ADP1871ACPZ-1.0-R7 Analog Devices Inc, ADP1871ACPZ-1.0-R7 Datasheet - Page 24

• Manufacturer Part Number: ADP1871ACPZ-1.0-R7
• Description: 1.0MHz, Light Load Eff Enabled
• Manufacturer: Analog Devices Inc

Specifications of ADP1871ACPZ-1.0-R7

• Frequency - Max: 1MHz
• Pwm Type: Current Mode
• Number Of Outputs: 1
• Duty Cycle: 45%
• Voltage - Supply: 2.95 V ~ 20 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 10-WFDFN, CSP Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADP1871ACPZ-1.0-R7; ADP1871ACPZ-1.0-R7TR

ADP1870/ADP1871
APPLICATIONS INFORMATION
FEEDBACK RESISTOR DIVIDER
The required resistor divider network can be determined for a
given V
is fixed at 0.6 V. Selecting values for R
minimum output load current of the converter. Therefore, for a
given value of R
following expression:
INDUCTOR SELECTION
The inductor value is inversely proportional to the inductor
ripple current. The peak-to-peak ripple current is given by
where K
The equation for the inductor value is given by
where:
V
V
f
1.0 MHz).
When selecting the inductor, choose an inductor saturation
rating that is above the peak current level, and then calculate
the inductor current ripple (see the Valley Current-Limit
Setting section and Figure 79).
SW
Figure 79. Peak Inductor Current vs. Valley Current Limit for 33%, 40%, and
IN
OUT
is the controller switching frequency (300 kHz, 600 kHz, and
is the high voltage input.
is the desired output voltage.
R
Δ
L
T
I
52
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
=
OUT
8
L
I
=
6
is typically 0.33.
(
=
V
R
Δ
value because the internal band gap reference (V
K
IN
B
I
8
L
I
×
−
×
×
(
B
V
V
10
, the R
I
f
LOAD
OUT
OUT
SW
50% of Inductor Ripple Current
0
12
6 .
)
−
VALLEY CURRENT LIMIT (A)
×
≈
T
V
0
14
value can be determined through the
V
6 .
I
V
LOAD
OUT
IN
V)
3
16
18
20
T
and R
ΔI = 40%
22
ΔI = 50%
24
B
determines the
ΔI = 33%
26
28
30
REF
Rev. A | Page 24 of 44
)
Table 8. Recommended Inductors
L
(μH)
0.12
0.22
0.47
0.72
0.9
1.2
1.0
1.4
2.0
0.8
OUTPUT RIPPLE VOLTAGE (ΔV
The output ripple voltage is the ac component of the dc output
voltage during steady state. For a ripple error of 1.0%, the
output capacitor value needed to achieve this tolerance can be
determined using the following equation. (Note that an
accuracy of 1.0% is possible only during steady state conditions,
not during load transients.)
OUTPUT CAPACITOR SELECTION
The primary objective of the output capacitor is to facilitate the
reduction of the output voltage ripple; however, the output
capacitor also assists in the output voltage recovery during load
transient events. For a given load current step, the output
voltage ripple generated during this step event is inversely
proportional to the value chosen for the output capacitor. The
speed at which the output voltage settles during this recovery
period depends on where the crossover frequency (loop
bandwidth) is set. This crossover frequency is determined by
the output capacitor, the equivalent series resistance (ESR) of
the capacitor, and the compensation network.
To calculate the small-signal voltage ripple (output ripple
voltage) at the steady state operating point, use the following
equation:
where ESR is the equivalent series resistance of the output
capacitors.
To calculate the output load step, use the following equation:
where ΔV
a given positive load current step (ΔI
Δ
C
C
V
OUT
OUT
DCR
(mΩ)
0.33
0.33
0.67
1.3
1.6
1.8
3.3
3.2
2.6
2.5
RR
DROOP
=
=
=
2
Δ
. 0 (
×
I
I
(A)
55
30
50
35
28
25
20
24
22
16.5
SAT
is the amount that V
L
01
f
×
SW
)
⎛
⎜
⎜
⎝
×
8
×
V
Dimensions
(mm)
10.2 × 7
10.2 × 7
13.2 × 12.8
10.5 × 10.2
13 × 12.8
10.5 × 10.2
10.5 × 10.2
14 × 12.8
13.2 × 12.8
12.5 × 12.5
×
OUT
(
Δ
f
SW
V
DROOP
×
[
Δ
Δ
I
V
LOAD
−
RIPPLE
(
Δ
Manufacturer
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
AIC Technology
OUT
1
I
LOAD
LOAD
RR
−
is allowed to deviate for
)
(
).
Δ
×
I
L
ESR
×
ESR
))
)
]
Model
Number
744303012
744303022
744355147
744325072
744355090
744325120
7443552100
744318180
7443551200
CEP125U-R80
⎞
⎟
⎟
⎠