MAX15048 Datasheet, PDF (4/7 Pages) Maxim Integrated Products – Evaluation Kit

MAX15049 Evaluation Kit
Triple Outputs
The MAX15049 EV kit’s three outputs are configured to
different voltages. The bottom side of the PCB contains
the IC and the feedback and compensation compo-
nents. The top side of the PCB contains the input/output
capacitors, inductors, and FETs. OUT1 is configured to
3.3V with resistors R3 and R6 and can supply up to 3A.
OUT2 is configured to 1.8V with resistors R9 and R12
and can supply up to 3A. OUT3 is configured to 1.2V
with resistors R16 and R18 and can supply up to 6A.
The output voltage for each output can be reconfigured
between 0.6V and 3.3V by replacing the respective feed-
back resistors. Refer to the Type III: Compensation When
ƒCO < ƒZERO, ESR section in the MAX15048/MAX15049
IC data sheet for instructions on selecting new resis-
tor values for the respective outputs. Also, refer to the
Inductor Selection and Input-Capacitor Selection sec-
tions in the IC data sheet to verify other component
replacements for proper operation when changing the
output voltage.
Current Limit
The MAX15049 EV kit uses the low-side MOSFET DC
on resistance (RDSON) for valley current sensing. The
current-limit threshold is 69mV internally set inside
the MAX15049. The MAX15049 compares the voltage
across the low-side MOSFET (RDSON) with the internal
threshold to incorporate the current limit. OUT1 and
OUT2 use the FDMC8200 FET with a low-side RDSON of
9.5mI (typ) and 13.5mI (max). The current-limit thresh-
old is 69mV (typ) and the output current limit calculated
is approximately 6A. The IRF7907 FET has similar char-
acteristics with a 9.1mI (typ) and 13.7mI (max) RDSON
and therefore, a similar current limit.
Switching Frequency
The MAX15049 PWM switching frequency is set to appro-
ximately 500kHz with resistor R21 (39.2kI). Replace
resistor R21 with a new resistor value to progam the
switching frequency between 200kHz and 1.2MHz. Use
the following equation to choose the appropriate resistor
value to reconfigure the switching frequency (fSW):
f_SW (kHz) = 12.8 × R21(kΩ)
Evaluating the MAX15048 (Tracking)
The MAX15049 EV kit comes configured for sequencing.
The EV kit can also evaluate the MAX15048 for tracking
applications. The MAX15049 IC must be replaced with
the MAX15048. It also requires modification at EN2
(pin 9) and EN3 (pin 24) for tracking operation with
the MAX15048. Refer to the MAX15048 Coincident/
Ratiometric Tracking (EN_) section in the MAX15048/
MAX15049 IC data sheet to calculate the proper values
for resistors R23–R26 and R29.
PGOOD Status Output
The MAX15049 EV kit provides a PGOOD logic output to
indicate the regulation state of OUT1, OUT2, and OUT3.
A logic-low at TP8 (PGOOD test point) indicates that one
of the output voltages has dropped below 92% of its
regulation voltage.
Individual EN_ Input
The MAX15049 EV kit provides an individual enable test
point for each output. The EV kit comes configured for
sequencing and connections so the enable test points
are not needed. To disable sequencing and externally
control each output, remove the sequencing compo-
nents (R23–R28) and apply a voltage on the EN_ test
point.
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