Features
1
Features
•
Works with low cost MSP430 based LaunchPad platform
•
Simple GUI to control EVM
•
EVM can be operated in three different modes
–
Auto run LED mode
–
Adjustable Voltage reference mode
–
Variable gain mode
•
Board is powered by USB
2
Introduction
The TPL0401 is an I2C bus controlled, single channel, linear-taper digital potentiometer with 128 wiper
positions. TPL0401A/B have an end-to-end resistance of 10k ohms and the low terminal internally
connected to ground. The position of the wiper can be adjusted using an I
2
C interface. The TPL0401 is
available in a 6-pin SC-70 package with a specified temperature range of
–
40
°
C to 125
°
C. The part has a
10k end-to-end resistance and can operate with a supply voltage range of 2.7V to 5.5V.
THE TPL0401EVM also consists of multiple other TI products (port expanders, LED drivers etc.).
However, the scope of this document is to illustrate the use of the EVM to evaluate the TPL0401. The
TPL0401EVM is designed to operate with the Texas Instruments LaunchPad (MSP-EXP430G2). The
TPL0401EVM comes with a preprogrammed MSP430G2553 microcontroller which is to be inserted in the
DIP socket on the LaunchPad. The LaunchPad can be separately purchased at www.ti.com/launchpad .
The TPL0401EVM has three different evaluation modes:
Mode 1
–
LED mode
–
This is the standard mode the TPL0401 comes up in when powered up. In this
mode the TPL0401 devices are used to control the color mixing on the RGB LEDs. The DPOTs are used
to set the current limit for the TLC59108 LED driver. This mode is and auto run mode that does not have
any GUI control. The flashing lights and color mixing is controlled by the keys on the board and other TI
products on the board.
Mode 2
–
Adjustable voltage reference mode
–
in this mode the TPL0401 is used in conjunction with an
LMV321 op amp as an adjustable voltage reference circuit.
Mode 3
–
Variable gain mode
–
in this mode the TPL0401 is configured as part of a variable gain
non-inverting amplifier. The gain of the amplifier can be controlled by a digital interface. This mode can be
used to evaluate the bandwidth of the TPL0501.
The EVM is operated by connecting the LaunchPad to a PC that has Windows
™
(with .NET) via the USB
Port. Other standard lab equipment such as Signal generator, multimeter, spectrum analyzer etc may be
required for detailed analysis of the TPL0501 performance using this EVM.
3
Mode Selection
To setup any of these two modes, begin by connecting the EVM to the LaunchPad. Note the location of
the VCC and GND pins on headers J1 and J2 on both the LaunchPad and the EVM to ensure correct
installation.
1. LED Mode
Connect Jumpers 1 and 2 of J6
C5V supply to J3
Connect LaunchPad to computer through USB cable
NOTE: It can be possible to power up the LEDs by connecting a wire from the VCC pin of J1 to the
positive pin of J3. A 5V supply might be required because the max voltage drop across the blue LED
plus the drop across the TLC59108 is larger than the supply voltage of the LaunchPad.
2. Voltage reference mode
Start up the board in LED mode as described earlier
Connect pins 1 and 2 of Jumper J7.
Connect pins 1 and 2 of Jumper J5.
Connect the LaunchPad and TPL0501EVM to a computer through the USB connector.
2
TPL0401EVM
SLIU008
–
September 2011
Copyright
©
2011, Texas Instruments Incorporated
