Datasheet

UNISONIC TECHNOLOGIES CO., LTD
UH255
CMOS IC
SMART MOTOR DRIVER WITH
INTEGRATED HALL SENSOR

DESCRIPTION
The UH255 is a single coil motor driver with integrated Hall
sensor.Lock-shutdown and auto-restart function protects the motor
from being over-heated and restarts the motor after being locked.
The rotation speed function is also integrated in the UH255, the
system could detect the rotation speed of motor when using
UH255 by the ‘FG’ pin.
The UH255 also uses Soft-switch phase-switching technique to
reduce the vibration and acoustic noise.
PWM is used for the speed control for UH255.Two types of
PWM input signals could be used: voltage mode PWM & pulse
mode PWM.

6
5
4
1
2
3
SOT-26
FEATURES
* Soft switching output driver.
* Built-in Hall sensor motor driver.
* Motor lock protection and automatic restart.
* Thermal shutdown protection.
* PWM speed control.

ORDERING INFORMATION
Ordering Number
UH255G-AG6-R

Package
SOT-26
Packing
Tape Reel
MARKING
www.unisonic.com.tw
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UH255
CMOS IC

PIN CONFIGURATIONS

PIN DESCRIPTIONS
PIN NAME
PIN TYPE
PIN DESCRIPTION
FG
O
Frequency generation
VSS
G
Ground
NO
O
Driver output
SO
O
Driver output
VDD
P
Power supply
PWM
I
Pulse width modulation speed control
Note: I=Input, O=Output, I/O=Input/Output, P=Power Supply, G=Ground.

BLOCK DIAGRAM
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
CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
DC Supply Voltage(VDD,FG)
VDD
6.5
V
Supply Current
IDD
3
mA
Continous Current
ICONT
500
mA
Hold Current
IHOLD
800
mA
PG,RD sink current
ISINK
25
mA
Magnetic Flux Density
B
Unlimited
Gauss
Allowable power dissipation
PD
520
mW
Junction Temperature
TJ
170
°C
Operating Temperature
TOPR
-20 ~ +105
°C
Storage Temperature
TSTG
-40 ~ +150
°C
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.

RECOMMENDED OPERATING COMDITIONS
PARAMETER
Input Voltage
Operating Temperature

SYMBOL
VDD
TA
MAX
5.5
90
UNIT
V
°C
SYMBOL
θJA
RATINGS
278
UNIT
°C/W
ELECTRICAL CHARACTERISTICS (TA =25°C, unless otherwise specified)
PARAMETER
Average Supply Current(No load)
Output Saturation Voltage (FG)
Output leakage current (FG)
On resistance (Rpmos+Rnmos)
Thermal Shutdown Threshold

TYP
THERMAL DATA
PARAMETER
Junction to Ambient

MIN
1.8
-10
SYMBOL
TEST CONDITIONS
IDD
VSAT
IOUT= 10mA
ILEAK
VOUT=5V
RON
TSD
MIN
TYP
1.8
MAX
0.5
1
0.8
165
UNIT
mA
V
uA
Ω
°C
MAGNETIC CHARACTERISTICS
PARAMETR
Operate Point
Release Point
Hysteresis
SYMBOL
BOP
BRP
BHYS
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MIN
TYP
25
-25
50
MAX
UNIT
G
G
G
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HYSTERESIS CHARACTERISTICS

TYPICAL APPLICATIONS CIRCUIT
Notes: 1.Capacitor C1 is necessary to use for the decoupling between VDD and VSS and should be placed as close to
the IC as possible.
2. The PWM pin contains an internal pull-up resistor so the UH255 will rotate at full-speed(100% ON) when
this pin is floating.
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UH255

CMOS IC
OUTPUT WAVEFORMS DESCRIPTION
VDD
Restart Time
Shutdown Time
Ton
Toff
NO&SO
The voltage level depends on ‘SO’pin’s
level before ‘Lock-shutdown’
FG
Notes: 1. FG is open drain,the high level of signal depends on the external supply voltage.
2. The on torque time of motor is equal to the restart time.
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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×VDD to 0.5×VDD, 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×VDD) and 100%(DC voltage is
higher than 0.5×VDD).
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×VDD and the
‘Low’ value should be lower than 0.14×VDD.
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.
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