Datasheet

SHUNT
POSITION
CLK PIN
OSCILLATOR/CLOCK
OPERATION
Installed*
Connected
to GND
Internal oscillator
Not installed
Not con-
nected
External clock; apply a clock
signal to the CLK PCB pad
on the EV kit
CONFIGURATION C7 C8 D1 D2 D3 D4 R7 R8 R9 R10
Full-wave
rectifier*
Not
installed
Not
installed
Installed Installed Installed Installed
Not
installed
Not
installed
0I 0I
Half-wave
rectifier
Not
installed
Not
installed
Not
installed
Installed
Not
installed
Not
installed
0I
Not
installed
0I 0I
Voltage doubler
Not
installed
Installed Installed Installed
Not
installed
Not
installed
0I
Not
installed
0I
Not
installed
Bipolar outputs
1FF
Not
installed
Installed Installed Installed Installed
Not
installed
Installed
10kI 0I
Push-pull rectifier
Not
installed
Not
installed
Not
installed
Installed
Not
installed
Installed
Not
installed
0I 0I 0I
SHUNT POSITION
EN PIN
DEVICE OPERATION
1-2 Connects to 5V Disables the device
2-3* Connects to GND Enables the device
SHUNT
POSITION
LDO’S EN PIN
LDO
OPERATION
Installed Connects to GND Disables the LDO
Not installed* Not connected Enables the LDO
_________________________________________________________________ Maxim Integrated Products 3
MAX13256 Evaluation Kit
Evaluates: MAX13256
On-Board LDO for
Disabling the MAX13256
The EV kit features an on-board 5V LDO (U2) for
disabling the MAX13256 and powering the LED con-
nected to FAULT. Install a shunt in the 1-2 position on
jumper JU1 to connect the EN pin of the device to the 5V
from the LDO output and disable the device. Ensure that
the voltage on EN never exceeds 6V.
Jumper JU4 is used to disable and enable the LDO, as
shown in Table 3.
Overcurrent Limiting
Resistor R1 sets the current-limit threshold to 650mA. To
change the current-limit threshold, replace resistor R1
with a 0603 surface-mount resistor using the following
equation:
( )
LIM
R1 k = 650/I (mA)Ω
where I
LIM
is the desired current threshold in the range
of 215mA < I
LIM
< 650mA.
An overcurrent or overtemperature condition triggers a
fault on the device and the red LED (D5) turns on.
Evaluating Other
Transformer Configurations
The EV kit PCB layout provides an easy method to
reconfigure transformer T1 secondary windings for other
configurations, including a half-wave rectifier, voltage
doubler, bipolar outputs, and other full-wave-rectifier
configurations. Use Table 4 to reconfigure the device for
the appropriate output configuration.
Output Snubbers
For VDD greater than 27V, use a simple RC snubber
circuit on ST1 and ST2 to ensure that the peak voltage
is less than 40V during switching. Maxim recommends
installing 91I 0603 surface-mount resistors at R5 and
R6, and 330pF 0603 surface-mount capacitors at C2 and
C3 when operating under these conditions.
Table 2. Clock Mode (JU2)
Table 4. Output Configurations
Table 1. EN (JU1)
Table 3. LDO Enable (JU4)
*Default position.
*Default position.
*Default position.
*Default position.