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首页TI PGA460-Q1:集成超声波解决方案,满足AEC-Q100标准
TI PGA460-Q1:集成超声波解决方案,满足AEC-Q100标准
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更新于2024-06-28
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TI-PGA460-Q1是一款专为汽车行业设计的高性能超声波处理器和传感器驱动器,它提供了全面集成的解决方案,满足了严格的AEC-Q100标准。该芯片具备以下几个关键特性: 1. 温度适应性:工作温度范围宽广,从-40℃到+105℃,确保在极端环境下稳定运行。 2. 电磁兼容性:通过HBMESD和CDMESD分类等级,确保设备在电磁干扰环境中的可靠性能。 3. 驱动器灵活性:内置可配置电流限制的互补低侧驱动器,支持基于变压器的和直接驱动两种拓扑,适应不同类型的传感器。 4. 信号处理能力:支持单个传感器的突发/侦听模式,以及接收器具有6点可编程时变增益,用于低噪声接收和回波包络检测。 5. 智能检测功能:具有12点时变阈值,用于物体检测,并集成定时器用于测量多回声距离和时长。 6. 内置传感器监控:包括温度传感器和诊断功能,如衰减频率和时间、励磁电压监测,有助于系统健康管理和故障诊断。 7. 存储和通信接口:128字节RAM用于回声记录,42字节用户EEPROM用于存储快速初始化配置,支持1线高电压时间和USART异步通信接口,以及CMOS电平的USART接口,便于数据传输和交互。 8. 广泛的应用场景:PGA460-Q1适用于多种汽车安全与便利功能,如超声波雷达、停车辅助、车道偏离警告、物体距离和位置感知、存在和接近检测,以及无人机和机器人着陆辅助中的障碍物识别。 这款芯片的这些特性使其成为现代汽车电子系统中不可或缺的组件,能有效提升车辆的安全性和驾驶体验。在设计和使用时,应确保参考最新的英文数据手册SLASEC8获取最准确的技术信息。
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![](https://csdnimg.cn/release/download_crawler_static/87242467/bg10.jpg)
AFE
GAIN
t
Initial Gain
(0, GAIN_INIT)
TVG Start Time
(TVG_T0, GAIN_INIT)
TVG Point 1
(TVG_T1, TVG_G1)
TVG Point 2
(TVG_T2, TVG_G2)
TVG Point 3
(TVG_T3, TVG_G3)
TVG Point 4
(TVG_T4, TVG_G4)
TVG Point 5
(TVG_T5, TVG_G5)
End of Record Time
(P1_REC or P2_REC)
0.5 dB
16
PGA460-Q1
ZHCSFZ7B –FEBRUARY 2017 –REVISED JANUARY 2019
www.ti.com.cn
版权 © 2017–2019, Texas Instruments Incorporated
Feature Description (接接下下页页)
图图 6. Time-Varying Gain Assignment Example
The time value, TVG start time, is expressed in terms of absolute time, and all following TVG point times
(TVG_Tx parameters) are expressed as a delta time between the current and previous point. All gain values are
expressed in an absolute gain value in dB and are unrelated from each other. The final gain setting of TVG Point
5 (TVG_G5) will be kept constant until the end of the echo record time. The time-varying gain assignment is the
same for both presets. A linear interpolation scheme is used to calculate gain between two TVG points. The AFE
gain resolution is 0.5 dB typical.
注注
The time-varying gain changes during the recording are applied only on the record cycle
that follows. If the TVGAIN[0:6] registers programmed to 0x00, the time-varying gain
function of the PGA460-Q1 device is disabled and a fixed gain defined by the INIT_GAIN
register is applied. In this case, changing the INIT_GAIN register changes the gain of AFE
during the recording.
The offset on the time-varying gain is controlled through the two AFE_GAIN_RNG bits in DECPL_TEMP register.
For each of the four settings as defined in the Register Maps section, the gain can be varied from 0 to 32 dB
added on top of the offset.
7.3.4 Digital Signal Processing
The DSP block of the PGA460-Q1 device processes the digital data from the ADC to extract the peak profile of
the echo after which the output of the DSP is compared against the programmed threshold to measure the time
of flight for object distance calculation.
图 7 shows the data path of the DSP. Also, the output of the comparator can be deglitched by the
THR_CMP_DEGLTCH[7:4] bits in the DEADTIME register.
![](https://csdnimg.cn/release/download_crawler_static/87242467/bg11.jpg)
Digital Signal Processing (DSP)²Ultrasonic Echo
From ADC
12
De-mux
Digital Signal Processing (DSP)²Temperature
16-sample
Averager
Scaling
(gain, offset)
8MSB
Digital
Gain
Nonlinear
Scaling
Low-Pass
Filter
RectifierBand-Pass
Filter
Peak Hold
To temperature
diagnostic
+
±
To UART
Object Timer
To TCI-IO
Pin Control
Mux
Memory
Preset 1
Threshold
Map
Memory
Preset 2
Threshold
Map
+
±
To decay time
diagnostics
SAT_TH
PGA460-Q1
www.ti.com.cn
ZHCSFZ7B –FEBRUARY 2017 –REVISED JANUARY 2019
17版权 © 2017–2019, Texas Instruments Incorporated
图图 7. DSP Data-Path
![](https://csdnimg.cn/release/download_crawler_static/87242467/bg12.jpg)
Scale _Exponent
if (t Time_Offset)
Output Input;
else
Output (Input Noise_Level) ;
18
PGA460-Q1
ZHCSFZ7B –FEBRUARY 2017 –REVISED JANUARY 2019
www.ti.com.cn
版权 © 2017–2019, Texas Instruments Incorporated
7.3.4.1 Ultrasonic Echo—Band-Pass Filter
The ultrasonic echo signal is an amplitude-modulated signal with an underlying carrier frequency equal to the
drive frequency of the ultrasonic transducer. The DSP band-pass filter block allows the frequencies outside of the
observed frequency band to be filtered out and therefore reducing the amount of noise influencing the ultrasonic
echo signal.
The center frequency of the filter is automatically adjusted based on the driving frequency set by the FREQ bit
while the bandwidth of the filter can be adjusted from 2 kHz to 8 kHz in steps of 2 kHz by setting the BPF_BW bit
in the INIT_GAIN EEPROM register.
The band-pass filter is a second-order Butterworth IIR type filter. On power up, the PGA460-Q1 device calculates
the coefficients and places them in the BPF_A2_xSB, BPF_A3_xSB, and BPF_B1_xSB registers. These
registers can be overwritten by the user to reconfigure the filter. However, if the FREQ or BPF_BW bit is
changed, the coefficient calculation sequence is rerun and the device rewrites these registers. In case the
FREQ_SHIFT bit is set to 1 (80- to 480-kHz driving frequency range), the band-pass filter coefficients are not
calculated automatically by the PGA460-Q1 device. In this case the MCU is required to write these values
through the UART or USART interface.
7.3.4.2 Ultrasonic Echo–Rectifier, Peak Hold, Low-Pass Filter, and Data Selection
The rectifier, peak extractor, and low-pass filter DSP blocks demodulate the echo signal while outputting a base-
band representation to be compared against the programmed thresholds. These blocks are defined as:
Rectifier This block outputs the absolute value of the input signal since the input signal can be positive and
negative in amplitude.
Peak hold This block holds the peak value of the rectified signal for a specific amount of time required for the
low-pass filter to detect the peak amplitude of the signal.
Low-pass filter (LPF) This block removes any noise artifacts from the echo signal. The LPF is realized as a
first-order IIR type filter. The user can set the cutoff frequency by setting the LPF_CO bit in
CURR_LIM_P2 register from 1 kHz to 4 kHz with a step of 1 kHz.
On power up the PGA460-Q1 device calculates the values of the filter coefficients and places them in the
LPF_A2_xSB and LPF_B1_xSB registers, respectively. The user can overwrite the values in these registers and
reconfigure the filter. In this case, the PGA460-Q1 device does not take any action. However, if the LPF_CO bit
is changed, the coefficient calculation sequence must be rerun and the device repopulates these registers.
7.3.4.3 Ultrasonic Echo—Nonlinear Scaling
The nonlinear scaling block in the DSP data path provides exponential scaling (digital nonlinear amplification) for
the echo signal to achieve a higher SNR. This feature is useful for detecting long distance object where the
amplitude of the echo signal is very attenuated and close to the noise floor.
The nonlinear scaling block performs the following algorithm:
where
• t is the current record time.
• Time_Offset is set by the SCALE_N parameter and is used to select one of the time points corresponding to
threshold points, TH9, TH10, TH11, or TH12 defined in the Ultrasonic Echo—Threshold Data Assignment
section.
• Scale_Exponent is the nonlinear exponent (1.5 or 2) and defined by the SCALE_K bit.
• Noise_Level is the user-set noise level between 0 and 31 in 1 LSB step and defined by the NOISE_LVL bit. (3)
The SCALE_N, SCALE_K, and NOISE_LVL bits are EEPROM parameters in the DSP_SCALE register.
![](https://csdnimg.cn/release/download_crawler_static/87242467/bg13.jpg)
Threshold
Level
t
(TH_Px_T1,
TH_Px_L1)
End of Record Time
(Px_REC)
0
8
247
255
239
16
24
±8
. . . . . . . . . . . . . . . . . . . . . . . . . .
Offset Adjustment Range (TH_Px_OFF)
(TH_Px_T2,
TH_Px_L2)
(TH_Px_T3,
TH_Px_L3)
(TH_Px_T4,
TH_Px_L4)
(TH_Px_T5,
TH_Px_L5)
(TH_Px_T6,
TH_Px_L6)
(TH_Px_T7,
TH_Px_L7)
(TH_Px_T8,
TH_Px_L8)
(TH_Px_T9,
TH_Px_L9)
(TH_Px_T10,
TH_Px_L10)
(TH_Px_T11,
TH_Px_L11)
(TH_Px_T12,
TH_Px_L12)
Initial
Segment
I II III
+7
±8
19
PGA460-Q1
www.ti.com.cn
ZHCSFZ7B –FEBRUARY 2017 –REVISED JANUARY 2019
版权 © 2017–2019, Texas Instruments Incorporated
注注
The nonlinear scaling block can be applied to Preset1 and Preset2.
7.3.4.4 Ultrasonic Echo—Threshold Data Assignment
The PGA460-Q1 threshold assignments are organized in two presets: Preset1 and Preset2. Both of these
presets have an independent memory map for threshold segment allocation. The PGA460-Q1 device supports
up to 12 threshold segments for each preset defined by the threshold segment points (TSP) in the
P1_THR_[0:15] registers for Preset1 and P2_THR_[0:15]registers for Preset2.
图 8 shows an example of a threshold assignment.
图图 8. Threshold Assignment Example
As shown in 图 8, each TSP is described in the (time, level) format while Px is the preset number (P1 for
Preset1, P2 for Preset2). Additionally, only the initial segment time parameter (TH_Px_T1) value is expressed in
terms of absolute time, while all following TSP times (TH_Px_Tx parameters) are expressed as a delta time
between the absolute time value of the previous TSP and the absolute time value of the current TSP. The level
values of each TSP (TH_Px_Lx parameters) are all expressed in an absolute LSB-level value and are unrelated
from each other. The TSP level threshold value at any given time moment is determined by the PGA460-Q1
device as a linear interpolation function between the two neighboring threshold segment points
As shown in 图 8, the initial segment has a constant threshold value determined by the TH_Px_L1 parameter
until reaching the start of the first segment and also the 12th segment will have a constant threshold value
determined by the TH_Px_L12 parameter until reaching the end of record time defined by the Px_REC
parameter.
The TH_Px_L1 through TH_Px_L8 threshold parameters are 5-bits wide and the TH_Px_L9 through TH_Px_L12
parameters are 8-bits wide. These sizes help save memory space and at the same time allow higher resolution
for long-range detection of weak echo signals in presence of noise while keeping the range constant across all
TSPs. Because the TH_Px_L1 through TH_Px_L8 resolution is an 8 LSB, a threshold offset is defined to allow
finer adjustment of the threshold map for short-range detection.
![](https://csdnimg.cn/release/download_crawler_static/87242467/bg14.jpg)
20
PGA460-Q1
ZHCSFZ7B –FEBRUARY 2017 –REVISED JANUARY 2019
www.ti.com.cn
版权 © 2017–2019, Texas Instruments Incorporated
注注
• All calculated values of TSP after adding offset, if negative, are clamped to 0 before
linear interpolation which causes the slope of threshold curve to deviate from expected
value.
• Both Preset1 and Preset2 threshold map parameters are protected by a CRC
calculation algorithm (公式 6).
• At power up or wakeup from low power mode, all threshold registers (Px_THR_XX)
and threshold CRC register (THR_CRC) are not initialized to the default value which
causes a CRC error and sets THR_CRC_ERR bit to 1. This occurrence indicates to
the MCU that the configuration is not loaded properly. Writing to threshold registers
reruns CRC calculation and updates the error bit.
7.3.4.5 Digital Gain
A digital gain feature after the low-pass filtering is implemented to improve the SNR of the received echo without
lowering the threshold values. Because this gain is applied after the band-pass and low-pass filtering, the digital
gain does not amplify the out of band noise. This gain feature can help in suppressing false detection such as
ground reflection and detecting farther objects with more accuracy.
Two sets of digital gain ranges are available: short range (SR) and long range (LR). The SR and LR gain levels
are set using the Px_DIG_GAIN_SR and Px_DIG_GAIN_LR parameters, respectively, in the Px_GAIN_CTRL
register independently for Preset1 and Preset2. The LR gain is applied starting from the threshold level point set
by Px_DIG_GAIN_LR_ST parameter to the end of the record period. The SR gain is applied from time zero to
the start of the selected LR-threshold level point.
To prevent false detection of an echo at the point in time where the digital gain is applied, the defined thresholds
are also changed as shown in the example plot in 图 9. Here, the LR gain is applied starting from the threshold
level point 9. If the LR gain is different than the SR gain at threshold level point 8, the threshold level 8 is
multiplied by the ratio between the LR gain and SR gain (DIG_GAIN_LR/DIG_GAIN_SR) 1 µs after the end of
the SR threshold level 9 point. Although this creates a discontinuity in the threshold level, the object detection is
not affected (a false threshold crossing is prevented) because the echo signal is also scaled by the same gain
ratio. After this point, the threshold level is changed to the next set threshold level (point 9 in example below)
using a linear interpolation scheme. The threshold levels should be adjusted by taking the digital gain and the
ratio between the LR and SR gains into account.
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