CH201
Long-Range Ultrasonic Time-of-Flight Range Sensor
CH201 HIGHLIGHTSFEATURES

CH201 is a miniature, ultra-low power, long-range ultrasonicTime-of-Flight (ToF) range sensor. Based on Chirp’s patented
MEMS technology, the CH201 is a system-in-package that
integrates a PMUT (Piezoelectric Micromachined UltrasonicTransducer) together with an ultra-low power SoC (System onChip) in a miniature, reflowable package. The SoC runs Chirp’s
advanced ultrasonic DSP algorithms and includes an integrated
microcontroller that provides digital range readings over I2C.

•

Complementing Chirp’s CH101 ultrasonic ToF sensor product,
CH201 provides accurate range measurements to targets at
distances up to 5m. Based on ultrasonic pulse-echomeasurements, the sensor works in any lighting condition,
including full sunlight, and provides millimeter-accurate range
measurements independent of the target’s color and opticaltransparency. The sensor’s Field-Of-View (FOV) can becustomized and enables simultaneous range measurements tomultiple objects in the FOV. Many algorithms can further
process the range information for a variety of usage cases in awide range of applications.

DEVICE INFORMATIONPART NUMBER

PACKAGE

LID OPENING

CH201-00ABR

3.5 x 3.5 x 1.26 mm LGA

1-HoleRoHS and Green-Compliant Package

Fast, accurate range-finding• Operating range from 20 cm to 5m• Programmable modes optimized for long or
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 kHz• Dedicated programmable range interrupt pin• Platform-independent software driver enables
turnkey range-finding• Miniature integrated package• 3.5 mmx 3.5mm x 1.26mm, 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 7.5 µA (1 m max range)o 13.5 µA (5 m max range)• 25 samples/s:o 63 µA (1 m max range)o 247 µA (5 m max range)

APPLICATIONS
•
•
•
•
•
•
•

User presence in Home/Building Automation and
Personal Electronics
Obstacle avoidance
Robotics and Drones
Ultra-low power remote presence-sensing nodes
Augmented/Virtual Reality and Gaming
Gesture control
Liquid level sensing & shelf inventory monitoring

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-000379
Revision: 1.2
Release Date: 01/07/2021

CH201
Table of Contents
CH201 HIGHLIGHTS.................................................................................................................................................................................... 1
DEVICE INFORMATION ................................................................................................................................................................................. 1
APPLICATIONS ............................................................................................................................................................................................ 1
FEATURES .................................................................................................................................................................................................. 1
1

Simplified Block Diagram ...........................................................................................................................................................3
1.1

2

Package Information ..................................................................................................................................................................4
2.1
2.2
2.3
2.4

3

ABSOLUTE MAXIMUM RATINGS ......................................................................................................................................................... 3

8-PIN LGA .................................................................................................................................................................................... 4
PIN CONFIGURATION ....................................................................................................................................................................... 4
PIN DESCRIPTION ............................................................................................................................................................................ 4
PACKAGE DIMENSIONS..................................................................................................................................................................... 5

Electrical Characteristics ............................................................................................................................................................6
3.1

ELECTRICAL CHARACTERISTICS (CONT’D).............................................................................................................................................. 7

4

Typical Operating Characteristics ...............................................................................................................................................85

Detailed Description ..................................................................................................................................................................9
5.1
5.2

6

THEORY OF OPERATION.................................................................................................................................................................... 9
DEVICE CONFIGURATION .................................................................................................................................................................. 9

Applications ............................................................................................................................................................................. 10
6.1
6.2
6.3
6.4

CHIRP CH201 DRIVER ................................................................................................................................................................... 10
OBJECT DETECTION ....................................................................................................................................................................... 10
INTERFACING TO THE CH201 ULTRASONIC SENSOR ........................................................................................................................... 10
DEVICE MODES OF OPERATION ....................................................................................................................................................... 11

Free-Running Mode ............................................................................................................................................................................................... 11
Hardware-Triggered Mode .................................................................................................................................................................................... 11
CH201 Beam Patterns ............................................................................................................................................................................................ 11

6.5

LAYOUT RECOMMENDATIONS.......................................................................................................................................................... 12

Recommended PCB Footprint................................................................................................................................................................................ 12

6.6

PCB REFLOW RECOMMENDATIONS: ................................................................................................................................................. 13

Use of Level Shifters ............................................................................................................................................................................................... 13

6.7
7

Ordering Information............................................................................................................................................................... 15
7.1
7.2
7.3
7.4

8

TYPICAL OPERATING CIRCUITS ......................................................................................................................................................... 13

PART NUMBER DESIGNATION .......................................................................................................................................................... 15
PACKAGE MARKING....................................................................................................................................................................... 15
TAPE & REEL SPECIFICATION ........................................................................................................................................................... 16
SHIPPING LABEL ............................................................................................................................................................................ 16

Revision History ....................................................................................................................................................................... 17

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CH201
1 SIMPLIFIED BLOCK DIAGRAM

Figure 1. Simplified Block Diagram

1.1 ABSOLUTE MAXIMUM RATINGS
MAX.

UNIT

AVDD to VSSPARAMETER

MIN.
-0.3

TYP.

2.2

V

VDD to VSS

-0.3

2.2

V

SDA, SCL, PROG, RST_N to VSS

-0.3

2.2

V

Human Body Model (HBM)(1)

-2

2

kV

Charge Device Model (CDM)(2)

-500

500

V

Latchup

-100

100

mA

Temperature, Operating

-40

85

°C

90

%RH

20

mA

260

°C

Electrostatic Discharge (ESD)

Relative Humidity, Storage
Continuous Input Current (Any Pin)

-20

Soldering Temperature (reflow)

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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CH201
2 PACKAGE INFORMATION
2.1 8-PIN LGADESCRIPTION
CH101 and CH201 Ultrasonic Transceiver Handling andAssembly Guidelines

DOCUMENT NUMBER
AN-000159

2.2 PIN CONFIGURATION

Figure 2. CH201 Package Top View

2.3 PIN DESCRIPTION
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 1. Pin Descriptions

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CH201
2.4 PACKAGE DIMENSIONS

Figure 3.Package dimensions

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CH201
3 ELECTRICAL CHARACTERISTICS
AVDD = VDD = 1.8VDC, VSS =0V, TA = +25°C, MIN/MAX AREFROM TA = -40°C TO +85°C,
UNLESS OTHERWISE
SPECIFIED. PARAMETERSYMBOL

CONDITIONS

MIN

TYP

MAX

1.62
1.62

1.8
1.8

1.98
1.98

UNITS

POWER SUPPLY
Analog Power Supply
Digital Power Supply

AVDD
VDD

V
V

ULTRASONIC TRANSMIT CHANNEL
Operating Frequency

Maximum Range
Minimum Range
Measuring Rate (Sample/sec)
Field of View
Current Consumption (AVDD +VDD)Measurement Time
Programming Time85
TxRx OPERATION (GPR FIRMWARE LOADED)
Wall Target
5(1)Max Range
58mm Diameter Post
2.7(1)Min Range
0.2(2)
5m
25
SR
1m
100
Configurable up to 180º
FoV
IS

SR=1S/s, Range=1m
SR=1S/s, Range=5m
SR=25S/s, Range=1m
SR=25S/s, Range=5m
5m max range

8
14
63
247
36
60

kHz

m
m
m
Sample/s
Sample/s
deg
μA
μA
μA
μA
ms
ms

Table 2.
Notes:
1.
2.

Measurement tested using 45° FoV acoustic housing.
Tested with a stationary target. While objects closer than 20 cm can be detected, the range measurement is not ensured.

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CH201
3.1 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

SYMBOLVOL
VOH
VIL_I2C
VIH_I2CIL

fSCL

CONDITIONSMINTYPDIGITAL I/O CHARACTERISTICS
SDA, INT, ISINK=XmA
INT
0.9*VVDD
SDA, SCL
SDA, SCL
0.7*VVDD
SDA,SCL, INT(Inactive),
TA=25°C
DIGITAL/I2C TIMING CHARACTERISTICS
I2C Fast Mode
Table 3. Electrical Characteristics Cont’dPage 7 of 18
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400

MAX
0.4
0.3*VVDD
±1

UNITS
V
V
V
V
μA

kHz

CH201
4 TYPICAL OPERATING CHARACTERISTICS
AVDD = VDD = 1.8VDC, VSS = 0V, TA = +25°C, unless otherwise specified.

Figure 4. Typical Beam Pattern – MOD-CH201-00-01 45 deg FoV module(Measured with a 1 m2 flat plate target at a 1m range)

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CH2015 DETAILED DESCRIPTION
5.1 THEORY OF OPERATIONThe CH201 is an autonomous, digital output ultrasonic rangefinder. The Simplified Block Diagram in Figure 1 shows the main
components at the package-level. The package includes 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.

5.2 DEVICE CONFIGURATIONA CH201 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 CH201. It also supports hardware-triggering of theCH201 for applications requiring multiple transceivers. Program files can also be tailored to the customer’s application. Contact
Chirp for more information.
CH201 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 CH201 during normal operation, allowing the host processor to be shut down into its lowest power mode until the CH201
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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CH201
6 APPLICATIONS
6.1 CHIRP CH201 DRIVER
Chirp provides a compiler- and microcontroller-independent C driver for the CH201 which greatly simplifies integration. The CH201
driver implements high-level control of one or more CH201s attached to one or more I 2C ports on the host processor. The CH201
driver allows the user to program, configure, trigger, and readout data from the CH201 through use of C function calls without directinteraction with the CH201 I2C registers. The CH201 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 CH201
driver.

6.2 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 CH201’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 3-4m away from the CH201 sensor.
For additional information, please refer to AN-000214 Presence Detection Application Note and associated Presence Detection S/W.

6.3 INTERFACING TO THE CH201 ULTRASONIC SENSOR
The CH201 communicates with a host processor over the 2-wire I2C protocol. The CH201 operates as an I2C slave and responds tocommands issued by the I2C master.
The CH201 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 CH201. 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 CH201 uses clock stretching to allow for enough time to respond to the I 2C master. The CH201 clock stretches before theacknowledge (ACK) bit on both transmit and receive. For example, when the CH201 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 CH201 is receiving, it holds the SCL line low after it
receives the 8th bit in a byte. The CH201 then chooses whether to ACK or NACK depending on the received data and releases the SCL
line.
Figure 5 shows an overview of the I2C slave interface. In the diagram, ‘S’ indicates I2C start, ‘R/W’ is the read/write bit, ‘Sr’ is arepeated start, ‘A’ is acknowledge, ‘P’ is the stop condition. Gray boxes indicate the I2C master actions; white boxes indicate the I2C
slave actions.

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CH201Figure 5. CH201 I2C Slave Interface Diagram

6.4 DEVICE MODES OF OPERATION
Free-Running ModeIn the free-running measurement mode, the CH201 runs autonomously at a user specified sample rate. In this mode, the INT pin is
configured as an output. The CH201 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 CH201 over the I2C interface.

Hardware-Triggered ModeIn the hardware triggered mode, the INT pin is used bi-directionally. The CH201 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 CH201 transceivers. The host controller can use the individual INT pins of several transceivers tocoordinate the exact timing.

CH201 Beam Patterns
The acoustic Field of View is easily customizable for the CH201 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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CH201
6.5 LAYOUT RECOMMENDATIONS
Recommended PCB Footprint

Dimensions in mm

Figure 6. Recommended PCB Footprint

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CH201
6.6 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 in Figure 7 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

6.7 TYPICAL OPERATING CIRCUITS

3 SDA
2 SCL
CH-201 8 RESET_N
1.8V VDD
1 INT
6
PROG
0.1µF
5
4
AVDD

VDD
Microcontroller
SDA (Master)
SCL (Master)
GPIO
GPIO
GPIO

7

GND

VSS

Figure 8. Single Transceiver Operation

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10k

2k2

2k2

1.8V

CH201

3 SDA
2 SCL
CH-201 8 RESET_N
1.8V VDD
1 INT
6
PROG
0.1µF
5
4
AVDD

10k

2k2

2k2

1.8V
VDD
Microcontroller
SDA (Master)
SCL (Master)
GPIO
GPIO
GPIO
GPIO
GPIO
GPIO
GPIO

7

VSS

GND

3 SDA
2 SCL
CH-201 8 RESET_N
1.8V VDD
1 INT
6
PROG
0.1µF
5
4
AVDD

7

VSS

3 SDA
2 SCL
CH-201 8 RESET_N
1.8V VDD
1 INT
6
PROG
0.1µF
5
4
AVDD

7

VSS

Figure 9. Multi-Transceiver Operation

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CH201
7 ORDERING INFORMATION
7.1 PART NUMBER DESIGNATION

CH201-xxABx
Product Family
CH201 = Long-Range Ultrasonic ToF Sensor

Shipping Carrier

Product Variant
00AB = Product Variant

R = Tape & Reel
Figure 10. Part Number Designation

This datasheet specifies the following part numbers
PART NUMBER
CH201-00ABR

PACKAGE BODY
3.5 mm x 3.5 mm x 1.26 mm LGA-8L

QUANTITY
1,000

Table 4. CH201 Part Number

7.2 PACKAGE MARKING

Figure 11. Packaging Marking

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PACKAGING
7” Tape and Reel

CH201
7.3 TAPE & REEL SPECIFICATION

Dimensions in mm

Figure 12. Tape & Reel Specifications

7.4 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

Figure 13. Shipping Label

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CH201
8 REVISION HISTORYDATEREVISION

CHANGES

06/02/2020

1.0

Initial Release

9/22/2020

1.1

Fixed minor typos

1/7/2021

1.2

Updated Package Dimensions with tolerances

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Document Number: DS-000379
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CH201This 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 registeredtrademarks are the property of their respective companies. Chirp Microsystems sensors should not be used or sold in the development, storage, production or utilizationof 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 atrademark of TDK Corporation. Other company and product names may be trademarks of the respective companies with which they are associated.

©2020 Chirp Microsystems. All rights reserved.

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