ADP1111AN-33 Analog Devices, ADP1111AN-33 Datasheet - Page 13

• Manufacturer Part Number: ADP1111AN-33
• Description: Micropower/ Step-Up/Step-Down SW Regulator; Adjustable and Fixed 3.3 V/ 5 V/ 12 V
• Manufacturer: Analog Devices

The circuit of Figure 27b may produce multiple pulses when
approaching the trip point due to noise coupled into the SET
input. To prevent multiple interrupts to the digital logic,
hysteresis can be added to the circuit (Figure 27). Resistor
RHYS, with a value of 1 M to 10 M , provides the hysteresis.
The addition of RHYS will change the trip point slightly, so the
new value for R1 will be:
where V
resistor, and R
APPLICATION CIRCUITS
All Surface Mount 3 V to 5 V Step-Up Converter
This is the most basic application (along with the basic step-
down configuration to follow) of the ADP1111. It takes full
advantage of surface mount packaging for all the devices used in
the design. The circuit can provide +5 V at 100 mA of output
current and can be operated off of battery power for use in
portable equipment.
Figure 28. All Surface Mount +3 V to +5 V Step-Up Converter
REV. 0
INPUT +3V
(OPTIONAL)
V
L
BAT
is the logic power supply voltage, R
NC
AO
R3*
ADP1111-5
6
33k
HYS
I
1
LIM
SET
NC
7
R1
R1
R2
creates the hysteresis.
V
2
GND
IN
5
1.25V
SET
1.25 V
SENSE
SW2
REF
SW1
4
R2
CTX20-4
V
Figure 27b.
20µH
L1
LOBATT
ADP1111
3
8
GND
V
IN
MBRS120T3
1.6M
R
V
R
HYS
AO
L
L
D1
1.25 V
5V
1.25 V
R
R
47k
HYS
L
L
+
is the pull-up
TO
PROCESSOR
C
33µF
L
OUTPUT
(5V @ 100mA)
–13–
9 V to 5 V Step-Down Converter
This circuit uses a 9 V battery to generate a +5 V output. The
circuit will work down to 6.5 V, supplying 50 mA at this lower
limit. Switch current is limited to around 500 mA by the 100
resistor.
20 V to 5 V Step-Down Converter
This circuit is similar to Figure 29, except it supplies much
higher output current and operates over a much wider range of
input voltage. As in the previous examples, switch current is
limited to 500 mA.
+5 V to –5 V Converter
This circuit is essentially identical to Figure 22, except it uses a
fixed-output version of the ADP1111 to simplify the design
somewhat.
INPUT
12V TO 28V
12V TO 28V
9V
INPUT
Figure 30. 20 V to 5 V Step-Down Converter
Figure 29. 9 V to 5 V Step-Down Converter
INPUT
100
R
LIM
Figure 31. +5 V to –5 V Converter
ADP1111-5
I
AO
NC
LIM
1
6
100
R
LIM
100
R
SET
ADP1111-5
AO
V
I
NC
NC
LIM
1
LIM
6
2
7
IN
ADP1111-5
AO
NC
I
LIM
1
6
GND
SET
SW1
V
NC
SENSE
2
7
3
5
IN
SET
SW2
V
NC
2
7
IN
GND
SW1
SENSE
3
5
GND
SW2
SW1
4
8
SENSE
3
5
SW2
CTX15-4
4
8
15µH
D1
1N5818
L1
4
8
CTX68-4
68µH
D1
1N5818
L1
CTX33-2
33µH
+
D1
1N5818
L1
C
22µF
+
L
ADP1111
OUTPUT
(9V
6.5V
+
C
47µF
IN
IN
L
TO 5V @ 150mA,
OUTPUT
(+5V @ 300mA)
C
33µF
TO 5V @ 50mA)
L
–5V
@ 75mA