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| ICs for Motor AN6657, AN6657S Micromotor Forward/ Reverse Electronic Governors s Overview 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. AN6657 Unit : mm 1 2 21.70.3 3 4 5 6 7 8 16 15 14 13 12 10 9 s Features * Wide operating supply voltage range ; V CC =4.5V to 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 =20A or less at stop time * Capable of controlling forward/reverse rotation, fast forward/constant speed, and start/stop via 3 input pins 0.51min. 6.30.25 3.80.25 (3.45) 0.3 - + 0.1 5 0.0 3 ~ 15 7.620.25 16-Lead DIP Package (DIP016-P-0300E) s Applications * Speed control * of the micromotors for the radio cas- AN6657S Unit : mm 0.40.25 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. 0.4 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 1.50.2 10.10.3 0.65 0.10.1 1.27 0.3 4.20.3 6.50.3 s Block Diagrom GND 16 15 Drive Mode Swiching Logic 14 13 12 11 VCC 10 9 16-Lead SOP Package (SOP016-P-0300) Ref.Voltage 1k 10k Amp. For./Rev. Drive Circuit 1 2 3 4 5 6 7 8 0.15 2.54 11 0.50.1 1.20.25 AN6657, AN6657S s Absolute Maximum Ratings (Ta= 25C) Parameter Supply Voltage Supply Current Output Current Power Dissipation AN6657 AN6657S AN6657 AN6657S Symbol VCC ICC IO PD Topr Tstg Rating 14.4 50 700 500 380 -20 ~ + 70 -55 ~ +150 -55 ~ +125 ICs for Motor Unit V mA mA mW C C Operating Ambient Temperature Storage Temperature s Recommended Operating Range (Ta = 25C) Parameter Operating Supply Voltage Range Symbol VCC Range 4.5V ~ 14V s Electrical Characteristics (Ta = 25C) Parameter Bias Current Prestart Current Reference Voltage Start Voltage Start Current Rated Load r.p.m Forward/Reverse r.p.m Difference FF/Rated r.p.m. Ratio r.p.m. Characteristics on Voltage Change r.p.m. Characteristics on Load Change Switching Mode Input H Switching Mode Input L Current Limiting Starting Voltage Ref. Voltage Temperature Characteristics Symbol Ibias Istop Vref VCC (S) IST NL NLogi N NV NL VH VL VLim Vr/Ta VCC = 5V VCC = 5V VCC = 5V Supply voltage at which a 50mA current flows to Ra VCC = 4.5V, Ra = 13 VCC = 5V, IL = 55mA, N = 2000rpm VCC = 5V, IL = 55mA, N = 2000rpm VCC = 5V, IL = 55mA, N = 4000rpm VCC = 4.5V ~ 9V, IL = 55mA VCC = 4.5V, IL = 55mA ~ 90mA VCC = 5V ~ 14V VCC = 5V ~ 14V VCC = 9V, RT = 1.3 VCC = 5V, Ta = 0C ~ 60C 3 0 0.55 0.62 0.015 130 -10 -5 1.85 0 0 2 10 5 2.15 50 120 6 0.7 0.7 1.1 1.3 Condition min. typ. 4 max. 10 20 1.5 3 Unit mA A V V mA % % Times rpm/V rpm V V V %/C s Application Circuit To Mechanism Controller, etc VCC + 1.2 NC 16 15 14 13 12 11 10 9 3900 rpm/C - 4.7F AN6657, AN6657S 1 2000 rpm/C 15k 1kB + - 2 4.3k 3 4 0.022F 5 6 7 8 2SD2249 or 2SD2177 680 0.01F M HKN-3A6LDI (Ra=13) (National Micromotors Co., Ltd) ICs for Motor s Pin Descriptions Pin No. 1 Pin Name Constant Speed Setting Description Constant speed setting pin I/O O Voltage VCC - 1.3V 11 2 2 FF Setting FF speed setting pin O VCC - 1.3V 1 AN6657, AN6657S Equivalent Circuit VREF 3 3 Speed Control Controls the speed I 4 Phase Compensation Oscillation preventive phase compensation pin I 5 Motor Drive + Motor + pin connection pin O 11 5 8 9 6 Collector Connection Collector connection pin of the external NPN transistor Base connection pin of the external NPN transistor O 7 Base Connection O 4 O 50 8 Motor Drive - Load Characteristics Setting VCC Moror - pin connection pin 6 9 Motor torque load characteristics setting pin O 150 7 70k 10 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 40k 14 15 30k 16 Constant Speed/FF Constant speed/FF control pin I 16 AN6657, AN6657S s 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) 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 ICs for Motor 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 VCC + Constant Speed/ Fast Forward Forward/ Reverse S/S 1 r1 < 10 Ra 4.7F - NC 16 15 14 13 12 11 10 9 Drive Mode Switching Logic Reference Voltage Forward/ Reverse Drive Circuit r2 2SD2249 or 2SD2177 r3 1k 10k Amp. 1 15k 1kB r5 680 r6 2 4.3k 3 1 4 0.022F 5 6 7 8 r4 2SD2249 or 2SD2177 + M 2 - = 0.01F Ea 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 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). AN6657, AN6657S * Setting the External Resistor r1 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. * 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 (20A) is available. 3) Setting the motor speed The motor speed at constant speed time can be expressed by the expression (4). VREF r2+r3 r3 * r5 r4 * r6 r r4+r6 + 5 Low Temperature Normal Temperature N (R.P.M.) High 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 + 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 Pin14 L H H H H Pin15 -- H L H L Pin16 -- L L H H Pin5 Motor + -- H L H L Output Pin8 Motor - -- L H L H Pin2 OFF OFF OFF ON ON Motor Drive Mode Power OFF (pause) Forward (constant speed) Reverse (constant speed) FF REW AN6657, AN6657S * Current Limiting Function All Temperatures N (R.P.M.) ICs for Motor 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 = VLim r1 (8) * 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 : VBEON Voltage < 0.6V When r1 = 1.2, from the expression (8) ILim is ; 0.6V ILim = = 500mA 1.2 s Characteristics Curve PD - Ta 800 FF/REW r.p.m. Load Torque 4000 Power Dissipation PD (mW) 600 R.p.m. N (rpm) AN6657 400 Constant Speed 2000 VCC = 9V VCC = 6V AN6657S 200 0 0 40 80 120 160 0 0 40 80 Load Torque T (g - cm) 120 160 Ambient Temperature Ta (C) |
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