Datasheet

MAX5392 Evaluation System
Evaluates: MAX5387/MAX5392
_______________________________________________________________________________________ 9
Problem: Software reports no devices found
• Are shunts installed at jumpers JU1, JU2, JU10, and
JU22 (power sources for MAX5392)?
• Are the SCL and SDA signals pulled up to VPOWER
(resistors R6, R7, R9, and R10 installed)?
• Are shunts installed at jumpers JU15, JU16, and
JU17 (set device address)?
• If using an external power supply, verify that power
is applied to the EV kit VDD and GND PCB pads.
• If using an off-board 2-wire interface, is the power
ground connected to the EV kit ground (GND) at
one of the header J1 pin connections (J1-2, J1-4,
or J1-6)?
Detailed Description of Hardware
The MAX5392 evaluation kit (EV kit) is an assembled and
tested PCB that features two MAX5392M 50kI dual digi-
tal potentiometers. The potentiometers have end-to-end
resistance of 50kI and each wiper can be programmed
independently among 256 tap positions. The EV kit uses
two MAX5392M ICs (U3, U4) in 16-pin TSSOP packages
on a proven two-layer PCB design.
The MAX5392 ICs can be powered from a 2.6V, 3.3V,
or 5V source generated from the MINIQUSB+ interface
board and EV kit circuitry (applied at the EV kit VPOWER
rail), or from a user-supplied external 1.7V to 5.25V DC
power supply applied at the VDD and GND PCB pads.
U3 can be powered from the VPOWER rail or from a
1.7V source (U5) using jumpers JU2 and JU10. U4 can
be powered from U3 VDD input or from the VPOWER rail
using jumper JU22.
The EV kit provides connector J1 to interface the
MAX5392 SDA and SCL signals directly to a user-
supplied 2-wire system. Connector J1 also provides
a connection for the MAX5392 EV kit’s 1.7V to 5.25V
VPOWER power-supply rail.
The EV kit is typically used with a MINIQUSB+ interface
board for communicating with a PC through the SMBus/
I
2
C serial interface. Logic-level translators U7 and U8
provide proper interface translation when using 1.7V to
5.25V to power the MAX5392 VDD inputs.
The EV kit can also be used to evaluate the MAX5392L
(10kI) and MAX5392N (100kI). The MAX5392 EV kit
contains PCB footprints for two MAX5387 ICs, which
allows the user to independently control up to eight
potentiometers. To evaluate the MAX5387, order sam-
ples and replace the parts in U1 and/or U2.
EV Kit VDD Input Sources
The VPOWER rail is typically supplied as 3.3V or 5V by
the MINIQUSB+ interface board circuitry and 2.6V using
LDO regulator U6. LDO regulator U5 output is set to 1.7V
and is powered from the VPOWER rail. The VPOWER rail
and U5 set the MAX5392 VDD inputs to 5V, 3.3V, 2.6V,
or 1.7V.
Regulator U5 has an adjustable output that can be con-
figured to a different voltage by replacing resistor R1.
Use the following equation to set U5 output voltage:
5
VOUT
R1 10 1
1.225
 
= × −
 
 
where R1 is in ohms and VOUT is the desired U5 output
voltage.
Jumper JU1 selects the source for the EV kit circuit
VPOWER rail. See Table 3 for proper JU1 configuration
for setting VPOWER rail.
Jumper JU2 enables/disables U5 output. Install a shunt
across JU2 to enable U5’s 1.7V output. Remove the
shunt at JU2 to disable U5 output. See Table 4 for proper
JU2 configuration.
Alternatively, the EV kit VDD and GND PCB pads can be
used to supply an external 1.7V to 5.25V to the EV kit’s
VPOWER rail by removing the shunt at jumper JU1.
Table 3. VPOWER Rail (JU1) Table 4. U5 LDO Function (JU2)
*Default position.
SHUNT
POSITION
VPOWER SOURCE
1-2 5V (MINIQUSB+ circuitry)
1-3 3.3V ( MINIQUSB+ circuitry)
1-4 2.6V (LDO U6)
Not installed
External source applied at the EV kit
VDD and GND PCB pads
SHUNT POSITION U5 1.7V OUTPUT
Installed* Enabled
Not installed Disabled