Datasheet

JUMPER SHUNT POSITION DESCRIPTION
JU1
1-2 Connects FSYNC to V
BIAS
to enable continuous PWM mode.
2-3* Connects FSYNC to AGND to enable SKIP mode under light-load conditions.
Open
When FSYNC is unconnected or when a clock source is present, continuous PWM mode is
enabled. FSYNC can be used to synchronize with other supplies when a clock source is
present.
JU2
Closed Connects EN to AGND (shutdown).
Open* Connects EN to V
SUP
through a pullup resistor (normal operation).
MAX16952 Evaluation Kit
Evaluates: MAX16952
3Maxim Integrated
For external synchronization, apply a digital signal at the
FSYNC and SGND test points with a frequency between
1MHz and 2.42MHz. For proper frequency synchroniza-
tion, FSYNC’s input frequency must be at least 110% of
the EV kit’s programmed internal oscillator frequency.
When FSYNC is driven with an external digital clock, the
device synchronizes to the rising edge of the external
clock. The digital square-wave clock source at FSYNC
must provide the following signal qualities:
• 0 to 0.4V logic-low
• 1.4V to 5.5V logic-high
• 1MHz to 2.42MHz input frequency
• 100ns minimum pulse width
Enable Control (JU2)
The EV kit output is enabled through pullup resistor R11
when the power source applied between the SUP and
PGND test points is greater than 1.8V. To enable the EV
kit output, remove the shunt on jumper JU2. To disable
the EV kit output, install a shunt on JU2. See Table 2 for
JU2 configuration. If the EN pin is toggled from low to
high, the switching regulator shuts down and remains
off until the output voltage decays to 1.25V. At that point,
the EV kit output turns on using the soft-start sequence.
Switching Frequency
The controller’s approximate switching frequency is
set to 2.2MHz by resistor R8. Replace R8 with a new
resistor value to set the switching frequency between
1MHz and 2.2MHz. Refer to the Setting the Switching
Frequency section in the MAX16952 IC data sheet for
selecting R8 when reconfiguring the EV kit switching
frequency. When reconfiguring the EV kit switching
frequency, it is necessary to replace the compensation
network components C9, C10, R9, and power com-
ponents. Refer to the Design Procedure section in the
MAX16952 IC data sheet for computing new compensa-
tion and power component values.
Configuring the Output Voltage (OUT)
The EV kit step-down controller’s output voltage (OUT) is
configured to 5V. OUT can be reconfigured between 1V
and 10V by removing resistor R7 and inserting feedback
resistors at the R5 and R6 (0603) PCB pads. To configure
the EV kit’s output voltage, refer to the Setting the Output
Voltage section in the MAX16952 IC data sheet for
instructions on selecting resistor values. Also refer to the
Effective Input-Voltage Range and Output Capacitor sec-
tions in the MAX16952 IC data sheet. Refer to the Design
Procedure section in the MAX16952 IC data sheet and
modify the compensation network accordingly.
Power-Good Indicator (D2)
The EV kit provides a red LED power-good indicator (D2)
to monitor undervoltage and overvoltage conditions at
OUT. D2 illuminates when OUT falls below 90% (typ) or
rises above 111% (typ) of its nominal regulated voltage.
Peak Inductor Current Limit
The device’s current-limit circuit uses differential current-
sense inputs (CS and OUT) to limit the peak inductor
current. The EV kit peak inductor current is set to 5.3A
using resistor R4. Use the following equation to calculate
the resistance needed to reconfigure the inductor peak
current limit:
ILIM
80mV
R4
I
=
where R4 is in milliohms and I
ILIM
is the peak inductor
current in amps.
*Default position.
Table 1. Jumper Descriptions (JU1, JU2)