Datasheet

ADP2114 Data Sheet
Rev. B | Page 24 of 40
CONVERTER CONFIGURATION
SELECTING THE OUTPUT VOLTAGE
To set the output voltage, V
OUT1
(V
OUT2
), select one of the six
fixed voltages, as shown in Table 4, by connecting the V1SET
(V2SET) pin to GND through an appropriate value resistor (see
Figure 70). V1SET and V2SET set the voltage output levels for
Channel 1 and Channel 2, respectively. The feedback pin FB1
(FB2) should be directly connected to V
OUT1
(V
OUT2
).
Table 4. Output Voltage Programming
R
V1SET
(Ω) ± 5% V
OUT1
(V) R
V2SET
(Ω) ± 5% V
OUT2
(V)
0 to GND 0.8 0 to GND 0.8
4.7 k to GND 1.2 4.7 k to GND 1.2
8.2 k to GND 1.5 8.2 k to GND 1.5
15 k to GND 1.8 15 k to GND 1.8
27 k to GND 2.5 27 k to GND 2.5
47 k to GND 3.3 47 k to GND 3.3
82 k to GND 0.6 to <1.6
(adjustable)
82 k to GND 0.6 to <1.6
(adjustable)
0 to VDD 1.6 to 3.3
(adjustable)
0 to VDD 1.6 to 3.3
(adjustable)
If the required output voltage V
OUT1
(V
OUT2
) is in the adjustable
range, from 0.6 V to less than 1.6 V, connect V1SET (V2SET)
through an 82 kΩ resistor to GND. For the adjustable output
voltage range of 1.6 V to 3.3 V, tie V1SET (V2SET) to VDD (see
Table 4). The adjustable output voltage of ADP2114 is externally
set by a resistive voltage divider from the output voltage to the
feedback pin (see Figure 71). The ratio of the resistive voltage
divider sets the output voltage, while the absolute value of those
resistors sets the divider string current. For lower divider string
currents, the small 10 nA (0.1 µA maximum) FB bias current
should be taken into account when calculating the resistor
values. The FB 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 FB 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, by
R1 = V
REF
/I
STRING
(2)
where:
V
REF
is 0.6 V, the internal reference.
I
STRING
is the resistor divider string current.
When R1 is determined, calculate the value of the top resistor,
R2, by






−
=
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
ADP2114
08143-070
Figure 70. 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
ADP2114
08143-071
Figure 71. Configuration for Adjustable Outputs