ADP2386-EVALZ Analog Devices, ADP2386-EVALZ Datasheet - Page 15

• Manufacturer Part Number: ADP2386-EVALZ
• Description: Power Management IC Development Tools 20V 6A Evaluation Board
• Manufacturer: Analog Devices
• Type: DC/DC Converters, Regulators & Controllersr
• Series: ADP2386r

Specifications of ADP2386-EVALZ

• Rohs: yes
• Tool Is For Evaluation Of: ADP2386
• Input Voltage: 4.5 V to 20 V
• Factory Pack Quantity: 1

Data Sheet
APPLICATIONS INFORMATION
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 ceramic capacitor in the 10 μF to
47 μF range is recommended. The loop that is composed of this
input capacitor, the high-side N-MOSFET, and the low-side N-
MOSFET must be kept as small as possible.
The voltage rating of the input capacitor must be greater than
the maximum input voltage. Ensure that the rms current rating
of the input capacitor is larger than the value calculated from
the following equation:
OUTPUT VOLTAGE SETTING
The output voltage of the
divider. The resistor values are calculated using
To limit the output voltage accuracy degradation due to the FB
bias current (0.1 µA maximum) to less than 0.5% (maximum),
ensure that R
Table 6 lists the recommended resistor divider values for the
various output voltages.
Table 6. Resistor Divider Values for Various Output Voltages
V
1.0
1.2
1.5
1.8
2.5
3.3
5.0
VOLTAGE CONVERSION LIMITATIONS
The minimum output voltage for a given input voltage and
switching frequency is constrained by the minimum on time.
The minimum on time of the
The minimum output voltage for a given input voltage and
switching frequency can be calculated using the following:
where:
V
V
t
f
R
R
I
R
MIN_ON
SW
OUT_MIN
OUT
DSON_HS
DSON_LS
L
OUT_MIN
IN
is the series resistance of the output inductor.
is the switching frequency.
is the input voltage.
I
V
(V)
V
I
C IN
OUT_MIN
OUT_MIN
OUT
is the minimum on time.
is the minimum output current.
_
is the low-side MOSFET on resistance.
is the high-side MOSFET on resistance.
is the minimum output voltage.
RMS
= 0.6 ×
× t
= I
= V
BOT
MIN_ON
OUT
IN
< 30 kΩ.

 

× t
1
×
+
MIN_ON
× f
R
10
10
15
20
47.5
10
22
R
R
D
SW
TOP
TOP
BOT
ADP2386
×
− (R
× f
± 1% (kΩ)
1 ( D

 

SW
ADP2386
−
DSON_LS
− (R
)
is set by an external resistive
DSON_HS
+ R
is typically 125 ns.
L
) × I
− R
R
15
10
10
10
15
2.21
3
OUT_MIN
BOT
DSON_LS
± 1% (kΩ)
) ×
Rev. A | Page 15 of 24
(1)
The maximum output voltage for a given input voltage and
switching frequency is constrained by the minimum off time
and the maximum duty cycle. The minimum off time is typically
200 ns, and the maximum duty cycle of the
typically 90%.
The maximum output voltage, limited by the minimum off time
at a given input voltage and switching frequency, can be calculated
using the following equation:
where:
V
V
t
f
R
R
I
R
The maximum output voltage, limited by the maximum duty
cycle at a given input voltage, can be calculated using the
following equation:
where D
As shown in Equation 1 to Equation 3, reducing the switching
frequency alleviates the minimum on time and minimum off
time limitation.
INDUCTOR SELECTION
The inductor value is determined by the operating frequency,
input voltage, output voltage, and inductor ripple current. Using
a small inductor value leads to a faster transient response; however,
it degrades efficiency, due to a larger inductor ripple current.
Using a large inductor value leads to smaller ripple current and
better efficiency, but it results in a slower transient response.
As a guideline, the inductor ripple current, ΔI
to one-third of the maximum load current. The inductor value
is calculated using the following equation:
where:
V
V
D is the duty cycle (D = V
ΔI
f
The
loop to prevent subharmonic oscillations when the duty cycle
is larger than 50%. The internal slope compensation limits the
minimum inductor value.
MIN_OFF
SW
SW
OUT_MAX
DSON_HS
DSON_LS
L
OUT_MAX
IN
IN
OUT
L
is the series resistance of the output inductor.
is the switching frequency.
is the switching frequency.
is the input voltage.
is the input voltage.
is the inductor current ripple.
ADP2386
V
I
V
L =
is the output voltage.
OUT_MAX
OUT_MAX
OUT_MAX
is the minimum off time.
is the low-side MOSFET on resistance.
is the maximum output current.
is the high-side MOSFET on resistance.
MAX
is the maximum output voltage.
(
V
IN
is the maximum duty cycle; V
∆
× (1 − t
= V
= D
−
I
L
uses adaptive slope compensation in the current
V
×
OUT
IN
MAX
f
SW
× (1 − t
)
MIN_OFF
×
× V
D
IN
OUT
MIN_OFF
× f
/V
SW
IN
) − (R
).
× f
SW
DSON_LS
) − (R
IN
ADP2386
+ R
is the input voltage.
DSON_HS
L
, is typically set
L
) × I
ADP2386
− R
OUT_MAX
is
DSON_LS
) ×
(2)
(3)