MAX5003EVKIT Maxim Integrated Products, MAX5003EVKIT Datasheet - Page 3

• Manufacturer Part Number: MAX5003EVKIT
• Description: EVAL KIT FOR MAX5003
• Manufacturer: Maxim Integrated Products

Specifications of MAX5003EVKIT

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 5V
• Current - Output: 1A
• Voltage - Input: 36 ~ 72V
• Regulator Topology: Buck
• Frequency - Switching: 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: MAX5003
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

LVL position disconnects the R1-R2 resistor-divider
from the MAX5003’s FB pin, as required for isolated
operation). Turn the power supply back on and verify
that the output voltage is still +5V. Note that for the iso-
lated configuration, the output ground and the input
ground may differ by as much as 500V. Do not oper-
ate switches SW1 and SW2 when power is applied
to the EV kit because the controller can be dam-
aged.
To configure the MAX5003 EV kit for operation in a sys-
tem in which the negative terminal of the input power
supply is at a more negative potential than the negative
terminal of the output power supply (for example, in a
-48V input to +5V output application), first turn off the
power supply and cut the JU1 PC board trace. Set the
SW1 switch to the NON position, and set the SW2
switch to the LVL position. Locate parts R18, R19, and
Q1 (directly above jumper JU1 on the PC board).
Solder the following parts into the R18, R19, and Q1
locations: R18 = 36.5kΩ ±1% resistor (1206), R19 =
12.4kΩ ±1% resistor (1206), and Q1 = 60V 2N2907-
type PNP transistor (SOT23). Note that the initial DC
output voltage accuracy and the temperature variation
will be degraded in this configuration. Do not operate
switches SW1 and SW2 when power is applied to
the EV kit because the controller can be damaged.
The MAX5003 EV kit is configured to go into undervolt-
age lockout when VIN drops below 32V. The MAX5003
does not have a shutdown pin, but the undervoltage
lockout state is equivalent to a shutdown state. The
MAX5003 EV kit contains a shutdown function consist-
ing of an NPN switching transistor (Q2) that can pull the
VINDIV pin to ground. To place the MAX5003 in under-
voltage lockout, drive the SHDN pad with a +5V logic-
Nonisolated Level-Shifted Feedback
_______________________________________________________________________________________
Undervoltage Lockout
and Shutdown
MAX5003 Evaluation Kit
high signal to turn on transistor Q2. For normal opera-
tion, the SHDN pad can be connected to ground or left
unconnected. Note that the logic-high signal used to
drive the SHDN pad is referenced to the negative side
of the input supply. For more details regarding under-
voltage lockout, refer to the MAX5003 data sheet.
The MAX5003 EV kit has a current-limiting feature
implemented by current-sense resistor R9. The
MAX5003 turns off switching FET N1 when the voltage
at the CS pin reaches 100mV. Since R9 is a 0.11Ω
resistor, this limits the current in the transformer primary
to 0.91A peak, which corresponds to a typical output
short-circuit current of 4.5A. R10, a 100Ω resistor, is
connected between the current-sense resistor and the
CS pin to enable current-sense blanking after N1 is
turned on, as described in the MAX5003 data sheet.
The MAX5003 EV kit layout is optimized for fast switch-
ing and high currents. The input and output power and
ground traces must both be as short and wide as pos-
sible to minimize unwanted parasitic inductance. This
board was not designed per UL spacing specifications.
Layout Considerations
Current Limiting
3