Datasheet
ADP2114 Data Sheet
Rev. B | Page 32 of 40
5. Calculate the feedback loop, compensation component
values by using Equation 15.
H(s) = g
m
× G
CS
×
OUT
REF
V
V
× Z
COMP
(s) × Z
FILT
(s)
In this case, the following values are substituted for the
variables in Equation 18:
g
m
= 550 µs
G
CS
= 4
V
REF
= 0.6 V
V
OUT
= 1.8 V
C
OUT
= 0.8 × (47+22) µF (capacitance derated by 20% to
account for dc bias).
From Equation 18,
R
COMP
= 22 kΩ.
Substituting R
COMP
in Equation 19 yields C
COMP
= 1100 pF.
Table 11. Channel 2 Circuit Settings
Circuit Parameter Setting Value
Output Voltage, V
OUT
Nominal 1.8 V
Reference Voltage, V
REF
Typical 0.6 V
Error Amp Transconductance, g
m
Typical 550 µs
Current Sense Gain, C
CS
Typical 4 A/V
Switching Frequency, f
SW
Step 2 600 kHz
Crossover Frequency, f
CROSS
1/12 f
SW
50 kHz
Zero Frequency, f
ZERO
1/8 f
CROSS
6.25 kHz
Output Inductor, L
OUT
Step 3 3.3 µF
Output Capacitors, C
OUT
Step 4 47 µF + 22 µF
Compensation Resistor, R
COMP
Equation 18 22 kΩ
Compensation Capacitor, C
COMP
Equation 19 1100 pF
SYSTEM CONFIGURATION
Complete the following steps to further configure the ADP2114
for this design example:
1. Set the switching frequency (f
SW
) = 600 kHz (see Table 5)
by connecting the FREQ pin through an 8.2 kΩ resistor
to GND.
2. Tie SCFG to VDD and use the CLKOUT signal to
synchronize other converters on the same board with the
ADP2114.
3. Tie OPCFG to GND for 2 A/2 A maximum output current
operation and to enable pulse skip mode at light load
conditions (see Table 7).
A schematic of the ADP2114 as configured in the design example
described in this section is shown in Figure 79.
Table 12 provides the recommended inductor, output capacitor,
and compensation component values for a set of popular input
and output voltage combinations.
Table 12. Selection Table of L, C
OUT
, and Compensation Values
f
SW
(kHz) V
IN
(V) V
OUT
(V) Maximum Load (A) L (µH) C
OUT
(µF) R
COMP
(kΩ) C
COMP
(pF)
300
5 3.3 2.0 6.8 69 (47 + 22) 20 2400
300
5 2.5 2.0 6.8 100 22 2400
300
5 1.8 2.0 6.8 147 (100 + 47) 22 2400
300
5 1.2 2.0 4.7 200 (2 × 100 ) 20 2400
600
5 3.3 2.0 3.3 47 27 1000
600
5 2.5 2.0 3.3 57 (47 + 10) 24 1100
600
5 1.8 2.0 3.3 69 (47 + 22) 22 1100
600
5 1.2 2.0 2.2 100 20 1200
1200
5 2.5 2.0 1.8 32 (22 + 10) 27 470
1200
5 1.8 2.0 1.8 44 (2 × 22) 27 470
1200
5 1.2 2.0 1.2 57 (47 + 10) 24 510
1200
5 0.8 2.0 1.0 100 27 470