MAX1945 Maxim Integrated Products, MAX1945 Datasheet - Page 3

• Manufacturer Part Number: MAX1945
• Description: Evaluation Kit
• Manufacturer: Maxim Integrated Products

Table 1. Jumpers JU1, JU2 Functions
Table 2. Jumper JU3 Functions
TTL/CMOS digital clock. JU3 selects the switching
frequency or synchronization source for the
MAX1945R. Table 2 lists the jumper options.
The MAX1945 EV kit’s circuit can be synchronized to an
external TTL/CMOS digital clock using the SYNC and
GND PC board pads. The external clock provides a
square wave with the following signal specifications:
• Output voltage:
• Output frequency: 400kHz to 1.2MHz
• Duty cycle: 10% to 90%
JU3 must be reconfigured for the external clock (see
Table 2).
None; external
clock source
Logic high = 1.6V (min) to 5V (max)
Logic low = 0V (min) to 0.4V (max)
LOCATION
Installed
SHUNT
None
Connected to GND
Connected to GND
Connected to V
Connected to V
JUMPER JU1
IC CTL1 PIN
(installed)
(installed)
(SHUNT)
(none)
(none)
Connected to SYNC
Connected to GND
Clock Selection (SYNC Input)
Connected to V
_______________________________________________________________________________________
PC board pad
CC
CC
SYNC PIN
CC
Connected to GND
Connected to GND
Connected to V
Connected to V
1MHz switching
frequency
500kHz switching
frequency
External TTL/CMOS
digital clock provides
synchronization
JUMPER JU2
IC CTL2 PIN
(installed)
(installed)
(SHUNT)
FREQUENCY
(none)
(none)
MAX1945
CC
CC
MAX1945 Evaluation Kit
The MAX1945 EV kit features a PC board pad for the
SYNCOUT signal connection to evaluate a dual
postregulated power-supply design. Utilizing the SYN-
COUT signal as a TTL/CMOS digital clock to drive a
second MAX1945 EV kit enables the second
MAX1945R to switch 180 degrees out-of-phase relative
to the first EV kit. The second MAX1945 EV kit’s SYNC
input is driven by the SYNCOUT of the first EV kit. JU3
must be properly configured on both EV kits. The first
MAX1945 EV kit should be configured for 500kHz
switching frequency. The second EV kit must be config-
ured for an external TTL/CMOS digital clock (see Table
2). Use the GND pad near the SYNC and SYNCOUT
pads on both EV kits for the clock GND.
The MAX1945 EV kit provides a jumper to select the
output voltage that the EV kit can provide. JU4 config-
ures the EV kit for outputs of 1.8V, 2.5V, or an output
voltage determined by the R1 and R2 resistor-divider.
Table 3 lists the jumper options.
The MAX1945 EV kit step-down switching regulator
output is set to 1.8V by an internal feedback resistor
pair, resistor R1, and JU4. To generate output voltages
other than 1.8V (0.8V to 0.85x VIN), select different
external voltage-divider resistors R1 and R2. JU4 must
also be reconfigured. See Table 3 for configuring the
EV kit for other output voltages. Refer to the Setting the
Output Voltages section in the MAX1945 data sheet for
instructions on selecting feedback resistors R1 and R2,
and compensation components R3 and C5.
(+4% voltage margining)
(-4% voltage margining)
OUTPUT VOLTAGE
MAX1945 EV KIT
(nominal output)
(output is OFF)
Dual Power-Supply Design (SYNCOUT)
1.87V
1.73V
1.8V
0V
Evaluating Other Output Voltages
Output Voltage Selection
MAX1945 is enabled
MAX1945 is enabled
MAX1945 is enabled
MAX1945 is in shutdown
mode
MAX1945 STATUS
3