Fairchild Fan8902 (KA3902) Data Handbook

Summary

This monolithic integrated circuit is a specialized DC Fan Motor Controller, optimized for low supply current in demanding automotive systems. It provides robust speed regulation via built-in PWM current control and includes critical protective features such as Over Voltage Protection (OVP), Over Current Protection (OCP), Thermal Shutdown (TSD), and Under Voltage Lockout (UVLO). The comprehensive manual details circuit functionality, pin assignments, electrical characteristics, and application guides for engineers designing reliable cooling solutions.

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查询FAN8902供应商

www.fairchildsemi.com

FAN8902(KA3902) DC FAN Motor Controller

Features Description Built-in PWM Current Control Circuit The FAN8902 is a monolithic integrated circuit, designed Built-in 5V Regulator for the PWM control of a DC fan motor current in an Low Supply Current automotive systems. It allows the fan motor speed to be Stalled Motor Current Limitation controlled linearly and efficiently. Built-in Over Voltage Protection (OVP)

Built-in Over Current Protection (OCP) 14-DIP-300

Built-in Load Dump Protection Built-in Thermal Shutdown (TSD) Circuit Built-in Under Voltage Lockout (UVLO) Circuit

Typical Application Ordering Information DC for Motor Control for Automotive

Device Package Operating Temperature FAN8902 14-DIP-300 -40°C ~ +90°C

Rev. 1.0.3

Page Summary Contents For Fairchild Fan8902 (KA3902) Data Handbook

Page 1 查询FAN8902供应商 www.fairchildsemi.com FAN8902(KA3902) DC FAN Motor Controller Features Description Built-in PWM Current Control Circuit The FAN8902 is a monolithic integrated circuit, designed Built-in 5...

Page 2 FAN8902(KA3902) Pin Assignments 14CMD La CMDa VCC CMDb OUT SG F A N 8 9 0 2 PG RT / CT CS VREF CL CH NC Pin Definitions Pin Number Pin Name Pin Function Description CMD Motor Current Command Input CMD...

Page 3 FAN8902(KA3902) Internal Block Diagram Vref Vref UVLO VCC 4R LOGIC PWM Comparator × 5 CS Oscillator RT/CT CMDb SGND

Page 4 FAN8902(KA3902) Absolute Maximum Ratings Parameter Symbol Value Unit Supply Voltage VCC CMD Input Voltage VCMD Peak Output Current IOPK ±0.8 Power Dissipation PD Operating Voltage Parameter Symbol Min...

Page 5 FAN8902(KA3902) Electrical Characteristics (Unless otherwise, Ta=25°C, VCC=5V, VM=12V) Parameter Symbol Conditions Min. Typ. Max. Unit REFERENCE Reference Voltage Vref Iref=1m A 4.75 5.0 5.25 Line Reg...

Page 6 FAN8902(KA3902) Application Information 1. Under Voltage Lockout (UVLO) Vref & output driver TH(ST) 8.0V THYS 1.2V FAN8902 6.8V 8V VTH(ST) 2. Current Sensing Circuit PWM comparator Imax=1V PWM Log...

Page 7 FAN8902(KA3902) 4. Oscillator Component Selection VCT [V] VH=3.0 Logic+ VL=1.75 VHVLID TC=39.0Td=1.0 The oscillator timing components can be calculated as follows: TC RT CT× In Vref VL–( Vref VH–( )⁄[...

Page 8 FAN8902(KA3902) 6. Slope Compensation An unconditional instability of the inner current loop exists for any fixed frequency current-mode converter operating above 50% duty cycle. Therefore, to guarant...

Page 9 FAN8902(KA3902) In the steady state, the terminal voltage on a motor is consisted of a back EMF and the voltage drop on the armarture resistors. When the motor happens to be stalled, the back EMF beco...

Page 10 FAN8902(KA3902) Reduced switch-on time Motor current Uncontrolled without the FAN8902 Controlled with the FAN8902 Normal operation Stalled state 8. Operational Mode Selection The FAN8902 has three ope...

Page 11 FAN8902(KA3902) Test Circuit Iout TP 4 IN 4IN 5IN 6 Cid 1µF CO 47µF La VCC OUT PG CS CL NC CMD CMDa CMDb SG RT / CT VREF CH 10k CT 1n F C2 IN 1 TP 1 IN 2 TP 2 TP 3 IN 3

Page 12 FAN8902(KA3902) Typical Application CMD La Current command NC CMDa VCC NC CMDb OUT SG PG R11 F A N 8 9 0 2 RT / CT CS VREF CL CH NC NC

Page 13 FAN8902(KA3902)

Page 14 FAN8902(KA3902) DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUM...

Manual Details

Brand	Fairchild
Pages	14
File Size	132.53 KB
Published	July 15, 2026

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Frequently Asked Questions

What is the maximum current the FAN8902 output driver can handle?

It has a peak output current (IOPK) of ±0.8 A.

Does this chip have built-in protections against electrical failures?

Yes, it includes Over Voltage Protection (OVP), Over Current Protection (OCP), Load Dump Protection, Thermal Shutdown (TSD), and Under Voltage Lockout (UVLO).

What temperatures can the FAN8902 operate within?

The operating temperature range is -40°C to +90°C.

How does the chip regulate fan speed?

It contains a built-in 5V regulator for PWM control of the DC fan motor current, allowing linear and efficient speed control.