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WSH41S
Hall Effect Sensor IC with Thermal Lock Protection ,Auto Restart and Speed Control Function
Features: Operate from 2.8V to 20V supply voltage. On-chip Hall sensor. Internal bandgap regulator allows temperature compensated operations and a wide operating voltage range. High output sinking capability up to 600mA for driving large load. Lower current change rate reduces the peak output voltages during switching. Available in rugged low profile SOT-25 packages. PS pin can accept PWM signal to program rotation speed. Built-in protection diode for reverse power supply fault. Built-in thermal lock protection and auto-restart function. General Description: WSH41S is designed to integrate Hall sensor with complementary output drivers and speed control function together on one chip, it is suitable for speed measurement, revolution counting, positioning, and DC brushless motors. It includes a temperature compensated voltage regulator, a differential amplifier, a Hysteresis controller, two open-collector output drivers capable of sinking 600mA current load and PS pin which can accept PWM signal to do speed control programming. An on-chip protection diode is implemented to prevent reverse power fault. And built-in thermal lock protection and auto-restart function is suitable for super high speed fan. It can replace the function of lock protection and auto restart function. The power will be shutdown automatically at 130C to prevent the coils be damaged and atuo-restart after cooling down. The temperature-dependent bias increases the supply voltage of the hall plates and adjusts the switching points to the decreasing induction of magnets at higher temperatures. Subsequently, the open collector output switches to the appropriate state. WSH41S are rated for operation over temperature range from -20 C to 100C and voltage ranges from 2.8V to 20V.
Pin Descriptions: SOT-25
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 1
WSH41S
Name VDD Vss PS OUT2 OUT1 P/I/O P P I O O Pin# 1 2 3 4 5 Description Positive Power Supply Ground Power Sleep Output Pin 2 Output Pin 1
Absolute Maximum Rating (at Ta=25 C) Supply Voltage Vcc -------------------------Output / FG breakdown Voltage Vout/Vfg --------------------Magnetic flux density B -------------------------Reverse Protection Voltage Vr -------------------------Output Current continuous Ic -------------------------Hold current Peak current FG ON Current (continuous) Operating Temperature Range Storage Temperature Range Package Power Dissipation Ih Ip If
20V 25V Unlimited 20V 500mA
-----------------------600mA ------------------------800mA -------------------------- 20mA (-20C to +100C) (-65C to +150C) 350mw for SOT-25
Ta -------------------------Ts -------------------------Pd --------------------------
Electrical Characteristics: (T=+25C, Vcc=2.8V to 20V) Characteristic Symbol Test Conditions Min Typ Max Units Supply Voltage Vcc V 2.8 20 Output Saturation Vout(sat) Vcc=20V, Ic=200mA V 0.15 0.4 Voltage B > Bop Sleep Current Isleep Vcc=20V, PS<0.6V mA 2 6 Output Leakage Ileakage Vcc=20V, B < Brp uA <0.1 10 Current Supply Current Isupply Vcc=20V, Output & mA 15 23 FG Open Output Rising Time Tr 3.0 us Vcc=12V, RL=820 10 CL=20Pf Output Falling Tf us Vcc=12V, RL=820 0.3 1.5 Time CL=20Pf Output Time us t Vcc=12V, RL=820 0.3 3 Differential CL=20Pf
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 2
WSH41S
Function Block:
Magnetic Characteristics: Characteristics Operate Point Release Point Hysteresis Window Symbol Bop Brp Bop-Brp Quantity Grade A Grade B Grade A Grade B -50 -70 Min Ta= -20C to +100C Typ. Max 25 50 30 70 -25 -30 40 Unit Gauss Gauss 200 Gauss
Ordering Information: SOT- 25: WSH41S-XPD Elec. Grade 1: A Grade (50 Gauss) 2: B Grade (70 Gauss)
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 3
WSH41S
Test Circuit:
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 4
WSH41S
Package Information: SOT-25
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 5
WSH41S
Application Circuit:
Figure 1. WSH41S with power sleep function is designed for reducing power consumption and noise for smart cooling in various applications especially for portable computer systems while system processors are not in full loading. 1. Green PC System: PC and Notebook systems switch to sleep mode and start screen savor when CPU is in idle state. Mean while, system can apply an active low signal VPS to enable WSH41S power sleep function which makes DC fans of CPU cooler and even VGA card stop running until CPU loading is heavy again in order to reduce unnecessary power consumption. 2. CPU with Temperature Sensor Feature: System can detect CPU junction temperature that reflects the CPU operating status. If CPU is not in heavy loading, junction temperature is not high enough to affect CPU operation, there is no need to start DC fan to consume extra power. System designer can simply program the system based on two CPU temperatures to apply a proper input signal to enable or disable WSH41S power sleep function. For example, when CPU junction temperature drops to point A (CPU is in idle state or lightly loading), system enables WSH41S power sleep function. At this point, DC fan stops running and consumes power as low as 2mA typically. If CPU junction temperature increases to
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 6
WSH41S
point B, system disables WSH41S power sleep function and DC fan starts running again to cool down CPU temperature. Most of the time, system processors are in idle state for most users. DC fans with power sleep function can save up to 98% of power when CPU is idle or even lightly loading. Temperature-Dependent Hysteresis Window
3. Smart Cooling by Thermistor: An alternative way to achieve thermal-controlled power sleep function is the use of a thermistor that is sensitive to the operating ambient temperature. The thermistor can be placed at the hottest spot of the system with very simple voltage divider circuit as shown below. System designer can select a proper thermistor to adjust Vps level (Vps switching level is approximate 1.8V) to enable/disable power sleep function based on the Temperature-Dependent Hysteresis Window shown above. In this application, the thermistor has a characteristic of negative temperature-dependent coefficient.
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 7
WSH41S
4. Speed Control: DC fan Speed Control can be programmed by applying a PWM signal to PS pin of WSH41S. For example, if PWM signal is programmed with pulse width of H/L ratio of 1/1 in a duty cycle, DC Fan consumes only 50% of power and revolution speed is approximately 50% of full speed. If PWM signal is programmed with pulse width of H/L ratio of 3/2 in a duty cycle, DC Fan consumes only 60% of power and revolution speed is approximately 60% of full speed and so on and so forth.
It is recommended to apply a "H"(>1.8V) or a "L"(<0.6V) signal to the PS input pin to activate the power sleep circuit. Sleep Mode: VPS = "L" (<0.6V) Normal Operation: VPS = "H" (>1.8V)
Winson reserves the right to make changes to improve reliability or manufacturability. (c)Winson, 2004/3/3 8

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