UH255G-AG6-R Datasheet, PDF (6/6 Pages) Unisonic Technologies – CMOS IC

UH255
CMOS IC
 FUNCTIONAL DESCRIPTIONS
Refer to the block diagram above, UH255 is composed of the following blocks:
1.Bias generator
The bias generator provides bias references for the analog blocks.
2.Oscillator
The integrated oscillator provides the clock signal for the digital control logics.
3.Power-on Reset
The block of power-on reset is used to detect the power-up ramp and reset the digital circuits.
4.Chopper Amplifier
The chopper amplifier structure can achieve a higher magnetic sensitivity and dynamically removes both the offset
and flicker noise at the same time.
5.Digital control logics
Generates controlling signals for the Hall sensor and Coil driver and a tachometer signal output(FG).
6.PWM speed control
Voltage mode PWM:
Applying a DC voltage to the PWM pin and the UH255 will generate PWM pulses internally. The rotation speed will
be higher if the voltage applied to the PWM pin is higher. The relation of the applying DC voltage and the ‘ON’ duty
cycle of PWM pulse is as follows:
When the applying DC voltage is from 0.14×V_DD to 0.5×V_DD, the ‘ON’ duty cycle of PWM pulse is linear with the
DC voltage. Otherwise the ‘ON’ duty cycle is zero(DC voltage is lower than 0.14×V_DD) and 100%(DC voltage is
higher than 0.5×V_DD).
Pulse mode PWM:
User can also apply PWM pulses directly to the PWM pin. The UH255 will pass this pulse to the coil driver with the
original duty-cycle ratio.
Notes: 1.While using pulse mode PWM, the ‘High’ value of the input pulse should be higher than 0.5×V_DD and the
‘Low’ value should be lower than 0.14×V_DD.
2. The PWM pulse frequency should be higher than 200Hz, and the recommended frequency range is higher than
30KHz where there PWM input pulses will not generate acoustic noise.
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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