Datasheet

Data Sheet ADP2116
Rev. A | Page 23 of 36
CONVERTER CONFIGURATION
SELECTING THE OUTPUT VOLTAGE
To set the output voltage, V
OUT1
or V
OUT2
, select one of the six
fixed voltages, as shown in Table 4, by connecting the V1SET or
V2SET pin to GND through a resistor of an appropriate value
(see Figure 62). V1SET and V2SET set the voltage output levels
for Channel 1 and Channel 2, respectively. The feedback pin,
FB1 or FB2, should be directly connected to V
OUT1
or V
OUT2
.
Table 4. Output Voltage Programming
R
V1SET
± 5% V
OUT1
(V) R
V2SET
± 5% V
OUT2
(V)
0 Ω to GND 0.8 0 Ω to GND 0.8
4.7 kΩ to GND 1.2 4.7 kΩ to GND 1.2
8.2 kΩ to GND 1.5 8.2 kΩ to GND 1.5
15 kΩ to GND 1.8 15 kΩ to GND 1.8
27 kΩ to GND 2.5 27 kΩ to GND 2.5
47 kΩ to GND 3.3 47 kΩ to GND 3.3
82 kΩ to GND 0.6 to <1.6
(adjustable)
82 kΩ to GND 0.6 to <1.6
(adjustable)
0 Ω to VDD 1.6 to 3.3
(adjustable)
0 Ω to VDD 1.6 to 3.3
(adjustable)
If the required output voltage, V
OUT1
or V
OUT2
, is in the adjustable
range, from 0.6 V to <1.6 V, connect V1SET or V2SET through
an 82 kΩ resistor to GND. For the adjustable output voltage range
of 1.6 V to 3.3 V, tie V1SET or V2SET to VDD (see Table 4). The
adjustable output voltage of the ADP2116 is externally set by a
resistive voltage divider from the output voltage to the feedback
pin (see Figure 63). The ratio of the resistive voltage divider sets
the output voltage, whereas the absolute value of these resistors
sets the divider string current. For lower divider string currents,
the small 10 nA (100 nA maximum) feedback bias current should
be taken into account when calculating the resistor values. The
feedback bias current can be ignored for a higher divider string
current; however, this degrades efficiency at very light loads.
To limit output voltage accuracy degradation due to feedback
bias current to less than 0.05% (0.5% maximum), ensure that
the divider string current is greater than 20 µA. To calculate the
desired resistor values, first determine the value of the bottom
divider string resistor, R1, using the following equation:
R1 = V
REF
/I
STRING
(2)
where:
V
REF
is the internal reference voltage, 0.6 V.
I
STRING
is the resistor divider string current.
When R1 is determined, calculate the value of the top resistor, R2,
using the following equation:






−
=
REF
REF
OUT
V
VV
R1R2
(3)
V
OUT1
/V
OUT2
L
R
V1SET
/
R
V2SET
V
IN
R
FREQ
VDD
FREQ
GND
V1SET/
V2SET
VINx
SWx
FB1/FB2
PGNDx
COMP1/
COMP2
ADP2116
08436-062
Figure 62. Configuration for Fixed Outputs
V
OUT1
/V
OUT2
L
R2
R1
R
V1SET
/
R
V2SET
V
IN
R
FREQ
VDD
FREQ
GND
V1SET/
V2SET
VINx
SWx
FB1/FB2
PGNDx
COMP1/
COMP2
ADP2116
08436-063
Figure 63. Configuration for Adjustable Outputs