DRV2605L Datasheet, PDF (9/69 Pages) Texas Instruments – DRV2605L 2 to 5.2 V Haptic Driver for LRA and ERM With Effect Library and Smart-Loop Architecture

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DRV2605L
SLOS854C – MAY 2014 – REVISED SEPTEMBER 2014
7 Parameter Measurement Information
7.1 Test Setup for Graphs
To capture the graphs displayed in the Typical Characteristics section, the following first-order RC-filter setup
was used with the exception of the waveform in Figure 9 which was captured without any output filter. This filter
is recommended when viewing output signals on an oscilloscope because output PWM modulation is present in
all modes. Ensure that effective impedance of the filter is not too low because the closed-loop and auto
resonance-tracking features may be affected. Therefore, TI recommends that this exact filter be used for output
measurement. Most oscilloscopes have an input impedance of 1 MΩ on each channel and therefore have an
approximately 1% loss in measured amplitude because of the voltage-divider effect with the filter.
OUT+
OUT±
LRA
M or
ERM
100 k
100 k
470 pF
Ch1
Ch1 ± Ch2
Ch2 (Differential)
470 pF
Oscilloscope
Figure 11. Test Setup
7.1.1 Default Test Conditions
• V_DD = 3.6 V, unless otherwise noted.
• Real actuators (as opposed to modeled actuators) were used as loads for both ERM and LRA modes with
exception of the Supply Voltage vs Supply Current (Full Vibration) waveform in Figure 10, which used passive
RL (resistance in series with an inductance) loads for test repeatability. Real actuators vary widely in supply
currents because of variation in back-EMF voltages. Because real actuators have back EMF, the real supply
current is generally less than what is shown in the waveform because of the reduction in the apparent load
impedance. Therefore, the curve shows the worst-case current.
• All ERM library waveforms were taken with Library A in open-loop mode
• All LRA library waveforms were taken with the LRA Library in closed-loop mode
• All traces are 2 V/div except for the accelerometer traces
• All accelerometer traces are 0.87 g/div except for the LRA Click with and without Braking (PWM) curve in
Figure 8, which is 1.74 g/div.
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