Datasheet

ADP1610
Rev. A | Page 11 of 20
Table 4. Recommended Capacitor and Inductor Manufacturers
Vendor Part L (μH) C (μF)/Rating (V)
Maximum
DC Current
Maximum
DCR (mΩ) Height (mm) Comments
Sumida CMD4D11-2R2MC 2.2 0.95 116 1.2
CMD4D11-4R7MC 4.7 0.75 216 1.2
CDRH4D28-100 10 1.00 128 3.0
CDRH5D18-220 22 0.80 290 2.0
CR43-4R7 4.7 1.15 109 3.5
CR43-100 10 1.04 182 3.5
Coilcraft DS1608-472 4.7 1.40 60 2.9
DS1608-103 10 1.00 75 2.9
Toko D52LC-4R7M 4.7 1.14 87 2.0
D52LC-100M 10 0.76 150 2.0
Murata GRM32ER61A226KE20L 22/10
Used only for 3.3 V
input and 5 V output
GRM31CR61E106KA12L 10/25
Used for 9 V, 10 V,
and 12 V outputs
GRM31CR61A106KA01L 10/10
Used for inputs and
outputs of 5 V
GRM31CR71E475KA88L 4.7/25
Using the duty cycle and switching frequency (F
SW
), the on-time
is calculated using the following equation:
t
ON
=
SW
f
D
(4)
The inductor ripple current (I
L
) in steady state is calculated
using the following equation:
I
L
=
L
t
V
ON
IN
×
(5)
The inductance value (L) is calculated using the following
equation:
L =
L
ON
IN
I
tV
Δ
×
(6)
The peak inductor current (the maximum input current plus
half the inductor ripple current) must be less than the rated
saturation current of the inductor. Likewise, the maximum
rated rms current of the inductor must be greater than the
maximum dc input current to the regulator.
For duty cycles greater than 50%, which occur with input
voltages greater than one-half the output voltage, slope compensa-
tion is required to maintain stability of the current-mode regulator.
For stable current-mode operation, ensure that the selected
inductance is equal to or greater than L
MIN
using the following
equation:
SW
IN
OUT
MIN
f
VV
LL
×
=>
A8.1
(7)
CHOOSING THE INPUT AND OUTPUT CAPACITORS
The ADP1610 requires input and output bypass capacitors to
supply transient currents while maintaining constant input and
output voltage. To prevent noise at the ADP1610 input, a low
ESR (equivalent series resistance), 10 µF or greater input capacitor
is to be used. Place the capacitor between IN and GND as close to
the ADP1610 as possible. Ceramic capacitors are preferred because
of their low ESR characteristics. Alternatively, use a high value,
medium ESR capacitor in parallel with a 0.1 µF low ESR capacitor
as close to the ADP1610 as possible.
The output capacitor maintains the output voltage and supplies
current to the load while the ADP1610 switch is on. The value
and characteristics of the output capacitor greatly affect the
output voltage ripple and stability of the regulator. Use a low
ESR output capacitor; ceramic dielectric capacitors are preferred.
The input bypass capacitor limits the high frequency impedance
of the input voltage source. The value of this capacitor may
need to be increased if the wire length from the input voltage
source to the applications board is longer than 18” to optimize
the transient performance.