Datasheet

13
LT1020
sn1020 1020fcs
TYPICAL APPLICATIO S
U
50mA Battery Charger and Regulator
1020 TA21
6
1M
51k
V
OUT
0.001µF
+
4
7
8
9
1M
10µF
2
11
FB
5V
V
IN
*
3
–
+
LT1020
2.5V
20k
V
IN
220k
+
10µF
+
10µF
6V
BATTERY
2N2905
*V
IN
MUST BE GREATER THAN THE
BATTERY VOLTAGE PLUS 1.3V
3.9Ω
10µF
+
Charge Pump Voltage Doubler
–
+
1020 TA20
5
6
7
8
9
22k
51k
V
IN
3
V
OUT
1M
2N3904
10µF
V
OUT
(NL) ≅ 2V
IN
– 1V
V
OUT
(5mA) ≅ 2V
IN
– 3V
I
Q
≅ 300µA
0.0033µF
51k
1M
20µF
1N5819
OR EQUIVALENT
+
+
Switching Preregulator for Wide Input Voltage Range
–
+
+
22µF
0.01µF
POST REGULATOR
2
11
3
4
V
IN
V
OUT
FB
V
OUT
5V
100mA
LT1020
1020 TA22
MAINTAINS LOW I
Q
(< 100µA)
FOR ALL INPUT VOLTAGES
SWITCHER EFFICIENCY = 85%
POST REGULATOR EFFICIENCY = 82%
OVERALL EFFICIENCY = 70%
SWITCHING REGULATOR OUTPUT =
2.5 × (1 + R
A
/R
B
). FOR A CLEAN OUTPUT
FROM THE LINEAR REGULATOR SET TO V
OUT
+ 1.2V
V
REF
220k
+
100µF
LT1020
COMPARATOR
V
IN
7.5V TO 30V
TO
V
REF
(PIN4)
100µF
1.8M
1M
3.3M
30k
1k
2N3906
100k
10k
2M
R
B
1M
2M
30k
R
A
1.5M
0.001µF
SWITCHING
REGULATOR
OUTPUT
4mH
30k
220k
8
7
2N3904
2N3904
2N2222
6