How to choose a Time-of-Flight sensor

[LauraCx]

Summary

Choosing the right VL53 Time-of-Flight (ToF) sensor depends on several factors related to the specific application requirements.

This article presents some comparisons between ST ToF sensors.

The offerings from ST can be broken down into two classes. There are the single-zone sensors with circular fields of view from 18^o to 27^o and the multizone sensors that have rectangular fields-of-view of either 45^o x 45^o or 60^o x 60^o.

1. Single-zone sensors

Here are the key considerations for single-zone sensors to help you decide.

The single-zone sensors to be considered are: VL53L0X, VL53L1X, VL53L1CB, VL53L3CX, VL53L4CD, VL53L4CX, VL53L4ED

1.1 Range requirements

• VL53L0X: Suitable for short-range applications (up to 2 meters).
• VL53L1X: Offers a longer range - up to 4 meters. Includes a lens to gather more photons.
• VL53L1CB: Same hardware as the VL53L1CX but includes fancier software. Up to 8 meters.
• VL53L3CX: Provides a multi-target detection capability with a range up to 6 meters.
• VL53L4CD: Designed for short-range applications with high-speed ranging (up to 1.3 meters). Better linearity down to 5 mm.
• VL53L4ED: Same as VL53L4CD, but with an extended temperature range of up to 105°C.
• VL53L4CX: Better software allows ranging up to 6 m. Short distance linearity down to 10 mm.

2.2 Field of View (FoV)

• VL53L0X, VL53L3CX: 25^o FoV
• VL53L1X, VL53L1CB: 27^o FoV
• VL53L4CD, VL53L4CX, and VL53L4ED: 18^o FoV

2.3 Power consumption

• All the single-zone sensors use about 18 mA while they are ranging.

2.4 Integration and interface

• I²C interface: All VL53 sensors use the I²C interface.
• Size and package: All the single-zone sensors are footprint compatible and are interchangeable. The VL53L1CX and the VL53L1CB and a touch wider and longer, but still fit the same pads.

2.5 Environmental conditions

• VL53L1CB: Better performance in varying lighting conditions.
• VL53L4CX: Absolutely our easiest to integrate and best value.

2.6 Cost

• Budget constraints may also influence ones decision. All these sensors are priced fairly close together. The VL53L4CD is the least expensive, and the VL53L1 sensor costs a bit more due to the additional lens.

2.7 Example use cases

• VL53L0X, VL53L4CD: Ideal for simple distance measurement in robotics or proximity sensing in consumer electronics.
• VL53L1X: Suitable for drones, robotics, and industrial applications where longer range and higher accuracy are needed.
• VL53L1CB, VL53L3CX, VL53L4CX: Useful in applications requiring detection of multiple objects, such as smart home devices.

2.8 Single-zone sensors summary table

Sensor	Range	FoV	Accuracy	Special features
VL53L0X	Up to 2 m	25o	Basic	Cost-effective, general-purpose
VL53L1X	Up to 4 m	Adjustable to 27o	Basic	Longer range, better accuracy
VL53L1CB (or VL53L1)	Up to 8 m	Adjustable to 27o	Good	Multi-target detection
VL53L3CX	Up to 3 m	25o	Good	Multi-target detection
VL53L4CD	Up to 1.3 m	18o	Basic	High-speed, short-range
VL53L4CX	Up to 6 m	18o	Good	Multi-target detection
VL53L4ED	Up to 1.3 m	18°	Basic	High temperature

By considering these factors, one can select the most appropriate VL53 Time-of-Flight sensor for the specific application needs.

3. Multizone sensors

If the application requires a wider Field-of-View, there are two options. One is to use more sensors. Or one can use a multizone sensor. Multizone sensors double or triple the FoV in both directions, and they return the distances in many zones. One can get 16 distances (in a grid of 4x4) or 64 distances in a grid of 8x8 zones

Multizone sensors measure distances in multiple zones simultaneously making them suitable for applications like gesture recognition, object detection, and environmental mapping. Here are the key considerations to help you decide:

The multiple zone sensors to be considered are: VL53L7CX, VL53L7CH, VL53L8CX, VL53L8CH

3.1 Number of zones

• VL53L7CX: Provides up to 64 zones (8x8 grid) with a very wide FoV.
• VL53L8CX: Offers up to 64 zones (8x8 grid), providing detailed spatial resolution.
• VL53L7CH/VL53L8CH: Offer the same as the CX variants, but also return the actual photon return signature, which can be used in AI applications and heavy science. 
  Additionally, CH versions have compact normalized histogram (CNH) which gives the system access to original sensor power to enable AI. CNH resolution and dataset contains much more information than ranging distances.  

3.2 Range requirements

• VL53L8CX: Suitable for medium-range applications (up to 4 meters).
• VL53L7CX: Offers a wider FoV (up to 3.5 meters).

3.3 Field of View (FoV)

• VL53L8CX: Wide FoV, 45^o X 45^o suitable for applications needing broad area coverage.
• VL53L7CX: Extrawide FoV 60^o X 60^o. Designed to match some camera modules.

3.4 Accuracy and precision

• VL53L8CX: With a more powerful VCSEL (laser) than the VL53L7, provides better accuracy and precision for medium-range applications.
• VL53L7CX: Offers good accuracy and precision.

3.5 Power consumption

• The VL53L8CX can use up to 60 mA while ranging but needs much less time to integrate, making it very similar to a single-zone sensor in power consumption.
• The VL53L7CX spreads the light in an area almost 2X the spread of the L8, requiring power for more time. And due to this spread, the sensor ranges a bit less distance.

3.6 Integration and interface

• I²C interface: Both sensors use the I²C interface, but the VL53L8CX also has an SPI interface.

3.7 Environmental conditions

• VL53L8CX: Designed to handle more challenging environmental conditions and provides better performance in detecting objects at longer distances. It really is the best ST ToF sensor.
• VL53L7CX: Performs well in varying lighting conditions and can handle multiple objects within its FoV.

3.8 Cost

• Multizone sensors are more expensive than the single-zone ones. But they cover the same area as 4 single-zone sensors and are only about twice as expensive

3.9 Example use cases

• VL53L8CX: Ideal for applications like gesture recognition, smart home devices, and medium-range object detection.
• VL53L7CX: The same applications as the VL53L8CX, but with a wider field of view and a bit more power consumption overall.
• VL53L7CH/VL53L8CH: Robotic applications, system activation, content management, keystone correction

3.10 Multizone sensor summary table

Sensor	Range	Zones	FoV	Accuracy	Special features	Comm I/F	Applications
VL53L8CX VL53L8CH	Up to 4m	64 (8x8)	45ox45o	High	Long-range, broad area coverage	I²C, SPI	· Gesture recognition · Liquid level monitoring · Laser assisted autofocus (LAF) · Smart cup detection (L8CH)
VL53L7CX VL53L7CH	Up to 3.5m	64 (8x8)	60ox60o	High	Long-range, enhanced performance	I²C	· Robots · Reality/virtual reality (AR/VR) · IoT · Smart cup detection (L7CH)

Sensor	Power consumption	Environmental conditions
VL53L8CX VL53L8CH	Higher power but less time to integrate	· Handling more challenging environmental conditions · Better performance in detecting objects at longer distances.
VL53L7CX VL53L7CH	Lower power but more time to integrate	· Well performance in varying lighting conditions. · Handling multiple objects.

By considering these factors, you can select the most appropriate multizone VL53 Time-of-Flight sensor for your specific application needs.

It should be noted that there’s a VL53L5CX, but the VL53L8CX was designed to replace it for the same cost and power consumption. The VL53L8CX just works better.

Related links

For more information about the products, use the links below:

Single-zone sensor links	Multizone sensor links
VL53L0X	VL53L5CX
VL53L1X	VL53L7CX
VL53L1CB/VL53L1	VL53L7CH
VL53L3CX	VL53L8CX
VL53L4CD	VL53L8CH
VL53L4ED
VL53L4CX

[MFabb.1]

Hi Laura,

Could you kindly update this article by including in the comparison the latest ToFs released?

In particular I would be interested in:

• VL53L5CP
• VL53L7CX
• VL53L8CA

Thank you