Datasheet

Data Sheet ADP2119/ADP2120
Rev. A | Page 19 of 24
Table 6. Recommended L and C
OUT
Values for the ADP2120
V
IN
(V)
V
OUT
(V)
L (µH)
C
OUT
(µF)
3.3 1.0 1.5 22 + 10
3.3 1.2 1.5 22 + 10
3.3 1.5 1.5 22 + 10
3.3 1.8 1.5 10 + 10
3.3 2.5 1.5 10 + 10
5 1.0 1.5 22 + 10
5 1.2 1.5 22 + 10
5 1.5 2.2 22 + 10
5 1.8 2.2 10 + 10
5
2.5
2.2
10 + 10
5 3.3 2.2 10 + 10
Higher or lower inductor and output capacitor values can be
used in the regulator, but the system stability and load transient
performance need to be checked. The minimum output capacitor
is 22 µF for the ADP2119 and 10 µF for the ADP2120, and the
inductor range is 1 µH to 3.3 µH.
Table 7. Recommended Inductors
Manufacturer Part Number
Sumida
CDRH5D18BHPNP, CDR6D23MNNP
TOKO DE4518C, D62LCB
Coilcraft LPS5030, LPS5015
Table 8. Recommended Capacitors
Manufacturer Part Number Description
Murata GRM31CR60J226KE19 22 µF, 6.3 V, X5R, 1206
Murata GRM319R60J106KE19 10 µF, 6.3 V, X5R, 1206
TDK C3216X5R0J226M 22 µF, 6.3 V, X5R, 1206
TDK C3216X5R0J106M 10 µF, 6.3 V, X5R, 1206
INPUT CAPACITOR SELECTION
The input capacitor reduces the input voltage ripple caused by the
switch current on PVIN. Place the input capacitor as close as
possible to the PVIN pin. A 10 µF or 22 µF ceramic capacitor is
recommended. The rms current rating of the input capacitor
should be larger than calculated by the following equation:
)1( DDII
ORMS
−××=
VOLTAGE TRACKING
The ADP2119/ADP2120 include a tracking feature that allows
the output (slave voltage) to be configured to track an external
voltage (master voltage), as shown in Figure 51.
ADP2119/
ADP2120
TRK
FB
V
MASTER
R
TRKB
R
TRKT
R
BOT
R
TOP
V
SLAVE
08716-051
Figure 51. Voltage Tracking
A common application is coincident tracking (see Figure 52).
Coincident tracking limits the slave output voltage to be the
same as the master voltage until it reaches regulation. Connect
the TRK pin to a resistor divider from the master voltage. For
coincident tracking, set R
TRKT
= R
TOP
and R
TRKB
= R
BOT
.
VOLTAGE
TIME
V
MASTER
V
SLAVE
08716-052
Figure 52. Coincident Tracking
Ratiometric tracking is shown in Figure 53. The slave output is
limited to a fraction of the master voltage. In this application,
the slave and master voltages reach the final value at the same
time. The ratio of the slave output voltage to the master voltage
is a function of the two dividers (see the following equation).
TRKB
TRKT
BOT
TOP
MASTER
SLAVE
R
R
R
R
V
V
+
+
=
1
1
VOLTAGE
TIME
V
MASTER
V
SLAVE
08716-053
Figure 53. Ratiometric Tracking