ADP2386-EVALZ Analog Devices, ADP2386-EVALZ Datasheet - Page 12

• 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

ADP2386
THEORY OF OPERATION
The
that uses a current-mode architecture with an integrated high-
side power switch and a low-side synchronous rectifier. The
regulator targets high performance applications that require
high efficiency and design flexibility.
The
4.5 V to 20 V and regulates the output voltage from 0.6 V to 90%
of the input voltage. Additional features that maximize design
flexibility include the following: programmable switching
frequency, programmable soft start, external compensation,
precision enable, and a power-good output.
CONTROL SCHEME
The
control architecture. At the start of each oscillator cycle, the high-
side N-MOSFET is turned on, putting a positive voltage across
the inductor. When the inductor current crosses the peak inductor
current threshold, the high-side N-MOSFET is turned off and
the low-side N-MOSFET is turned on. This puts a negative voltage
across the inductor, causing the inductor current to decrease.
The low-side N-MOSFET stays on for the rest of the cycle (see
Figure 17).
PRECISION ENABLE/SHUTDOWN
The EN input pin has a precision analog threshold of 1.17 V
(typical) with 100 mV of hysteresis. When the enable voltage
exceeds 1.17 V, the regulator turns on; when it falls to less than
1.07 V (typical), the regulator turns off. To force the regulator
to automatically start when input power is applied, connect EN
to PVIN.
The precision EN pin has an internal pull-down current source
(5 µA) that provides a default turn-off when the EN pin is open.
When the EN pin voltage exceeds 1.17 V (typical), the
is enabled and the internal pull-down current source at the EN
pin decreases to 1 µA, which allows users to program the PVIN
UVLO and hysteresis.
INTERNAL REGULATOR (VREG)
The on-board regulator provides a stable supply for the internal
circuits. It is recommended that a 1 µF ceramic capacitor be
placed between the VREG and GND pins. The internal regulator
includes a current-limit circuit to protect the output if the
maximum external load current is exceeded.
ADP2386
ADP2386
ADP2386
operates from an input voltage that ranges from
is a synchronous step-down, dc-to-dc regulator
uses a fixed frequency, peak current-mode PWM
ADP2386
Rev. A | Page 12 of 24
BOOTSTRAP CIRCUITRY
The
voltage for the high-side N-MOSFET. It uses differential sensing to
generate a 5 V bootstrap voltage between the BST and SW pins.
It is recommended that a 0.1 µF, X7R or X5R ceramic capacitor
be placed between the BST pin and the SW pin.
OSCILLATOR
The
A resistor from RT to GND can program the switching frequency
according to the following equation:
A 100 kΩ resistor sets the frequency to 600 kHz, and a 42.2 kΩ
resistor sets the frequency to 1.2 MHz. Figure 29 shows the
typical relationship between f
SYNCHRONIZATION
To synchronize the ADP2386, connect an external clock to the
SYNC pin. The external clock frequency can be in the range
of 200 kHz to 1.4 MHz. During synchronization, the regulator
operates in continuous conduction mode (CCM), and the rising
edge of the switching waveform runs 180° out of phase to the rising
edge of the external clock.
When the
must be connected from the RT pin to GND to program the
internal oscillator to run at 90% to 110% of the external
synchronization clock.
ADP2386
ADP2386
f
SW
1400
1200
1000
800
600
400
200
(kHz) =
0
20
ADP2386
includes a regulator to provide the gate drive
switching frequency is controlled by the RT pin.
60
Figure 29. Switching Frequency vs. R
R
T
(k
operates in synchronization mode, a resistor
69120
100
Ω
)
+
140
15
SW
R
T
and R
(kΩ)
180
T
.
220
Data Sheet
T
260
300