CH101
Ultra-low Power Integrated Ultrasonic Time-of-Flight Range Sensor
CH101 HIGHLIGHTSAPPLICATIONSThe CH101 is a miniature, ultra-low-power ultrasonic Time-ofFlight (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 aminiature, reflowable package. The SoC runs Chirp’s
advanced ultrasonic DSP algorithms and includes anintegrated 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, andprovides millimeter-accurate range measurements
independent of the target’s color and optical transparency.
The sensor’s Field-of-View (FoV) can be customized andenables simultaneous range measurements to multiple
objects in the FoV. Many algorithms can further process therange 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 fortransmit and receive of ultrasonic pulses. The CH101-02ABR isa 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 INFORMATIONPART 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

Chirp Microsystems reserves the right to change
specifications and information herein without notice.

•
•
•
•
•
•
•

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 fullsunlight to complete darkness• Insensitive to object color, detects opticallytransparent 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 ultrasoundfirmware• 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)

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: 1.4
Release Date: 12/23/2020

CH101
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 ...................................................................................................................................................................... 11Interfacing 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

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CH101SIMPLIFIED BLOCK DIAGRAM

Figure 1. Simplified Block Diagram

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CH101
ABSOLUTE MAXIMUM RATINGSPARAMETER

MIN.
-0.3

AVDD to VSS
VDD to VSS
SDA, SCL, PROG, RST_N to VSS
Electrostatic Discharge (ESD)
Human Body Model (HBM)(1)
Charge Device Model (CDM)(2)LatchupTemperature, Operating
Relative Humidity, Storage
Continuous Input Current (Any Pin)
Soldering Temperature (reflow)

MAX.
2.2

UNIT
V

-0.3
-0.3

2.2
2.2

V
V

-2
-500
-100
-40

2
500
100
85
90
20
260

kV
V
mA
°C
%RH
mA
°C

-20
Table 1. Absolute Maximum Ratings

Notes:
1.
2.

HBM Tests conducted in compliance with ANSI/ESDA/JEDEC JS-001-2014 Or JESD22-A114E
CDM Tests conducted in compliance with JESD22-C101

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TYP.

CH101
PACKAGE INFORMATION
8-PIN LGADESCRIPTION
CH101 Mechanical Integration Guide
CH101 and CH201 Ultrasonic Transceiver Handling andAssembly Guidelines

DOCUMENT NUMBER
AN-000158
AN-000159

Table 2. 8-Pin LGAPIN CONFIGURATION
Top View

Figure 2. Pin Configuration (Top View)

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CH101PIN DESCRIPTIONS
PIN
1
2
3
4
5
6

NAME
INT
SCL
SDA
PROG
VSS
VDD

7

AVDD

8

RESET_NDESCRIPTIONInterrupt output. Can be switched to input for triggering and calibration functions
SCL Input. I2C clock input. This pin must be pulled up externally.
SDA Input/Output. I2C data I/O. This pin must be pulled up externally.
Program Enable. Cannot be floating.
Power return.
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.
Analog Power Supply. Connect to externally regulated supply. Bypass with a 0.1μF
capacitor as close as possible to AVDD I/O pad.
Active-low reset. Cannot be floating.
Table 3. Pin Descriptions

PACKAGE DIMENSIONS

Figure 3. Package Dimensions

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CH101
ELECTRICAL CHARACTERISTICS
AVDD = VDD = 1.8VDC, VSS = 0V, TA = +25°C, min/max are from TA = -40°C to +85°C, unless otherwise specified.
PARAMETERSYMBOL

Analog Power Supply
Digital Power Supply

AVDD
VDD

CONDITIONSPOWER SUPPLY

MIN

TYP

MAX

UNITS

1.62
1.62
ULTRASONIC TRANSMIT CHANNEL

1.8
1.8

1.98
1.98

V
V

Operating Frequency

175
TXRX OPERATION (GPR FIRMWARE USED UNLESS OTHERWISE SPECIFIED)

Maximum Range

Max Range

Minimum Range
Measuring Rate (Sample/sec)

Min RangeSR

Field of View
Current Consumption (AVDD +VDD)Range Noise
Measurement Time
Programming Time

Wall Target
58 mm Diameter Post

1.2(1)
0.7

Short-Range F/W used

4(2)

NR

Configurable up to 180º
SR=1S/s, Range=10 cm
SR=1S/s, Range=1.0m
SR=30S/s, Range=10 cm
SR=30S/s, Range=1.0m
Target range = 30 cm
1m max range

13
15
20
50
1.0
18
60

Table 4. Electrical Characteristics
Notes:
1.
2.

Tested with a stationary target.
For non-stationary objects. While objects closer than 4cm can be detected, the range measurement is not ensured.

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m
m

100

FoV
IS

kHz

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cm
S/s
deg
μA
μA
μA
μA
mm, rmsms
msCH101
ELECTRICAL CHARACTERISTICS (CONT’D)
AVDD = VDD = 1.8VDC, VSS = 0V, TA = +25°C, unless otherwise specified.
PARAMETER
Output Low Voltage
Output High Voltage
I2C Input Voltage Low
I2C Input Voltage HighPin Leakage Current
SCL Clock Frequency

SYMBOL

CONDITIONSMINDIGITAL I/O CHARACTERISTICS
VOL
SDA, INT,
VOH
INT
0.9*VVDD
VIL_I2C
SDA, SCL
VIH_I2C
SDA, SCL
0.7*VVDD
SDA,SCL, INT(Inactive),IL
TA=25°C
DIGITAL/I2C TIMING CHARACTERISTICS
fSCL
I2C Fast Mode
Table 5. Electrical Characteristics (Cont’d)Document Number: DS-000331
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TYP

MAX

UNITS

0.4

V
V
V
V
μA

0.3*VVDD
±1

400

kHz

CH101TYPICAL 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

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CH101DETAILED DESCRIPTIONTHEORY OF OPERATIONThe 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 systemon-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 ofusage 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 roundtrip). 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 givemeasurement accuracies within a few percent error.

DEVICE CONFIGURATIONA CH101 program file must be loaded into the on-chip memory at initial power-on. The program, or firmware, is loaded through aspecial I2C interface. Chirp provides a default general-purpose rangefinder (GPR) firmware that is suitable for a wide range ofapplications. This firmware enables autonomous range finding operation of the CH101. It also supports hardware-triggering of theCH101 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 wakeup source. The interrupt pin can be configured to trigger on motion or proximity.

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CH101APPLICATIONSCHIRP 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 driverallows the user to program, configure, trigger, and readout data from the CH101 through use of C function calls without directinteraction with the CH101 I2C registers. The CH101 driver only requires the customer to implement an I/O layer which communicateswith 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 ameasurement 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 thefirst 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 associatedoperating range for smaller targets will be shorter. The range to detect people will be affected by a variety of factors such as aperson’s size, clothing, orientation to the sensor and the sensor’s field-of-view. In general, given these factors, people can bedetected 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 tocommands 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 I 2C master. The CH101 clock stretches before theacknowledge (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 SCLline.
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’ isa 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.

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CH101Figure 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 bypulsing the INT pin. The measurement will start with deterministic latency relative to the rising edge on INT. This mode is mostuseful for synchronizing several CH101 transceivers. The host controller can use the individual INT pins of several transceivers tocoordinate the exact timing.

CH101 BEAM PATTERNSThe acoustic Field of View is easily customizable for the CH101 and is achieved by adding an acoustic housing to the transceiver thatis 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.

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CH101LAYOUT RECOMMENDATIONS:RECOMMENDED PCB FOOTPRINT

Dimensions in mm
Figure 6. Recommended PCB Footprint

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CH101PCB 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

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CH101TYPICAL OPERATING CIRCUITS

Figure 8. Single Transceiver Operation

Figure 9. Multi- Transceiver Operation

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CH101ORDERING INFORMATIONPART NUMBER DESIGNATION

CH101-xxABx
Product Family
CH101 = Ultrasonic ToF Sensor

Shipping Carrier

Product Variant
00AB = Pulse-Echo Product Variant
02AB = Pitch-Catch Product Variant

R = Tape & Reel

Figure 10. Part Number Designation

This datasheet specifies the following part numbers
PART NUMBER

OPERATION

CH101-00ABR

Pulse-Echo

CH101-02ABR

Pitch-Catch

PACKAGE BODY
3.5 mm x 3.5 mm x 1.26 mm
LGA-8L
3.5 mm x 3.5 mm x 1.26 mm
LGA-8L
Table 6. Part Number Designation

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QUANTITY

PACKAGING

1,000

7” Tape and Reel

1,000

7” Tape and Reel

CH101
PACKAGE MARKING

Figure 11. Package Marking

TAPE & REEL SPECIFICATION

Dimensions in mm

Figure 12. Tape & Reel Specification

SHIPPING LABELA 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

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CH101
DEVICE: CH101-XXXXX-X
LOT NO:XXXXXXXXDATE CODE:
QTY:

XXXX

XXXX

Figure 13. Shipping Label

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CH101REVISION HISTORYDATEREVISION

CHANGES

09/30/2019

1.0

Initial Release10/22/2019

1.1

Changed CH-101 to CH101. Updated figure 7 to current markings.

07/17/2020

1.2

Format Update. Incorporated “Maximum Ratings Table” and “Use of Level
Shifters” section.

09/22/2020

1.3

Fixed minor typos

12/23/2020

1.4

Updated Package Dimensions with tolerances

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CH101This 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 thisdocument. Chirp Microsystems assumes no responsibility for any claims or damages arising from information contained in thisdocument, 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 massdestructive 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, disasterprevention 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 therespective companies with which they are associated.

©2020 Chirp Microsystems. All rights reserved.

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