Datasheet

Evaluates: MAX15031
MAX15031 Evaluation Kit
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Output-Voltage Programmability
The MAX15031 EV kit features a jumper to set the
VOUT/APD voltage programmability. The output voltage
(VOUT/APD) is programmed by connecting an external
reference voltage source to the CNTRL and SGND PCB
pads. Remove the shunt at jumper JU1 to use the pro-
grammability feature and apply a reference voltage
< 1.25V to the CNTRL pad. When the voltage applied to
the CNTRL pad is > 1.5V, the MAX15031 internal refer-
ence is used. See Table 2 for jumper JU1 settings.
The output voltage at VOUT is set by resistors R1 and
R2 to 70V when jumper JU1 is installed. To reconfigure
the output for a different voltage (VIN + 1V to 76V),
select a new surface-mount 0603 resistor for R1. Refer
to the Setting the Output Voltage section in the
MAX15031 IC data sheet for selecting the R1 value.
Current-Monitor Output (MOUT)
and APD Load Simulator
The MOUT PCB pad provides a current-monitor output
that sources a current 1/10th the APD current. An RC
network comprised of resistor R3 and capacitor C7
provide a filter to the MOUT signal. Capacitor C7 is not
required in a typical design.
Additionally, resistors R8 and R9 set the APD load simu-
lator circuit’s current for current-monitor step-response
measurements. Apply a 0 to 11V square-wave signal to
the APD_DRV pad to simulate a 0 to 4mA load. Use test
points TP1 or TP2 to measure the APD load current and
TP3 as the SGND. Refer to the Monitor Current Limit
(RLIM)
section in the MAX15031 IC data sheet for addi-
tional information on the MOUT features.
Clamp Input (CLAMP)
The CLAMP input PCB pad is used for voltage clamp-
ing the MOUT pin. Capacitor C6 provides filtering to
the clamp voltage signal. The MAX15031 EV kit is
capable of clamping MOUT voltages between 0.6V to
76V (typ). To clamp MOUT in the range of 0.6V to 4.3V,
apply a voltage between 0 and 3.7V (typ) to the
CLAMP and SGND PCB pads. Refer to the Clamping
the Monitor Output Voltage (CLAMP) section in the
MAX15031 IC data sheet for additional information on
the CLAMP features.
Fast Current-Limit Threshold
and
ILIM Output
Resistor R5 sets the MAX15031 APD fast current-limit
threshold to 4.3mA. To reconfigure the circuit for anoth-
er current-limit threshold, replace resistor R5 and use
the following equation to calculate a new value for the
desired current:
where I
LIMIT
is the desired DC load current in mil-
liamps.
The ILIM open-drain signal is available at the ILIM PCB
pad. Resistor R6 pulls up the ILIM pin to VIN; when low,
the MAX15031 is in current limit. To interface with a
microcontroller, connect to the ILIM PCB and SGND
pads. Refer to the Monitor Current Limit (RLIM) section in
the MAX15031 IC data sheet for additional information
on the ILIM feature.
Rk
V
ImA
LIMIT
5
10 1 245
()
.
()
Ω=
×
Table 2. Output-Voltage Programming
(Jumper JU1)
SHUNT
POSITION
CNTRL
PIN
OUTPUT-VOLTAGE
PROGRAMMING
Installed
Connected
to VIN
Fixed output voltage: Internal
reference voltage used
Not
installed
Connected
to external
reference
P r og r am m ab l e outp ut vol tag e:
Ap p l y an exter nal r efer ence vol tag e
( < 1.25V ) at C N TRL P C B p ad
Not
installed
Connected
to external
reference
Fixed output voltage: Apply an
exter nal r efer ence vol tag e ( > 1.5V *)
at CNTRL PCB pad; internal
reference voltage used
*Apply a voltage exceeding 1.5V to use the MAX15031 internal
reference. The voltage should be in the range of 1.5V to VIN
voltage. Refer to the Adjusting the Boost Converter Output
Voltage (FB/CNTRL) section in the MAX15031 IC data sheet for
information.