Micrel, Inc.
LM2575
Functional Characteristics
(circuit of
Figure 1)
Load Transient Response
Switching Waveforms
Output
Voltage
Change
+100mV
0
–100mV
A
10V
0
B
1A
0
C
1A
.5A
1.0A
Output
Current
0.5A
0
V
OUT
= 5V
100µs/div.
D
0
V
OUT = 5V
V
IN = 20V
A: Output pin voltage 10V/div
B: Output pin current 1A/div
C: Inductor current 0.5A/div
D: Output ripple voltage 20 mV/div. AC coupled
Horizontal Time Base: 5µs/div
Functional Diagrams
V IN
1
4
3.1k
FIXED GAIN
ERROR AMP
INTERNAL
REGULATOR
ON/OFF
5
ON/OFF
FB
+
1.0k
COMPARATOR
1 AMP
SWITCH
DRIVER
-
+
-
2
THERMAL
SHUTDOWN
CURRENT
LIMIT
OUT
1.23V
BAND-GAP
REFERENCE
52 kHz
OSCILLATOR
RESET
3
GND
Note: Pin numbers are for the TO-220 package
Fixed Regulator
VIN
1
FIXED GAIN
ERROR AMP
INTERNAL
REGULATOR
ON/OFF
5
ON/OFF
FB
4
+
-
+
-
COMPARATOR
1 AMP
SWITCH
DRIVER
2
THERMAL
SHUTDOWN
CURRENT
LIMIT
OUT
1.23V
BAND-GAP
REFERENCE
52 kHz
OSCILLATOR
RESET
3
GND
Adjustable Regulator
May 2009
9
M9999-051209-B
MICREL [ MICREL SEMICONDUCTOR ]
