1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATOR
SLVS569E – JANUARY 2005 – REVISED JANUARY 2006
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FUNCTIONAL BLOCK DIAGRAM
V
IN
6
+
C
IN
Unregulated
DC Input
Internal
Regulator
ON/OFF
ON/OFF
9
FEEDBACK
7
R2
Fixed-Gain
Error Amp
+
_
R1
Comparator
+
_
Driver
1-A
Switch
OUTPUT
3
D1
L1
+
C
OUT
L
O
A
D
V
OUT
1.23-V
Band-Gap
Reference
GND
52-kHz
Oscillator
Reset
Thermal
Shutdown
Current
Limit
5, 12, 13
R1 = Open, R2 = 0
Ω
Absolute Maximum Ratings
(1)
over operating free-air temperature range (unless otherwise noted)
MIN
V
IN
Supply voltage
ON/OFF pin input voltage
Output voltage to GND (steady state)
T
J
T
stg
(1)
Maximum junction temperature
Storage temperature range
–65
–0.3
MAX
42
V
IN
–1
150
150
UNIT
V
V
V
°C
°C
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating
conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Package Thermal Data
(1)
PACKAGE
PDIP (N)
(1)
BOARD
High K, JESD 51-7
θ
JC
51°C/W
θ
JA
67°C/W
Maximum power dissipation is a function of T
J
(max),
θ
JA
, and T
A
. The maximum allowable power dissipation at any allowable ambient
temperature is P
D
= (T
J
(max) – T
A
)/θ
JA
. Operating at the absolute maximum T
J
of 150°C can affect reliability.
Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
V
IN
T
J
Supply voltage
Operating virtual junction temperature
4.75
–40
MAX
40
125
UNIT
V
°C
2
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