www.ti.com
PWM, Analog, and Single-Ended Inputs
17
SLOU403C – March 2015 – Revised June 2018
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
DRV2700EVM High Voltage Piezo Driver Evaluation Kit
Figure 10. Set Reference to External 2.5 V
See
Figure 13
for a diagram of the input configuration.
5.4.2
Floating Reference
If the application is to create a high voltage square wave where the output goes from ±V
BST
, this floating
reference configuration is beneficial. Unlike most amplifiers where both input terminals need to be biased
to control the output, the DRV2700 has an internal compensated common mode to try and keep the inputs
near V
DD
/ 2. This allows the application to eliminate the need of a reference voltage, by instead applying a
capacitor to ground on one of the input terminals. Because there is compensation between the two inputs,
the common mode will have some drift based on the other input signal. If the DRV2700 is going to be
operated in the linear region, the set reference configuration should be used.
Use the DC input with a floating reference to drive the DRV2700 with the following instructions:
1. Disconnect the MSP430 output pins from the DRV2700 input pins by removing jumpers JP6 and JP5
2. Connect DRV2700 control signals:
a. Use the onboard MSP430 and GUI to control the EN, GAIN0, and GAIN1 pins
b. Use an external controller or jumpers to control the EN, GAIN0, and GAIN1 pins
3. Amplifying signal:
a. For 0–10 V range, connect jumper JP_DC and apply 0–10 V on DC_IN
b. For 0–5 V range, disconnect jumper JP_DC and apply 0–5 V on TP7 (IN+)
4. Enable the power supply
Figure 11
and
Figure 12
show this mode at 3 Hz and 1 KHz. Notice that the floating reference (IN-) will
vary based on the IN+ signal. This drift can be minimized by increasing the frequency. This configuration
should only be used as long as the application can handle this drift. Each application should be properly
evaluated to verify if this configuration will be acceptable per its system requirements.
Figure 11
and
Figure 12
are with the EVM powered through USB (5 V).
See
Figure 13
for a diagram of the input configuration.
