SNS3
SNS3 Voltage
V
DD = 12V, VCC = 4.75V to
5.25V, I
G3 = 0mAto20mA
1.219
1.25
1.281
V
R
OUT3
Output Resistance
200
Ω
I
SNS3
SNS3 Pin Bias Current
When Regulating
0
µA
V
PWGD_HI
PWGD High Trip Point
(Note 4)
0.63
V
V
PWGD_LO
PWGD Low Trip Point
(Note 4)
0.44
V
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating ratings are conditions under which the device operates
correctly. Operating Ratings do not imply guaranteed performance limits.
Note 2: Maximum allowable power dissipation is a function of the maximum junction temperature, TJMAX, the junction-to-ambient thermal resistance, θJA, and the
ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: PMAX = (TJMAX −TA)/θJA. The
junction-to-ambient thermal resistance,
θJA, for LM2638 is 78˚C/W. For a TJMAX of 150˚C and TA of 25˚C, the maximum allowable power dissipation is 1.6W.
Note 3: The letter
N stands for the typical output voltages appearing in italic boldface type in Table 1.
Note 4: The output level of the PWGD pin is a logic AND of the power good function of the switching section, the 1.5V section and the 1.25V section. For the switch-
ing section, the power good is a window. For the two linear sections, the power good is a threshold with some hysteresis.
www.national.com
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