ADP2442-EVALZ Analog Devices, ADP2442-EVALZ Datasheet - Page 21

• Manufacturer Part Number: ADP2442-EVALZ
• Description: Power Management IC Development Tools Eval board
• Manufacturer: Analog Devices
• Type: DC/DC Converters, Regulators & Controllersr
• Series: ADP2442r

Specifications of ADP2442-EVALZ

• Rohs: yes
• Tool Is For Evaluation Of: ADP2442
• Factory Pack Quantity: 1

Data Sheet
Table 8. Inductor Values for Various V
Combinations
f
300
300
300
300
300
300
300
300
600
600
600
600
600
600
600
1000
1000
1000
1000
To avoid inductor saturation and ensure proper operation, choose
the inductor value so that neither the saturation current nor
the maximum temperature rated current ratings are exceeded.
Inductor manufacturers specify both of these ratings in data
sheets, or the rating can be calculated as follows:
where:
I
ΔI
I
Table 9. Recommended Inductors
Value (µH)
10
18
33
15
Output Capacitor Selection
The output capacitor selection affects both the output voltage
ripple and the loop dynamics of the regulator. The
designed to operate with small ceramic output capacitors that
have low ESR and ESL; therefore, the device easily meets tight
output voltage ripple specifications. For best performance, use
X5R or X7R dielectric capacitors with a voltage rating that is
1.5 times the output voltage and avoid using Y5V and Z5U die-
lectric capacitors, which have poor temperature and dc bias
characteristics. Table 10 lists recommended capacitors from
Murata and Taiyo Yuden.
SW
LOAD (MAX)
L_PEAK
L
(kHz)
is the peak-to-peak inductor ripple current.
I
L
is the peak inductor current.
_
PEAK
is the maximum dc load current.
=
V
12
12
24
24
24
36
36
36
12
12
24
24
24
36
36
12
24
24
36
Small Inductors
(<10 mm × 10 mm)
XAL4040-103ME
LPS6235-183ML
LPS6235-33ML
XAL4040-153ME
IN
I
LOAD
(V)
(
MAX
)
+
V
3.3
5
3.3
5
12
3.3
5
12
3.3
5
3.3
5
12
3.3
5
5
5
12
5
∆
OUT
2
I
L
(V)
Min (µH)
22
27
27
39
56
27
39
68
12
15
15
18
27
15
22
6.8
10
18
12
Large Inductors
(>10 mm × 10 mm)
MSS1260
MSS1260
MSS1260
MSS1260
IN
, V
Inductor Values
OUT
, and f
ADP2442
Max (µH)
27
33
33
47
68
33
47
82
15
18
18
22
33
18
27
10
12
22
15
SW
(10)
Rev. 0 | Page 21 of 36
is
Table 10. Recommended Output Capacitors
Capacitor
10 µF/25 V
22 µF/25 V
47 µF/6.3 V
4.7 µF/50 V
For acceptable maximum output voltage ripple, determine the
minimum output capacitance, C
Therefore,
where:
ΔV
ΔI
ESR is the equivalent series resistance of the capacitor.
f
When there is a step load requirement, choose the output
capacitor value based on the value of the step load. Use the
following equation to determine the maximum acceptable
output voltage droop/overshoot caused by the step load:
where:
ΔI
f
ΔV
Select the larger of the output capacitances derived from
Equation 12 and Equation 13. When choosing the type of
ceramic capacitor for the output filter of the regulator, select a
capacitor with a nominal capacitance that is 20% to 30% larger
than the calculated value because the effective capacitance
degrades with dc voltage and temperature. Figure 60 shows the
capacitance loss resulting from the dc bias voltage for two
capacitors (X7R MLCC capacitors from Murata are shown in
Figure 60).
SW
SW
L
OUT (STEP)
RIPPLE
DROOP
is the switching frequency of the regulator.
is the switching frequency of the regulator.
is the inductor ripple current.
C
C
∆
V
OUT
OUT
is the allowable peak-to-peak output voltage ripple.
is the maximum allowable output voltage droop/overshoot.
RIPPLE
(
(
is the load step.
MIN
MIN
)
)
Murata
GRM32DR71E106KA12L
GRM32ER71E226KE15L
GCM32ER70J476KE19L
GRM31CR71H475KA12L
≅
≅
≅
∆
∆
8
I
L
I
×
OUT
×
f




SW
ESR
(
STEP
×
(
∆
+
)
×
V
8




RIPPLE
×
∆
f
OUT (MIN)
I
SW
f
L
SW
Vendor
×
−
×
∆
∆
1
3
C
V
, as follows:
I
OUT
L
DROOP
×
Taiyo Yuden
TMK325B7106KN-TR
TMK325B7226MM-TR
JMK325B7476MM-TR
UMK325B7475MMT
(
ESR
MIN




)
)




ADP2442
(11)
(12)
(13)