ISZ-650 Single-Axis Z-Gyroscope

Product Specification

PS-ISZ-0650B-00-02

Release Date: 07/08/09

CONFIDENTIAL & PROPRIETARY

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Figure 5

8.2.6

External Low-Pass Circuitry

To further attenuate high-frequency noise, an optional external low-pass filter may be used.

8.2.7

Gyro Outputs

The ISZ-650 gyro has two Z-outputs, with scale factors and full-scale sensitivities as summarized

below.

Axis

Gyro Output

Sensitivity (mV/º/s)

Full-Scale Range (±º/s)

Z

Z-OUT

0.5

2000

Z4.5OUT

2.27

440

Having two sensitivities and two full-scale ranges for one axis allows the end user to have one output

that can be used for faster motions such as full-motion gaming (over a full scale range of ±2000º/sec),

and a second output that can be used for slower motions such as for gesture and menu-navigation

functionality (over a full scale range of ±440º/sec). Thus a lower-resolution analog-to-digital converter

(ADC) may be used to digitize the motion, with the gain of 4.5 in the Z4.5OUT output effectively giving

the user additional two-plus bits of resolution.

The ISZ-650 gyro outputs are independent of supply voltage (i.e. they are not ratiometric).

Gyro rotation rate is calculated as:

(Gyro Output Voltage – Gyro Zero-Rate Out) / Sensitivity

where the Zero-Rate Output (ZRO) is nominally VREF. There is a temperature dependence to ZRO,

and an initial accuracy to ZRO.

8.2.8

Auto Zero

Auto Zero (AZ) is a function that is used to maximize the gyro’s dynamic range when using the

Z4.5OUT output.

AZ works by keeping the gyro’s Zero-Rate Output (ZRO) close to VREF, and thus allows the user to

achieve a wider usable signal range, without using an external analog high pass filter.

-30

-25

-20

-15

-10

-5

0

5

10

1

10

100

1000

Frequency (Hz)

-30

-25

-20

-15

-10

-5

0

5

10

Phase

Gain

Nominal

Limits

LPF Phase & Gain