ADP1828LC-EVALZ Analog Devices Inc, ADP1828LC-EVALZ Datasheet - Page 18

• Manufacturer Part Number: ADP1828LC-EVALZ
• Description: BOARD EVALUATION ADP1828LC
• Manufacturer: Analog Devices Inc

Specifications of ADP1828LC-EVALZ

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.8V
• Current - Output: 5A
• Voltage - Input: 5.5 ~ 13.2V
• Regulator Topology: Buck
• Frequency - Switching: 600kHz
• Board Type: Fully Populated
• Utilized Ic / Part: ADP1828
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

ADP1828
COMPENSATION
The control loop is compensated by an external series RC
network from COMP to FB and sometimes requires a series
RC in parallel with the top voltage divider resistor. COMP is
the output of the internal error amplifier.
The internal error amplifier compares the voltage at FB to the
internal 0.6 V reference voltage. The difference between the FB
voltage and the 0.6 V reference voltage is amplified by the open-
loop voltage 1000 volt-to-volt gain of the error amplifier. To
optimize the ADP1828 for stability and transient response for
a given set of external components and input/output voltage
conditions, choose the compensation components carefully. For
more information on choosing the compensation components,
see the Compensating the Voltage Mode Buck Regulator
section.
POWER-GOOD INDICATOR
The ADP1828 features an open-drain power-good output
(PGOOD) that sinks current when the output voltage drops
8.3% below or rises 25% above the nominal regulation voltage.
Two comparators measure the voltage at FB to set these thresh-
olds. The PGOOD comparator directly monitors FB, and the
threshold is fixed at 0.55 V for undervoltage and 0.75 V for
overvoltage. The PGOOD output also sinks current if an
overtemperature or input undervoltage condition is detected
and is operational with power-input voltage as low as 1.0 V.
Use this output as a logical power-good signal by connecting a
pull-up resistor from PGOOD to an appropriate supply voltage.
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THERMAL SHUTDOWN
In most applications, the ADP1828 controller itself does not
generate a significant amount of heat under normal conditions,
even when driving relatively large MOSFETs. However, the
surrounding power components or other circuits on the same
PCB could heat up the PCB to an unsafe operating temperature.
A thermal shutdown protection circuit on the ADP1828 shuts
off the LDO and the controllers if the die temperature exceeds
approximately 145°C, but this is a gross fault protection only
and should not be depended on for system reliability.
SHUTDOWN CONTROL
The ADP1828 dc-to-dc converter features a low power shut-
down mode that reduces the quiescent supply current to 20 μA,
or 40 μA when IN is tied to VREG. To shut down the ADP1828,
drive EN low. To turn it on, drive EN high or tristate EN. For
automatic startup, connect EN to IN.
TRACKING
The ADP1828 features a tracking input, TRK that makes the
output voltage track another voltage, that is, the master voltage.
This feature is especially useful in core and I/O voltage sequencing
applications where the output of the ADP1828 can be set to
track and not exceed another voltage.
The internal error amplifier includes three positive inputs—the
internal 0.6 V reference voltage, and the SS and TRK pins. The
error amplifier regulates the FB pin to the lowest of the three
inputs. To track a supply voltage, tie the TRK pin to a resistor
divider from the voltage to be tracked. If the TRK function is
not used, tie the TRK pin to VREG.