Agamem Microelectronics Inc. PRELIMINARY AA51881 SERVO MOTOR CONTROLLER ■ DESCRIPTION The AA51881 is a BJT integrated circuit to be applied on servo motor control applications. The built-in voltage regulator provides the AA51881 with extremely stable output voltage. It also incorporates a linear one-shot and pulse-width demodulator for improved positional accuracy. ■ FEATURES • Built-in voltage regulator. • Larger driving capability. • Internal output NPN power transistor. • Adjustable dead band range control. • Incorporates a protection circuit for "H-Bridge" driving configuration. • Small outline package. ■ APPLICATIONS • Servo motor control. • Radio controlled car, boat, and airplane. • IA products (such as air-condition). • Remote positioning. ■ BLOCK DIAGRAM ©Copyright Agamem Microelectronics Inc. 1 www.agamem.com.tw 2008/5/5 AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. Agamem Microelectronics Inc. PRELIMINARY AA51881 SERVO MOTOR CONTROLLER ■ PIN DESCRIPTION PIN NO. PIN NAME 1 RT 2 EXP1 External PNP Transistor 1 output 3 OUT1 Output Driver 1 5 OUT2 Output Driver 2 6 EXP2 External PNP Transistor 2 output 7 CST Stretcher capacitor 8 NC No Connection 9 VREG 10 VCC Power supply pin 11 RDB Error pulse output 4,12,13 GND Ground pin 14 VIN Input signal 15 POT Servo position voltage 16 CT ©Copyright Agamem Microelectronics Inc. FUNCTION Timing Resistor Regulated Voltage output Timing Capacitor 2 www.agamem.com.tw 2008/5/5 AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. Agamem Microelectronics Inc. PRELIMINARY AA51881 SERVO MOTOR CONTROLLER ■ ABSOLUTE MAXIMUM RATINGS Ta=25℃ SYMBOL PARAMETER VCC PD TSTG Supply voltage RATINGS UNIT 4.8~7 V 300 mW －25~＋125 ℃ Power dissipation Storage temperature range ■ ELECTRICAL CHARACTERISTICS Ta=25℃, Vcc=4.8V SYMBOL PARAMETER ICC Operating current VOL TEST CONDITIONS When output is OFF LIMITS UNIT MIN TYP MAX --5 8 mA When output is ON --- 25 28 mA Output voltage "L" Load resistor 20Ω --- 0.1 0.2 V VOH Output voltage "H" Load resistor 240Ω 3.5 --- --- V IPNP External PNP transistor drive Load resistor 240Ω current 30 --- --- mA VREG Regulator output voltage Load capacitor 0.1uF 2.3 2.45 2.6 V IREG Regulator output current Load resistor 500Ω 4 --- --- mA ■ FUNCTIONAL DESCRIPTION (1) Voltage Regulator This circuit outputs a 2.45-volt temperature compensated reference voltage. This reference voltage is stabilized when the supply voltage is variable. (2) Sawtooth wave & One-Shot Generator Connect a capacitor to CT pin will generate a triangular wave by constant current charging. A typical value is 0.1uF. The constant current is determined by a resistor connected to RT pin. A typical capacitor of approximately 0.1uF should be connected in parallel with the resistor to increase stability. ©Copyright Agamem Microelectronics Inc. 3 www.agamem.com.tw 2008/5/5 AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. Agamem Microelectronics Inc. PRELIMINARY AA51881 SERVO MOTOR CONTROLLER (3) Servo Position & Over-Time logic This circuitry consists of a pulse width comparator, which compares the servo position detection signal (POT pin) from the one-shot timer (CT pin) whose period depends on the resistance of a potentiometer connected to the servo's drive shaft. This feedback is what provides the stability for the control circuitry. (4) Pulse Stretcher The difference between the servo control signal and the feedback signal is the error signal. This error signal is used to toggle the direction the current flows through the servo. The function of this pulse stretcher is to “stretch” the small error signal long enough and increases the duty cycle to the motor for it can maintain sufficient holding force. The circuit also implements a “dead band” function that prevents servo jitter and hunting. This is a range over which differences between the input and reference signals will not cause servo operation. When the signal differences exceed this “dead band” range, drive to the motor occurs. Servo’s drive shaft. The dead band will change according to the value of resistor connected to the RDB pin. (5) Directional Logic Control The comparator circuit compares pulses from the servo control input (VIN pin) and the voltage controlled pulse generator and provides either a positive or a negative output depending on whether the signal pulse width is larger or smaller than the position generator’s output pulse (POT pin). Application of this error voltage to the motor driver circuit causes the motor to turn in a direction that will minimize the error until both pulse widths are the same. (6) PWM Control This signal generated by directional logic control block is used to control a flip-flop that toggles the direction the current flows through the motor. The outputs of the flip-flop drive an H-Bridge output driver block that handles the high current going through the motor. This blocks output will be turned on or off with each input pulse based on the status of the directional logic. The PWM drive techniques provide the benefits of reduced power dissipation, improved servo motor performance and positively affect system efficiency. (7) Output driver The output driver controls the servo current direction. For light load application, the servo can be connected with OUT1 and OUT2 pin only. For heavy load application, the EXP1 and EXP2 pin will be connected to the base of the external PNP transistor. It drives in an H-bridge configuration (The sink NPN drivers are built inside the chip). ©Copyright Agamem Microelectronics Inc. 4 www.agamem.com.tw 2008/5/5 AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. AA51881 Agamem Microelectronics Inc. PRELIMINARY SERVO MOTOR CONTROLLER ■ TYPICAL APPLICATION EXAMPLE A. Half H-Bridge application using two external PNPs VS VS Q2 A695 10 EXP1 VCC 2 OUT1 3 VIN 14 OUT2 EXP2 M 5 R2 20KΩ CT POT 1 16 15 7 4 R3 1KΩ C3 0.1uF C1 0.1uF C2 0.1uF R7 1KΩ RDB CST GND GND GND 11 12 VR1 5KΩ 6 VREG 9 RT Q1 A695 C8 103pF R1 470KΩ 13 R4 150KΩ C4 0.22uF C5 4.7uF B. Full H-Bridge application using two PNPs and two NPNs ©Copyright Agamem Microelectronics Inc. 5 www.agamem.com.tw 2008/5/5 AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. Agamem Microelectronics Inc. PRELIMINARY AA51881 SERVO MOTOR CONTROLLER C. Full H-Bridge application using two PMOSs and two NMOSs ■ ORDERING INFORMATION ORDER NO. PACKAGE PACKING Q’TY AA51881C SSOP 16L TAPE & REEL 2,500ea ©Copyright Agamem Microelectronics Inc. 6 MARK CHART AA51881 XXXX C www.agamem.com.tw 2008/5/5 AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. Agamem Microelectronics Inc. PRELIMINARY AA51881 SERVO MOTOR CONTROLLER ■ PACKAGE DIMENSIONS ■ NOTES ON USE • The specifications for the product described in this document are for reference only. Upon actual use, therefore, please request that specifications to be separately delivered. • The application circuit examples explain typical applications of the products, and do not guarantee the success of any specific mass-production design. • Application circuit diagrams and circuit constants contained herein are shown as examples of standard use and operation. Please pay careful attention to the peripheral conditions when designing circuits and deciding upon circuit constants in the set. • Take account of common impedance when designing the earth line on a printed wiring board. ©Copyright Agamem Microelectronics Inc. 7 www.agamem.com.tw 2008/5/5 AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.