ICs for Motor AN6657, AN6657S Micromotor Forward/ Reverse Electronic Governors ■ Overview AN6657 16 2 15 3 14 4 13 5 12 6 11 supply voltage range ; V CC =4.5V to 7 10 14V • Stable reference voltage (1.3V) and easy speed control • Large starting torque and maximum control torque • Good secular drift because of external power transistor • Provided with the motor stop function ; ICC =20µA or less at stop time • Capable of controlling forward/reverse rotation, fast forward/constant speed, and start/stop via 3 input pins 8 9 3 ~ 15˚ 7.62±0.25 16-Lead DIP Package (DIP016-P-0300E) AN6657S 15 3 14 4 13 5 12 6 11 7 10 8 9 0.3 0.65 1.5±0.2 16 2 0.1±0.1 1 10.1±0.3 Unit : mm 0.15 settes Speed control of the micromotors for the microcassettes of the automatic answering telephone sets • Control of the tape loading motors for the DATs, etc. • + 0.1 5 0.0 0.3 – 0.4 of the micromotors for the radio cas- (3.45) 3.8±0.25 0.4±0.25 ■ Applications • Speed control 0.51min. 6.3±0.25 1.27 ■ Features • Wide operating 21.7±0.3 1 0.5±0.1 1.2±0.25 Unit : mm 2.54 The AN6657 and the AN6657S are the electronic governors capable of controlling the forward/reverse speed, fast forward, rewind, and start/stop of the micromotors used for the radio/cassette tape recorders, automatic answering telephone sets, and so on. 4.2±0.3 6.5±0.3 ■ Block Diagrom 16-Lead SOP Package (SOP016-P-0300) GND 16 15 14 13 Drive Mode Swiching Logic 12 VCC 11 10 9 Ref.Voltage 1kΩ For./Rev. Drive Circuit 10kΩ Amp. 1 2 3 4 5 6 7 8 ICs for Motor AN6657, AN6657S ■ Absolute Maximum Ratings (Ta= 25˚C) Symbol Rating Supply Voltage Parameter VCC 14.4 Supply Current ICC 50 mA IO 700 mA Output Current Power Dissipation AN6657 Storage Temperature AN6657 –20 ~ + 70 ˚C –55 ~ +150 Tstg AN6657S mW 380 Topr Operating Ambient Temperature V 500 PD AN6657S Unit ˚C –55 ~ +125 ■ Recommended Operating Range (Ta = 25˚C) Parameter Symbol Range Operating Supply Voltage Range VCC 4.5V ~ 14V ■ Electrical Characteristics (Ta = 25˚C) Parameter Symbol Condition Bias Current Ibias VCC = 5V Prestart Current Istop VCC = 5V Reference Voltage Vref VCC = 5V Start Voltage VCC (S) min. typ. max. 4 1.1 1.3 mA 20 µA 1.5 V 3 Supply voltage at which a 50mA current flows to Ra Unit 10 V Start Current IST VCC = 4.5V, Ra = 13Ω 130 Rated Load r.p.m NL VCC = 5V, IL = 55mA, N = 2000rpm –10 0 10 ∆NLogi VCC = 5V, IL = 55mA, N = 2000rpm –5 0 5 % FF/Rated r.p.m. Ratio ∆N VCC = 5V, IL = 55mA, N = 4000rpm 1.85 2 2.15 Times r.p.m. Characteristics on Voltage Change ∆NV VCC = 4.5V ~ 9V, IL = 55mA r.p.m. Characteristics on Load Change ∆NL Switching Mode Input H VH VCC = 5V ~ 14V Switching Mode Input L VL VCC = 5V ~ 14V Forward/Reverse r.p.m Difference Current Limiting Starting Voltage VLim Ref. Voltage Temperature Characteristics ∆Vr/Ta mA 50 rpm/V 120 rpm 3 6 V 0 0.7 V VCC = 4.5V, IL = 55mA ~ 90mA 0.55 VCC = 9V, RT = 1.3Ω 0.62 0.015 VCC = 5V, Ta = 0˚C ~ 60˚C ■ Application Circuit To Mechanism Controller, etc VCC + 3900 rpm/˚C 1.2Ω – 4.7µF NC 16 15 1 2 14 13 12 11 10 9 7 8 AN6657, AN6657S 2000 rpm/˚C 15kΩ 3 4 5 6 2SD2249 or 2SD2177 4.3kΩ 0.022µF 1kB – + M 680Ω 0.01µF % HKN–3A6LDI (Ra=13Ω) (National Micromotors Co., Ltd) 0.7 V %/˚C ICs for Motor AN6657, AN6657S ■ Pin Descriptions 1 Description I/O Voltage Constant speed setting pin O VCC – 1.3V Pin Name Pin No. Constant Speed Setting Equivalent Circuit 11 VREF 2 2 FF Setting FF speed setting pin O 3 Speed Control Controls the speed I 4 Phase Compensation Oscillation preventive phase compensation pin I 5 Motor Drive + Motor + pin connection pin O VCC – 1.3V 1 3 11 6 Collector Connection Collector connection pin of the external NPN transistor O 7 Base Connection Base connection pin of the external NPN transistor O Motor Drive – Moror – pin connection pin O 9 Load Characteristics Setting Motor torque load characteristics setting pin O 10 VCC VCC pin I 11 To the pin 9. Connect to the pin o. O 12 GND GND pin I 13 NC No connection 14 Start/Stop Start/stop control pin I 15 Forward/Reverse Forward/reverse control pin I 9 6 50Ω 150Ω 7 70kΩ 40kΩ 14 15 Constant Speed/FF 8 4 8 16 5 Constant speed/FF control pin I 16 30kΩ ICs for Motor AN6657, AN6657S ■ Supplementary Explanation • Principle of Functioning The AN6657 and the AN6657S are the electronic governors which control the motor speed constantly by making use of the fact that the counter electromotive force generated in the motor winding is proportional to the motor speed when the DC motor rotates. They have two motor drive systems which correspond to the forward and reverse rotations, respectively. The inter-pin voltage of the motor Em is given by the following expression. Em = Ea + Ra Ia (1) Ea : Motor reverse electromotive voltage Ra : Motor internal resistor Ia : Motor current There are the following relationships between the motor reverse electromotive voltage Ea and Motor speed, and motor torque T and motor current Ia, respectively. Ea = Ka · N (2) T = KT · Ia (3) speed signal. In Fig. 1, the motor speed N (∝ motor generated voltage Ea) in the motor control state can be expressed by the following formula. r5 r2 + r3 r1r2 Ea = VREF r · + r3 – Ra Ia 3 r4 + r5 + VCE SAT1 (4) The expression (4) applies in case of motor forward rotation, in which a current flows from the motor + pin (5) to the motor – pin (8). The following expression applies in case of motor reverse rotation, in which a current flows form the motor – pin (8) to the motor + pin (5). Ea = VREF r5 r2 + r3 · + r3 r4 + r5 r1r2 r3 – Ra Ia +VCE SAT2 (5) VREF : Reference voltage, Ra : Motor internal resistor Ia : Motor current r2, r3 : Diffusion resistance in the IC, r4, r5 : Resistance for speed control r1 : Torque control Resistance VCE SAT1 : Forward/reverse drive circuit saturation voltage when motor forward rotation is set VCE SAT2 : Forward/reverse drive circuit saturation voltage when motor reverce rotation is set Ka : Motor generation constant KT : Motor torque constant In the expression (1), the inter-pin voltage of the motor Em includes the voltage Ra · Ia which changes depending on motor current Ia. The counter electromotive voltage Ea is taken out by configuring the bridge circuit and used as a motor VCC + Constant Speed/ Fast Forward Forward/ Reverse 1 r1 < 10 Ra S/S 4.7µF – NC 16 15 14 13 Drive Mode Switching Logic 12 11 10 9 Reference Voltage Forward/ Reverse Drive Circuit r3 1kΩ 10kΩ r2 Amp. 2SD2249 or 2SD2177 1 r4 15kΩ 1kB 2 r6 3 4.3kΩ 4 1 0.022µF 5 6 2SD2249 or 2SD2177 7 + 8 = M r5 680Ω 2 Ea – 0.01µF Ra Ra : Motor-coiled resistor Ea : Motor counter electromotive voltage 1 : Oscillation preventive capacitor 2 : Prevention of motor noise Fig.1 AN6657/AN6657S Motor Control Basic Circuit ICs for Motor AN6657, AN6657S As it is clear from the expression (4), r1r2/r3 – Ra = 0, that is, when r1 = r3/r2÷Ra is established, Ea (∝ motor speed N) becomes a constant value without depending on the motor current Ia (load torque T). This is also true for the expression (5). • Switching the Various Modes The AN6657 and the AN6657S have five motor drive modes as shown in Table 1. Those modes can be selected depending on the voltage H (3V to 6V) and voltage L (0V to 0.7V) signals applied to the input pins14, 15 and 16. 1) Forward/reverse switching : Forward/reverse rotation is switched over whether a current flows from the pin5 to the pin8 (forward rotation) or vice versa (reverse rotation). 2) Power-off (pause) mode : turning off the constant current source inside the IC stops a current to the motor and stops motor. In this mode, all the transistors of the IC are turned off and only a leak current (20µA) is available. 3) Setting the motor speed The motor speed at constant speed time can be expressed by the expression (4). The torque control resistance r1 is important in setting the motor rotating state. Select the resistance which satisfies the condition of the expression (7) within a working temperature range. If this condition is not satisfied, the motor may have abnormal rotation such as hunting, etc. r3 r1 < r2 Ra ≈ (r3/r2 = 1/10 for the AN6657, AN6657S) (7) Ra is the copper coiled resistor of the motor and has the temperature characteristics of + 3,900r.p.m/˚C, Therefore, it is necessary to set the value of r1 so that the relationship in the expression (7) will be satisfied at the minimum working temperature. The diffusion resistance r3/r2 in the IC has the flat temperature characteristics, and if the temperature characteristics of r1 is adjusted to that of Ra, + 3900 r.p.m/˚C, the value of the second term (r1r2r – Ra) of the expressions (4) and (5) shows the flat temperature characteristics and the torque characteristics of the motor speed becomes constant without depending on a temperature. Fig. 2 and Fig. 3 show this relationship. r5 r4 · r6 r r4+r6 + 5 Low Temperature Normal Temperature In the FF (REW) mode, the pin2 is turned on and the first term of the expression (4) is ; Ea =VREF r2+r3 r3 r5 + · r4 · r6 r5 r4+r6 + High Temperature N (R.P.M.) r2+r3 r3 · VREF • Setting the External Resistor r1 r1r2 r3 – Ra Ia TM (Torque) + VCE SAT (6) and the motor speed N (motor generated voltage Ea) is expressed as follows. From the expression (4), the motor speed at constant speed can be controlled with r4 and r5 (external VRs). From the expression (6), the motor speed at the FF (REW) mode can be controlled with r6. Fig. 2 r1 Temperature Characteristics < Ra Temperature Characteristics Table 1 AN6657/AN6657S Mode Switching Table Input Output Motor Drive Mode Pin14 Pin15 Pin16 Pin5 Motor + Pin8 Motor – Pin2 L — — — — OFF H H L H L OFF Forward (constant speed) H L L L H OFF Reverse (constant speed) H H H H L ON FF H L H L H ON REW Power OFF (pause) ICs for Motor AN6657, AN6657S • Current Limiting Function N (R.P.M.) All Temperatures TM (Torque) Fig. 3. r1 Temperature Characteristics = Ra Temperature Characteristics The current limitting function detects the voltage drop of the torque control resistance r1, operates the PNP transistor, and controls the input voltage of the amplifier in the IC to limit the current. Limiting the current can reduce the useless current at start and motor lock time and prevent the supply voltage from dropping. The limited current ILim is calculated by the following expression. ILim = • Temperature Compensation of Motor Speed For the normally used motor with core, the temperature compensation of the motor speed can be done by using 3,900 r.p.m/˚C metal coated or coiled resistor as the torque control resistance r1, and metal coated resistor with a positive temperature coefficient of about 2,000r.p.m/˚C as the speed control resistance r4. VLim r1 (8) VLim : VBEON Voltage < 0.6V When r1 = 1.2Ω, from the expression (8) ILim is ; 0.6V ILim = = 500mA 1.2Ω ■ Characteristics Curve PD – Ta r.p.m. Load Torque 800 FF/REW 600 R.p.m. N (rpm) Power Dissipation PD (mW) 4000 AN6657 400 Constant Speed 2000 AN6657S VCC = 9V 200 VCC = 6V 0 0 40 80 120 Ambient Temperature Ta (˚C) 160 0 0 40 80 Load Torque T (g – cm) 120 160