Texas Instruments EVM for Piezo Haptic Driver with Boost, Digital Front End, and Internal Waveform Memory DRV2667EVM-CT DRV2667EVM-CT 데이터 시트
제품 코드
DRV2667EVM-CT
1
B OOST
FB
2
R
V
= V
1+
R
æ
ö
ç
÷
è
ø
FB
DRV2667
VBST
R1
R2
SLOS751A – MARCH 2013 – REVISED JANUARY 2014
APPLICATION INFORMATION
DEVICE STARTUP AND SHUTDOWN
The DRV2667 features a fast startup time, which is essential for achieving low latency in haptic applications.
When the STANDBY bit is transitioned from low to high, the device enters a low-power standby mode. When the
STANDBY bit is transitioned from high to low, the device is ready for operation. The device logic will
automatically control the internal boost converter and amplifier enable signals. The boost converter and amplifier
will be enabled only when needed and will otherwise remain in a lower power idle state. When the device
receives a data byte via the FIFO interface (Mode 1), or the GO bit is asserted (Mode 2 and Mode 3), the boost
converter and amplifier will wake up and the internal logic will send the first sample through the internal DAC
after the wake-up is completed. In the system application, the entire system latency should be kept to less than
30 ms total to be imperceptible to the end user. At a 2 ms wake-up time, the device will be a small percentage of
the total system latency.
When the STANDBY bit is transitioned from low to high, the device enters a low-power standby mode. When the
STANDBY bit is transitioned from high to low, the device is ready for operation. The device logic will
automatically control the internal boost converter and amplifier enable signals. The boost converter and amplifier
will be enabled only when needed and will otherwise remain in a lower power idle state. When the device
receives a data byte via the FIFO interface (Mode 1), or the GO bit is asserted (Mode 2 and Mode 3), the boost
converter and amplifier will wake up and the internal logic will send the first sample through the internal DAC
after the wake-up is completed. In the system application, the entire system latency should be kept to less than
30 ms total to be imperceptible to the end user. At a 2 ms wake-up time, the device will be a small percentage of
the total system latency.
If the EN_Override bit is set, the device will immediately enter the startup procedure and the boost converter
amplifier will remain enabled, bypassing the internal controls. Subsequent transactions will occur immediately
with no wake-up overhead, but the boost converter and amplifier will draw quiescent current until the
EN_Override bit is cleared by the user.
amplifier will remain enabled, bypassing the internal controls. Subsequent transactions will occur immediately
with no wake-up overhead, but the boost converter and amplifier will draw quiescent current until the
EN_Override bit is cleared by the user.
PROGRAMMING THE BOOST VOLTAGE
The boost output voltage is programmed via two external resistors as shown in the diagram below.
The boost output voltage is given by
(1)
where V
FB
= 1.32 V.
VBST should be programmed to a value 5.0 V greater than the largest peak voltage expected in the system to
allow adequate amplifier headroom. Since the programming range for the boost voltage extends to 105 V, the
leakage current through the resistor divider can become significant. It is recommended that the sum of the
resistance of R1 and R2 be greater than 400 k
allow adequate amplifier headroom. Since the programming range for the boost voltage extends to 105 V, the
leakage current through the resistor divider can become significant. It is recommended that the sum of the
resistance of R1 and R2 be greater than 400 k
Ω. Note that when resistor values greater than 1 MΩ are used,
PCB contamination may cause boost voltage inaccuracy. Exercise caution when soldering large resistances, and
clean the area when finished for best results.
clean the area when finished for best results.
R1
R2
GAIN[1:0]
V
BST
Full Scale Peak Voltage (V)
402 k
Ω
18.2 k
Ω
00
30
25
392 k
Ω
9.76 k
Ω
01
55
50
768 k
Ω
13 k
Ω
10
80
75
768 k
Ω
9.76 k
Ω
11
105
100
14
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