CH101
Ultra-low Power Integrated Ultrasonic Time-of-Flight Range Sensor
Chirp Microsystems reserves the right to change
specifications and information herein without notice.
Chirp Microsystems
2560 Ninth Street, Ste 200, Berkeley, CA 94710 U.S.A
+1(510) 640–8155
www.chirpmicro.com
Document Number: DS-000331
Revision: 1.2
Release Date: 07/17/2020
CH101 HIGHLIGHTS
The CH101 is a miniature, ultra-low-power ultrasonic Time-of-
Flight (ToF) range sensor. Based on Chirp’s patented MEMS
technology, the CH101 is a system-in-package that integrates
a PMUT (Piezoelectric Micromachined Ultrasonic Transducer)
together with an ultra-low-power SoC (system on chip) in a
miniature, reflowable package. The SoC runs Chirp’s
advanced ultrasonic DSP algorithms and includes an
integrated microcontroller that provides digital range
readings via I2C.
Complementing Chirp’s long-range CH201 ultrasonic ToF
sensor product, the CH101 provides accurate range
measurements to targets at distances up to 1.2m. Using
ultrasonic measurements, the sensor works in any lighting
condition, including full sunlight to complete darkness, and
provides millimeter-accurate range measurements
independent of the target’s color and optical transparency.
The sensor’s Field-of-View (FoV) can be customized and
enables simultaneous range measurements to multiple
objects in the FoV. Many algorithms can further process the
range information for a variety of usage cases in a wide range
of applications.
The CH101-00ABR is a Pulse-Echo product intended for range
finding and presence applications using a single sensor for
transmit and receive of ultrasonic pulses. The CH101-02ABR is
a frequency matched Pitch-Catch product intended for
applications using one sensor for transmit and a second
sensor for receiving the frequency matched ultrasonic pulse.
DEVICE INFORMATION
PART NUMBER
OPERATION
PACKAGE
CH101-00ABR
Pulse-Echo
3.5 x 3.5 x 1.26mm LGA
CH101-02ABR
Pitch-Catch
3.5 x 3.5 x 1.26mm LGA
RoHS and Green-Compliant Package
APPLICATIONS
• Augmented and Virtual Reality
• Robotics
• Obstacle avoidance
• Mobile and Computing Devices
• Proximity/Presence sensing
• Ultra-low power remote presence-sensing nodes
• Home/Building automation
FEATURES
• Fast, accurate range-finding
• Operating range from 4 cm to 1.2m
• Sample rate up to 100 samples/sec
• 1.0 mm RMS range noise at 30 cm range
• Programmable modes optimized for medium
and short-range sensing applications
• Customizable field of view (FoV) up to 180°
• Multi-object detection
• Works in any lighting condition, including full
sunlight to complete darkness
• Insensitive to object color, detects optically
transparent surfaces (glass, clear plastics, etc.)
• Easy to integrate
• Single sensor for receive and transmit
• Single 1.8V supply
• I2C Fast-Mode compatible interface, data rates
up to 400 kbps
• Dedicated programmable range interrupt pin
• Platform-independent software driver enables
turnkey range-finding
• Miniature integrated module
• 3.5 mmx 3.5 mm x 1.26 mm, 8-pin LGA package
• Compatible with standard SMD reflow
• Low-power SoC running advanced ultrasound
firmware
• Operating temperature range: -40°C to 85°C
• Ultra-low supply current
• 1 sample/s:
o 13 µA (10 cm max range)
o 15 µA (1.0 m max range)
• 30 samples/s:
o 20 µA (10 cm max range)
o 50 µA (1.0 m max range)
CH101
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Table of Contents
CH101 Highlights ........................................................................................................................................................................................ 1
Device Information .................................................................................................................................................................................... 1
Applications ............................................................................................................................................................................................... 1
Features ..................................................................................................................................................................................................... 1
Simplified Block Diagram ................................................................................................................................................................... 3
Absolute Maximum Ratings ............................................................................................................................................................... 4
Package Information .......................................................................................................................................................................... 5
8-Pin LGA .................................................................................................................................................................................... 5
Pin Configuration ....................................................................................................................................................................... 5
Pin Descriptions ......................................................................................................................................................................... 6
Package Dimensions .................................................................................................................................................................. 6
Electrical Characteristics .................................................................................................................................................................... 7
Electrical Characteristics (Cont’d) ...................................................................................................................................................... 8
Typical Operating Characteristics ...................................................................................................................................................... 9
Detailed Description ........................................................................................................................................................................ 10
Theory of Operation ................................................................................................................................................................. 10
Device Configuration ................................................................................................................................................................ 10
Applications ..................................................................................................................................................................................... 11
Chirp CH101 Driver .................................................................................................................................................................. 11
Object Detection ...................................................................................................................................................................... 11
Interfacing to the CH101 Ultrasonic Sensor ............................................................................................................................. 11
Device Modes of Operation: .................................................................................................................................................... 12
Layout Recommendations: ...................................................................................................................................................... 13
PCB Reflow Recommendations: ............................................................................................................................................... 14
Use of Level Shifters ................................................................................................................................................................. 14
Typical Operating Circuits ................................................................................................................................................................ 15
Ordering Information ................................................................................................................................................................... 16
Part Number Designation ........................................................................................................................................................ 16
Package Marking ...................................................................................................................................................................... 17
Tape & Reel Specification ........................................................................................................................................................ 17
Shipping Label .......................................................................................................................................................................... 17
Revision History ........................................................................................................................................................................... 19
CH101
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Revision: 1.2
SIMPLIFIED BLOCK DIAGRAM
Figure 1. Simplified Block Diagram
CH101
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ABSOLUTE MAXIMUM RATINGS
PARAMETER
TYP.
MAX.
UNIT
AVDD to VSS
2.2
V
VDD to VSS
2.2
V
SDA, SCL, PROG, RST_N to VSS
2.2
V
Electrostatic Discharge (ESD)
Human Body Model (HBM)(1)
Charge Device Model (CDM)
(2)
-2
2
500
kV
V
Latchup
100
mA
Temperature, Operating
85
°C
Relative Humidity, Storage
90
%RH
Continuous Input Current (Any Pin)
20
mA
Soldering Temperature (reflow)
260
°C
Table 1. Absolute Maximum Ratings
Notes:
1. HBM Tests conducted in compliance with ANSI/ESDA/JEDEC JS-001-2014 Or JESD22-A114E
2. CDM Tests conducted in compliance with JESD22-C101
CH101
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PACKAGE INFORMATION
8-PIN LGA
DESCRIPTION
DOCUMENT NUMBER
CH101 Mechanical Integration Guide
AN-000158
CH101 and CH201 Ultrasonic Transceiver Handling and
Assembly Guidelines
AN-000159
Table 2. 8-Pin LGA
PIN CONFIGURATION
Top View
Figure 2. Pin Configuration (Top View)
CH101
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PIN DESCRIPTIONS
PIN
NAME
DESCRIPTION
1
INT
Interrupt output. Can be switched to input for triggering and calibration functions
2
SCL
SCL Input. I2C clock input. This pin must be pulled up externally.
3
SDA
SDA Input/Output. I2C data I/O. This pin must be pulled up externally.
4
PROG
Program Enable. Cannot be floating.
5
VSS
Power return.
6
VDD
Digital Logic Supply. Connect to externally regulated 1.8V supply. Suggest common
connection to AVDD. If not connected locally to AVDD, bypass with a 0.1μF capacitor as
close as possible to VDD I/O pad.
7
AVDD
Analog Power Supply. Connect to externally regulated supply. Bypass with a 0.1μF
capacitor as close as possible to AVDD I/O pad.
8
RESET_N
Active-low reset. Cannot be floating.
Table 3. Pin Descriptions
PACKAGE DIMENSIONS
Figure 3. Package Dimensions
CH101
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ELECTRICAL CHARACTERISTICS
AVDD = VDD = 1.8VDC, VSS = 0V, TA = +25°C, min/max are from TA = -40°C to +85°C, unless otherwise specified.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLY
Analog Power Supply
AVDD
1.62
1.8
1.98
V
Digital Power Supply
VDD
1.62
1.8
1.98
V
ULTRASONIC TRANSMIT CHANNEL
Operating Frequency
175
kHz
TXRX OPERATION (GPR FIRMWARE USED UNLESS OTHERWISE SPECIFIED)
Maximum Range Max Range Wall Target
58 mm Diameter Post 1.2(1)
0.7
m
m
Minimum Range
Min Range
Short-Range F/W used
4(2)
cm
Measuring Rate (Sample/sec)
SR
100
S/s
Field of View FoV Configurable up to 180º deg
Current Consumption (AVDD +
VDD) IS
SR=1S/s, Range=10 cm
SR=1S/s, Range=1.0m
SR=30S/s, Range=10 cm
SR=30S/s, Range=1.0m
13
15
20
50
μA
μA
μA
μA
Range Noise
NR
Target range = 30 cm
1.0
mm, rms
Measurement Time
1m max range
18
ms
Programming Time
60
ms
Table 4. Electrical Characteristics
Notes:
1. Tested with a stationary target.
2. For non-stationary objects. While objects closer than 4cm can be detected, the range measurement is not ensured.
CH101
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ELECTRICAL CHARACTERISTICS (CONT’D)
AVDD = VDD = 1.8VDC, VSS = 0V, TA = +25°C, unless otherwise specified.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DIGITAL I/O CHARACTERISTICS
Output Low Voltage
VOL
SDA, INT,
0.4
V
Output High Voltage
VOH
INT
0.9*VVDD
V
I2C Input Voltage Low
VIL_I2C
SDA, SCL
0.3*VVDD
V
I2C Input Voltage High
VIH_I2C
SDA, SCL
0.7*VVDD
V
Pin Leakage Current IL
SDA,SCL, INT(Inactive),
TA=25°C
±1
μA
DIGITAL/I2C TIMING CHARACTERISTICS
SCL Clock Frequency
fSCL
I2C Fast Mode
400
kHz
Table 5. Electrical Characteristics (Cont’d)
CH101
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TYPICAL OPERATING CHARACTERISTICS
AVDD = VDD = 1.8VDC, VSS = 0V, TA = +25°C, unless otherwise specified.
Typical Beam Pattern – MOD_CH101-03-01 Omnidirectional FoV module
(Measured with a 1m2 flat plate target at a 30 cm range)
Figure 4. Beam pattern measurements of CH101 module
CH101
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DETAILED DESCRIPTION
THEORY OF OPERATION
The CH101 is an autonomous, digital output ultrasonic rangefinder. The Simplified Block Diagram, previously shown, details the main
components at the package-level. Inside the package are a piezoelectric micro-machined ultrasonic transducer (PMUT) and system-
on-chip (SoC). The SoC controls the PMUT to produce pulses of ultrasound that reflect off targets in the sensor’s Field of View (FoV).
The reflections are received by the same PMUT after a short time delay, amplified by sensitive electronics, digitized, and further
processed to produce the range to the primary target. Many algorithms can further process the range information for a variety of
usage cases in a wide range of applications.
The time it takes the ultrasound pulse to propagate from the PMUT to the target and back is called the time-of-flight (ToF). The
distance to the target is found by multiplying the time-of-flight by the speed of sound and dividing by two (to account for the round-
trip). The speed of sound in air is approximately 343 m/s. The speed of sound is not a constant but is generally stable enough to give
measurement accuracies within a few percent error.
DEVICE CONFIGURATION
A CH101 program file must be loaded into the on-chip memory at initial power-on. The program, or firmware, is loaded through a
special I2C interface. Chirp provides a default general-purpose rangefinder (GPR) firmware that is suitable for a wide range of
applications. This firmware enables autonomous range finding operation of the CH101. It also supports hardware-triggering of the
CH101 for applications requiring multiple transceivers. Program files can also be tailored to the customer’s application. Contact
Chirp for more information.
CH101 has several features that allow for low power operation. An ultra-low-power, on-chip real-time clock (RTC) sets the sample
rate and provides the reference for the time-of-flight measurement. The host processor does not need to provide any stimulus to
the CH101 during normal operation, allowing the host processor to be shut down into its lowest power mode until the CH101
generates a wake-up interrupt. There is also a general-purpose input/output (INT) pin that is optimized to be used as a system wake-
up source. The interrupt pin can be configured to trigger on motion or proximity.
CH101
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APPLICATIONS
CHIRP CH101 DRIVER
Chirp provides a compiler and microcontroller-independent C driver for the CH101 which greatly simplifies integration. The CH101
driver implements high-level control of one or more CH101s attached to one or more I2C ports on the host processor. The CH101 driver
allows the user to program, configure, trigger, and readout data from the CH101 through use of C function calls without direct
interaction with the CH101 I2C registers. The CH101 driver only requires the customer to implement an I/O layer which communicates
with the host processor’s I2C hardware and GPIO hardware. Chirp highly recommends that all designs use the CH101 driver.
OBJECT DETECTION
Detecting the presence of objects or people can be optimized via software, by setting the sensor’s full-scale range (FSR), and via
hardware, using an acoustic housing to narrow or widen the sensor’s field-of-view. The former means that the user may set the
maximum distance at which the sensor will detect an object. FSR values refer to the one-way distance to a detected object.
In practice, the FSR setting controls the amount of time that the sensor spends in the listening (receiving) period during a
measurement cycle. Therefore, the FSR setting affects the time required to complete a measurement. Longer full-scale range values
will require more time for a measurement to complete.
Ultrasonic signal processing using the CH101’s General Purpose Rangefinder (GPR) Firmware will detect echoes that bounce off the
first target in the Field-of-View. The size, position, and material composition of the target will affect the maximum range at which
the sensor can detect the target. Large targets, such as walls, are much easier to detect than smaller targets. Thus, the associated
operating range for smaller targets will be shorter. The range to detect people will be affected by a variety of factors such as a
person’s size, clothing, orientation to the sensor and the sensor’s field-of-view. In general, given these factors, people can be
detected at a maximum distance of 0.7m from the CH101 sensor.
For additional guidance on the detection of people/objects using the NEMA standard, AN-000214 Presence Detection Application
Note discusses the analysis of presence detection using the Long-Range CH201 Ultrasonic sensor.
INTERFACING TO THE CH101 ULTRASONIC SENSOR
The CH101 communicates with a host processor over the 2-wire I2C protocol. The CH101 operates as an I2C slave and responds to
commands issued by the I2C master.
The CH101 contains two separate I2C interfaces, running on two separate slave addresses. The first is for loading firmware into the
on-chip program memory, and the second is for in-application communication with the CH101. The 7-bit programming address is
0x45, and the 7-bit application address default is 0x29. The application address can be reprogrammed to any valid 7-bit I2C address.
The CH101 uses clock stretching to allow for enough time to respond to the I2C master. The CH101 clock stretches before the
acknowledge (ACK) bit on both transmit and receive. For example, when the CH101 transmits, it will hold SCL low after it transmits
the 8th bit from the current byte while it loads the next byte into its internal transmit buffer. When the next byte is ready, it releases
the SCL line, reads the master’s ACK bit, and proceeds accordingly. When the CH101 is receiving, it holds the SCL line low after it
receives the 8th bit in a byte. The CH101 then chooses whether to ACK or NACK depending on the received data and releases the SCL
line.
The figure below shows an overview of the I2C slave interface. In the diagram, ‘S’ indicates I2C start, ‘R/W’ is the read/write bit, ‘Sr’ is
a repeated start, ‘A’ is acknowledge, and ‘P’ is the stop condition. Grey boxes indicate the I2C master actions; white boxes indicate
the I2C slave actions.
CH101
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Figure 5. CH101 I2C Slave Interface Diagram
DEVICE MODES OF OPERATION:
FREE-RUNNING MODE
In the free-running measurement mode, the CH101 runs autonomously at a user specified sample rate. In this mode, the INT pin is
configured as an output. The CH101 pulses the INT pin high when a new range sample is available. At this point, the host processor
may read the sample data from the CH101 over the I2C interface.
HARDWARE-TRIGGERED MODE
In the hardware triggered mode, the INT pin is used bi-directionally. The CH101 remains in an idle condition until triggered by
pulsing the INT pin. The measurement will start with deterministic latency relative to the rising edge on INT. This mode is most
useful for synchronizing several CH101 transceivers. The host controller can use the individual INT pins of several transceivers to
coordinate the exact timing.
CH101 BEAM PATTERNS
The acoustic Field of View is easily customizable for the CH101 and is achieved by adding an acoustic housing to the transceiver that
is profiled to realize the desired beam pattern. Symmetric, asymmetric, and omnidirectional (180° FoV) beam patterns are realizable.
An example beam pattern is shown in the Typical Operating Characteristics section of this document and several acoustic housing
designs for various FoV’s are available from Chirp.
CH101
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LAYOUT RECOMMENDATIONS:
RECOMMENDED PCB FOOTPRINT
Dimensions in mm
Figure 6. Recommended PCB Footprint
CH101
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PCB REFLOW RECOMMENDATIONS:
See App Note AN-000159, CH101 and CH201 Ultrasonic Transceiver Handling and Assembly Guidelines.
USE OF LEVEL SHIFTERS
While the use of autosense level shifters for all the digital I/O signal signals is acceptable, special handling of the INT line while using
a level shifter is required to ensure proper resetting of this line. As the circuit stage is neither a push-pull nor open-drain
configuration (see representative circuit below), it is recommended that level shifter with a manual direction control line be used.
The TI SN74LVC2T45 Bus Transceiver is a recommended device for level shifting of the INT signal line.
Figure 7. INT Line I/O Circuit Stage
CH101
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TYPICAL OPERATING CIRCUITS
Figure 8. Single Transceiver Operation
Figure 9. Multi- Transceiver Operation
CH101
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ORDERING INFORMATION
PART NUMBER DESIGNATION
Figure 10. Part Number Designation
This datasheet specifies the following part numbers
PART NUMBER
OPERATION
PACKAGE BODY
QUANTITY
PACKAGING
CH101-00ABR Pulse-Echo
3.5 mm x 3.5 mm x 1.26 mm
LGA-8L
1,000 7” Tape and Reel
CH101-02ABR Pitch-Catch
3.5 mm x 3.5 mm x 1.26 mm
LGA-8L
1,000 7” Tape and Reel
Table 6. Part Number Designation
CH101-xxABx
Product Family
Product Variant
Shipping Carrier
R = Tape & Reel
00AB = Pulse-Echo Product Variant
02AB = Pitch-Catch Product Variant
CH101 = Ultrasonic ToF Sensor
CH101
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PACKAGE MARKING
Figure 11. Package Marking
TAPE & REEL SPECIFICATION
Figure 12. Tape & Reel Specification
SHIPPING LABEL
A Shipping Label will be attached to the reel, bag and box. The information provided on the label is as follows:
• Device: This is the full part number
• Lot Number: Chirp manufacturing lot number
• Date Code: Date the lot was sealed in the moisture proof bag
• Quantity: Number of components on the reel
• 2D Barcode: Contains Lot No., quantity and reel/bag/box number
Dimensions in mm
CH101
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Figure 13. Shipping Label
DEVICE: CH101-XXXXX-X
LOT NO: XXXXXXXX
DATE CODE: XXXX
QTY: XXXX
CH101
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Revision: 1.2
REVISION HISTORY
DATE REVISION CHANGES
09/30/19 1.0 Initial Release
10/22/19 1.1 Changed CH-101 to CH101. Updated figure 7 to current markings.
07/17/20 1.2 Format Update. Incorporated “Maximum Ratings Table” and “Use of Level
Shifters” section.
CH101
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Revision: 1.2
This information furnished by Chirp Microsystems, Inc. (“Chirp Microsystems”) is believed to be accurate and reliable. However, no
responsibility is assumed by Chirp Microsystems for its use, or for any infringements of patents or other rights of third parties that
may result from its use. Specifications are subject to change without notice. Chirp Microsystems reserves the right to make changes
to this product, including its circuits and software, in order to improve its design and/or performance, without prior notice. Chirp
Microsystems makes no warranties, neither expressed nor implied, regarding the information and specifications contained in this
document. Chirp Microsystems assumes no responsibility for any claims or damages arising from information contained in this
document, or from the use of products and services detailed therein. This includes, but is not limited to, claims or damages based on
the infringement of patents, copyrights, mask work and/or other intellectual property rights.
Certain intellectual property owned by Chirp Microsystems and described in this document is patent protected. No license is granted
by implication or otherwise under any patent or patent rights of Chirp Microsystems. This publication supersedes and replaces all
information previously supplied. Trademarks that are registered trademarks are the property of their respective companies. Chirp
Microsystems sensors should not be used or sold in the development, storage, production or utilization of any conventional or mass-
destructive weapons or for any other weapons or life threatening applications, as well as in any other life critical applications such as
medical equipment, transportation, aerospace and nuclear instruments, undersea equipment, power plant equipment, disaster
prevention and crime prevention equipment.
©2020 Chirp Microsystems. All rights reserved. Chirp Microsystems and the Chirp Microsystems logo are trademarks of Chirp
Microsystems, Inc. The TDK logo is a trademark of TDK Corporation. Other company and product names may be trademarks of the
respective companies with which they are associated.
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