STA6940M Brushed DC Motor Driver IC With PWM Control Features and Benefits Description ▪ Power supply voltage, VBB , 44 V maximum, 10 to 40 V normal operating range ▪ Logic supply voltage, VDD , 3 to 5.5 V compatible ▪ Output current, IO ,4 A average, 8 A maximum ▪ Output elements are all N-channel MOSFETs to reduce losses ▪ Internal charge pump ▪ Forward, reverse, free, and brake control modes available ▪ Constant-current control: ▫ Off-time 35 μs, fixed (Slow Decay mode) ▪ Internal Overcurrent Protection (OCP) circuitry ▫ Off-time 142 μs fixed (Fast Decay mode) ▪ Internal Thermal Shutdown (TSD) circuitry ▪ ZIP type 18-pin fully-molded package (STA package) Combining low-power CMOS-compatible logic with highcurrent, high-voltage power MOSFET outputs, the STA6940M provides complete control and drive for brush DC motors. It provides internal fixed off time, pulse-width modulation (PWM) control of the output current, rated for 4 A normal operating level. The CMOS logic section provides four modes of operation: forward and reverse normal drive rotation, outputs-off free spin (coast), and electronic braking. The innovative multi-chip internal structure separates the main logic IC (MIC) from the four N-channel power MOSFETs. This results in lower thermal resistance and greater efficiency. PWM control allows constant-current control of output while reducing heat generation and power losses by providing fixed off-time dual decay modes. The internal charge pump ensures full power availability for switching. Package: 18-pin ZIP (STA) Not to scale Functional Block Diagram VDD CP 7 14 CP1 CP2 13 12 VBB VBB 18 1 MIC Charge Pump Reg UVLO IN1 IN2 Diag PWM_REF OCP_REF 2 3 5 6 Logic Pre-Driver 17 11 8 9 Comp Comp OSC PWM and OCP Control 10 GND 28106.01 16 Reg 15 Sense2 4 Sense1 OA OA OB OB STA6940M Brushed DC Motor Driver IC With PWM Control Selection Guide Part Number Package Packing STA6940M 18-pin ZIP through hole mount *Contact Allegro for additional packing options 18 pieces per tube Absolute Maximum Ratings Characteristic Symbol Main Supply Voltage Notes Rating Units 44 V 6 V 8 A VBB Logic Supply Voltage VDD Output Current IO(max) ≤ 100 μs Output Voltage VO –1.5 to VBB + 1.5 V Logic Input Voltage VIN –0.3 to VDD + 0.3 V PWM_REF Input Voltage VPREF –0.3 to VDD + 0.3 V OCP_REF Input Voltage VOREF Sensing Voltage VRS Power Dissipation PD Junction Temperature TJ –0.3 to VDD + 0.3 V –1 to 2 V Except tw < 1 μs DC drive 2.7 W PWM drive (Slow Decay) 3.0 W PWM drive (Fast Decay) 3.2 W 150 ºC Operating Ambient Temperature TA –20 to 85 ºC Storage Temperature Tstg –30 to 150 ºC Min. Typ. Max. Unit VBB 10 – 40 V IO – – 4 A 3.0 – 5.5 V Recommended Operating Conditions Characteristic Symbol Main Supply Voltage Output Current Logic Supply Voltage Conditions Transient voltages at VDD pin must not exceed ±0.5 V VDD PWM Reference Input Voltage VPREF Constant-current control – – 1 V OCP Reference Input Voltage VOREF OCP operating – – 2 V Package surface temperature without heatsink – – 85 °C Case Temperature TC Power Derating Curve Allowable Power Dissipation, PD (W) 3.5 3.2 W 3.0 W 3.0 RQJA = 39°C / W 2.7 W 2.5 RQJA = 42°C / W 2.0 RQJA = 46°C / W 1.5 1.0 DC operation PWM (Slow Decay) PWM (Fast Decay) 0.5 0 0 10 20 30 40 50 60 70 80 All performance characteristics given are typical values for circuit or system baseline design only and are at the nominal operating voltage and an ambient temperature, TA, of 25°C, unless otherwise stated. Ambient Temperature, TA (°C) Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 STA6940M Brushed DC Motor Driver IC With PWM Control ELECTRICAL CHARACTERISTICS valid at TA = 25°C, VBB = 24 V, VDD = 5 V; unless otherwise noted Characteristics Main Supply Current Symbol IBB Logic Supply Current IDD Charge Pump Voltage Vcp Charge Pump Switching Frequency Main Supply Undervoltage Protection* Logic Supply Undervoltage Protection* Charge Pump Undervoltage Protection* MOSFET On Resistance MOSFET Body Diode Forward Voltage MOSFET Breakdown Voltage Logic Input Voltage Logic Input Current Test Conditions Operating VBB = 10 to 40 V Typ. Max. Unit – – 20 mA – – 5 mA – VBB + 5 – V fcp – 360 – kHz VUVBL – 7 – V VUVBH – 7.8 – V VUVDL – 2.3 – V VUVDH – 2.5 – V VUVCL – 3.8 – V VUVCH – 4 – V RDS(on) ID = 4 A – 0.1 0.13 Ω VF IF = 4 A – 0.95 – V VDSS 53 – – V VIL – – 0.25 × VDD V VIH 0.75 × VDD – – V IIL – ±1 – μA IIH Maximum Input Frequency Min. fclk PWM_REF Pin Input Voltage VPREF PWM_REF Pin Input Current IPREF – ±1 – μA Clock duty cycle = 50% 100 – – KHz PWM_REF terminal 0.1 – 1.0 V – ±10 – μA 0.1 – 2.0 V – ±10 – μA OCP_REF Pin Input Voltage VOREF OCP_REF Pin Input Current IOREF PWM Sensing Voltage VPSEN Sense1, Sense2 terminals VPREF – 0.045 VPREF – 0.015 VPREF + 0.015 V OCP Sensing Voltage VOSEN Sense1, Sense2 terminals VOREF – 0.045 VOREF – 0.015 VOREF + 0.015 V Sense1, Sense2 Pin Input Current ISENSE Sense1, Sense2 terminals – ±20 – μA VDIAGL IDIAGL = 1.25 mA – – 1.25 V VDIAGH IDIAGH = –1.25 mA VDD – 1.25 – – V Diag Pin Output Voltage Diag Pin Output Current Diag Pin Output Frequency OCP_REF terminal IDIAGL VDIAGL = 0.5 V – – 1.25 mA IDIAGH VDIAGH = VDD – 0.5 V –1.25 – – mA fDIAG During PWM off-time – 90 – kHz PWM Minimum On-Time (Blanking Time) ton(min) – 5 – μs PWM Off-Time tPOFF PWM operating – 35 – μs OCP Minimum On-Time tOON OCP operating – 5 – μs OCP Off-Time tOOFF OCP operating – 142 – μs Crossover Current Delay Timing tCOCD Switching Time 150 – 750 ns tcon Measured from input to output on – 3.0 – μs tcoff Measured from input to output off – 2.7 – μs – 140 – ºC – 115 – ºC Thermal Shutdown Activation Temperature Ttsdon Thermal Shutdown Release Temperature Ttsdoff Package back side surface temperature after case permeated with heat from operation *The outputs will be disabled if any of the three undervoltage protection circuits are operating. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 STA6940M Brushed DC Motor Driver IC With PWM Control Characteristic Data Output MOSFET On-Voltage, VDS(on) Output MOSFET Body Diodes Forward Voltage, VF 0.90 MOSFET Body Diode Forward Voltage, VF, (V) MOSFET On Resaistance, R DS(on), (Ω) 0.17 0.15 0.13 0.11 0.09 0.07 0.05 0 0.85 Single MOSFET 0.80 IO= 4 A 0.75 IO= 3 A 0.70 IO= 2 A 0.65 0.60 IO= 1 A 0.55 0.50 25 50 75 100 125 Junction Temperature, TJ (°C) 150 175 0 25 50 75 100 125 150 175 Junction Temperature, TJ (°C) Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 STA6940M Brushed DC Motor Driver IC With PWM Control Functional Description Control IC (MIC) Functions Regulator The regulator supplies the necessary operating power for the MOSFET gate drivers (see Pre-Driver section) and internal linear circuitry. UVLO The main supply, logic supply, and charge pump all supply necessary operating power for proper operation. If any one of the supplies drop to the preset undervoltage lockout threshold, the outputs will be disabled. Charge Pump The high-side gate pre-driver for the N-channel MOSFETs is powered from this charge pump, which operates at 100 kHz. Pre-Driver This is the gate driver for the output N-channel MOSFETs. It is powered from the charge pump (high-side) or the internal regulator (low side). Current Control and OCP The constant-current control and overcurrent protection circuitry reference the input voltages on Table 1. Input Truth Table, PWM Control Input Output the PWM_REF pin (for constant-current level) and OCP_REF (for overcurrent protection threshold). These functions use a fixed off-time control scheme. OSC The oscillator is used for timing the current-control blanking time and PWM off-time. Logic I/O Terminals Motor Control Input Terminals (IN1, IN2) These are used to control the motor driver outputs to control the behavior of the motor, as shown in table 1. They have been designed with CMOS processes to ensure high input impedance. To help mitigate the effects of noise on these inputs, each terminal is internally fitted with a low-pass filter. These terminals are designed to be used with steady logic inputs (low or high). Diagnostics Output Terminal (Diag) This logic output indicates normal operation, a fault condition, or PWM output off-time, as shown in table 2. To avoid damage, the Diag terminal must not be connected to the GND or supply terminals. Table 2. Diag Terminal Output Motor Function IN1 IN2 OA OB Low Low High Z High Z Free (coast) High Low High Low Forward Low High Low High Reverse High High Low Low Brake Output Indication High • No UVLO protection operating • Outputs ON Pulse (approximately 90 kHz) Low Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com PWM off-time • Any UVLO protection operating • OCP operating • TSD operating 5 STA6940M Brushed DC Motor Driver IC With PWM Control VM Basic Motor Control Functions There are four states of motor output: free (coast), forward, reverse, and brake. This section describes the inputs and the MOSFET outputs that set these states. OFF (A) Free (coast) Free (Coast) This state is set by low signals on both the IN1 and the IN2 logic inputs. All MOSFETs are turned off, and no current flows through the device to the motor. The motor is totally free to spin. The MOSFET states are shown in figure 1(A). OFF OA Motor OB OFF OFF Rs Forward This state is set by a high signal on the IN1 input and a low signal on the IN2 input. The high-side MOSFET on the OA side is turned on, and the low-side MOSFET on the OB side is turned on. Current flows through the device to drive motor rotation (the terms "forward" and "reverse" only serve to indicate opposite relative directions). The MOSFET states are shown in figure 1(B). VM ON (B) Forward Reverse This state is set by a low signal on the IN1 input and a high signal on the IN2 input. The low-side MOSFET on the OA side is turned on, and the high-side MOSFET on the OB side is turned on. Current flows through the device to drive motor rotation (the terms "forward" and "reverse" only serve to indicate opposite relative directions). The MOSFET states are shown in figure 1(C). Brake This state is set by high signals on both the IN1 and the IN2 logic inputs. Both high-side MOSFETs are turned off, and both low-side MOSFETs are turned on. The motor coils are shorted together providing resistance to rotation. The MOSFET states are shown in figure 1(D). OFF OA Motor OB IM OFF ON Rs VM OFF ON OA (C) Reverse Motor OB IM ON OFF Rs VM Figure 1. The panels demonstrate the MOSFET switching conditions and the resulting current flow for each of the four motor control states. OFF OFF OA (D) Brake Motor ON OB ON Rs Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 STA6940M Brushed DC Motor Driver IC With PWM Control VM Constant-Current Control (PWM) When the motor is starting up, the current, IM , increases to the set current limit, as shown in figure 2. During operation, the motor current, IM , is monitored using the voltage across resistor RS , which is compared to the set point VPREF. ONm OFF When the current limit is reached, the device turns-off the highside MOSFET and body-diode of the low-side MOSFET allows the back-EMF current to flow in the coil for 35 μs (Slow Decay mode), as shown in figure 3. After this time expires, the PWM control reverts to on. There is a blanking time of 5 μs during turn-on to prevent malfunction due to noise surges. During the blanking time, the current control does not operate, which means that the minimum on-time is also the blanking time. OFF OA IM_ON Motor OB Slow Decay: 35 μs OFF IM_OFF ON Rs Figure 3. Currrent Control. The current path as current is rising is shown by the solid arrow (IM_ON), the off-time current is shown by the dashed arrow (IM_OFF). Blanking Time ≥5 μ s Off-Time 35 μs I PREF IM 0 VPREF VRS 0 Diag 0 (A) (A) Figure 2. Currrent Control Waveforms. As can be seen at the points (A), PWM timing and Diag pin oscillation are NOT synchronous. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 STA6940M Brushed DC Motor Driver IC With PWM Control Phase PWM Control The current-control method uses fixed off-time and blanking time, as detailed above. Even when the PWM_REF terminal is at a low voltage, however, the current will still flow, and increase, during the blanking time (minimum on-time). This minimal current, because of the fixed off-time, will only decay to a certain point. To enable current control below this minimal current level, the Phase PWM control method must be used. This is different from the PWM current control as detailed above, and external PWM signals with the correct on/off duty cycle must be used. VM ONm OFF OFF OA IM_ON Phase PWM control has two modes, Fast Decay mode and Slow Decay Mode. Motor OB IM_OFF Fast Decay Mode This mode uses the Free motor state. In other words, during recirculation time, the IN1 and IN2 pins are both set low. During motor driving time, the current control point is determined by the duty cycle and frequency of the input signals: OFF ONm OFF Rs • The input PWM signals must have an on-duty cycle greater than 50% for proper operation. • The input PWM signals should have a recommended frequency of 30 to 50 kHz. Motor rotation direction is determined by pulsing one or the other logic input, as shown in table 3. For the forward direction, current flows are shown in figure 4, and the input pulse and resulting current pulsing is shown in figure 5. Another new method of control during recirculation, is to change the inputs shown in table 3, applying low signals instead of high (the pulsed signals remain as in the table). This method allows the driver to dissipate less heat by turning on the MOSFET for the back-EMF current decay instead of using the body diodes. This method is also known as Synchronous Rectifier control. Figure 4. Phase PWM control (Fast Decay mode), current flows shown are for the forward direction IN1 IN2 IM_ON IM_OFF Table 3. Input Truth Table, Phase PWM Control Input IN1 IN2 IM_ON + IM_OFF Motor Function Figure 5. Phase PWM control (Fast Decay mode), logic input pulsing shown for the forward direction Fast Decay Mode PWM pulse Low Forward Low PWM pulse Reverse Slow Decay Mode PWM pulse High Forward High PWM pulse Reverse Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 STA6940M Brushed DC Motor Driver IC With PWM Control Slow Decay Mode This mode uses the Brake motor state. In other words, during recirculation time, the IN1 and IN2 pins are both set high. During motor driving time, the current control point is determined by the duty cycle and frequency of the input signals: • The input PWM signals must have an on-duty cycle less than 50% for proper operation. • The input PWM signals should have a recommended frequency of 30 to 50 kHz. Motor rotation direction is determined by pulsing one or the other logic input, as shown in table 3. For the forward direction, current flows are shown in figure 6, and the input pulse and resulting current pulsing is shown in figure 7. Overcurrent Protection (OCP) In the STA6940M, the overcurrent protection feature is designed to protect against rotor lock or coil short conditions. This protection is triggered when the motor current, IM , as detected by the resistor RS , reaches the set level of OCP_REF. When the OCP threshold is reached, the driver turns-off all MOSFETs for 135 μs (figure 8). The decaying current must flow through the body diodes to the main supply (Fast Decay mode), as shown in figure 9. Note: OCP operation does not disable the driver. OCP is flagged on the Diag pin, and the system logic of the application should control the response. VM IN1 IN2 ONm OFF OFF OA IM_ON IM_ON OB Motor IM_OFF OFFm ON IM_OFF ON IM_ON + IM_OFF Rs Figure 6. Phase PWM control (Slow Decay mode), current flows shown are for the forward direction Figure 7. Phase PWM control (Slow Decay mode), logic input pulsing shown for the forward direction VM Off-time 135 μs IOREF IM ONm OFF OFF OA IM_ON Motor OB V VRS 0 Fast Decay:135 μ s OFF 0 IM_OFF Rs Figure 8. OCP operation (Fast Decay mode) OREF ONm OFF Diag 0 Figure 9. OCP operation waveforms (Fast Decay mode) Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 STA6940M Brushed DC Motor Driver IC With PWM Control The constant-current set point, VPREF , and the OCP threshold, VOREF , may be set individually as needed. VDD D iag (V) • VPREF < VOREF With this relationship, constant-current control has priority. In order for OCP to operate, the OCP condition must be detected before the constant-current control is operating, that is, during the blanking time. During blanking time, the voltage VRS could reach VOREF , initiating OCP. • VOREF < VPREF With this relationship, OCP has priority over constant-current control. At any time while the STA6940M is powered, if the voltage VRS reaches VOREF , OCP can operate. Thermal Shutdown (TSD) This device has internal thermal protection. The thermal shutdown function is of the auto-recovery type. The operating principle is that when the internal control IC (MIC) temperature reaches Ttsdon all outputs are disabled. When the temperature drops below Ttsdoff the device is reenabled. Ttsdoff Ttsdon TC (°C) Figure 10. Thermal shutdown operation provides a hysteresis in supply voltage to the MOSFETs, which is monitored and sets the Diag pin output When the device outputs are disabled, the function sets the Diag terminal low. Figure 10 shows the relationship of Diag output and case temperature, TC. Note: This device utilizes a multi-chip construction, the Control IC (MIC) and four separate MOSFETs. The temperature sensor is located on the control IC, however, the primary heat sources are the MOSFETs. Thus this internal thermal protection cannot react to sudden changes in MOSFET temperature. Undervoltage Protection (UVLO) If any of the voltages of the main supply, VBB , logic supply, VDD , or the charge pump, VCP (VCP -VBB), fall below the preset threshold, the device will be disabled. (The charge pump voltage is derived from VBB using the internal charge pump circuitry and connected capacitors.) The effects on output to the motor and to the Diag pin are shown in figure 11. Note: The VBB and VDD voltage power-up sequence does not affect UVLO operation. VDD VUVDH 0V VBB VUVBH VCP 0V VUVCH 0V Diag 0V Output Off Output Output On Off Output On Output Off Output On Figure 11. Operation of the UVLO circuits Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10 STA6940M Brushed DC Motor Driver IC With PWM Control Application Information VDD = 3 to 5.5 V IN1 CP1 CP2 CP VBB VBB IN2 M ic ro cont r oller CB VDD VBB = 10 to 40 V C2 C1 OA Diag OA STA 6940 M R1 DCM OCP_ REF OB OB R2 R4 R5 CA PWM_REF C3 GND Sense 2 Sense1 R3 Rs Logic Gnd Power Gnd Figure 12. Typical application circuit Reference Component Values R1 = 3 kΩ R2 = 1 kΩ R3 = 1 kΩ R4 = 10 kΩ R5 = 10 kΩ *RS = 0.22 Ω CA = 100 μF / 50 V CB = 10 μF / 10 V C1 = 0.1 μF C2 = 0.1 μF C3 = 0.1 μF *Please choose the proper power rating for RS , taking into consideration the approximate power dissipation, as 2 follows: PD ≈ IO × RS × On Duty Cycle. • Surge voltage less than -1.0 V may occur on OA and OB outputs, therefore Schottky barrier diodes are recommended between those pins and GND • Please take care to reduce noise on the VDD line. • Logic input terminals (IN1 and IN2) which are not externally controlled must not be left open; they should be pulled-up or pulled-down to the VDD or GND terminals, based on the required mode. Otherwise the device may malfunction. • Noise voltages greater than 0.5 V on the VDD line may cause malfunction. Please take special care when laying out the return line and ground pattern. • Unused logic output terminals (Diag) should be left open. • Separating IC GND (pin 10), VDD Gnd (signal ground) and VBB Gnd (power ground) helps reduce noise. • Connecting only one of the Sensex terminals may result in damage to the device. • The Sense1 and Sense2 terminals must be tied together, and then connected to RS . Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11 STA6940M Brushed DC Motor Driver IC With PWM Control PWM Constant-Current Control Setting (R1, R2, R3, RS) The PWM fixed current control set point may be changed by using resistors R1, R2, R3 and RS as shown in figure 12. The formula for calculating Io is as follows: constant-current, but using VOREF: IOCP = VOREF / RS , where IO = VPREF / RS , (1) VOREF = where VPREF = R3 R1 + R2 + R3 × VDD (3) (2) . If VPREF is set below 0.1 V, external factors such as component tolerance and wiring impedances may affect the accuracy of the set current level. The STA6940M uses a fixed off-time control scheme. During the off-time, the energy stored in the motor coils dissipates. If the set current point is too low, the motor current may become discontinuous and the motor torque will be greatly reduced as a result. Please take this into consideration when setting the minimal current level. Although setting such a low current level does not damage the device, the control of the set current level will become worse. This is illustrated in figure 13. OCP Point Setting The formula for setting the OCP point is the similar to that for R2 +R3 R1 + R2 + R3 × VDD . (4) Power Supply (VBB, VDD) On/Off Sequence This device will operate normally regardless of the power-up sequence of the power supplies. Internal Logic Circuitry Connection The following guidelines should be followed when connecting the internal circuitry: • Input Logic Terminals (IN1, IN2) These terminals require a fixed logic level, and when they are unused, they should not be left open. They should be connected to VDD or GND as necessary. • Output Terminal (Diag) The Diag terminal has an internal equivalent circuit as shown in figure 14. Because this is a CMOS circuit structure, if the terminal is not being used it should be left open. VDD STA6940M ESD protection circuitry Output, Ox Large ITRIP VRS 0 Small ITRIP Coil current = 0 Figure 13. Minimum controllable current level Figure 14. Diag terminal equivalent circuit Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 12 Brushed DC Motor Driver IC With PWM Control Thermal Considerations To accurately calculate the losses incurred by the STA6940M, detailed knowledge of the motor characteristics, input waveforms, and dynamic properties of the circuit must all be considered. The formulas below are simplified approximations using worst-case conditions: For constant voltage drive (DC current): 2 Channels, Steady DC Operation 140 120 ΔTJA = 46 × PD 100 ΔTJ (°C) STA6940M 80 60 ΔTJA = 35 × PD 40 PD = IO2 × RDS(on) × 2 , (5) 20 0 and, for constant-current drive (PWM): PD = IO2 × RDS(on) × 2 × 0 tON tON + tOFF + ( IO2 × RDS(on) + VF × IO ) × 0.5 1.0 1.5 2.0 PD (W) 2.5 3.0 3.5 3 Channels, PWM Operation (Slow Decay) tOFF tON + tOFF , 140 (6) 120 where: ΔTJA = 42 × PD 100 ΔTJ (°C) PD is the device power dissipation, IO is the motor current ( ≈ IO), RDS(on) is the internal MOSFET on-resistance, 80 60 ΔTJA = 35 × PD 40 RS is the external sensing resistor, 20 VF is the internal MOSFET body diode forward voltage, 0 tON is the PWM on-time, and 0 0.5 1.0 1.5 tOFF is the PWM off-time. 2.5 3.0 3.5 If a heatsink is being used, the ΔTJA (junction to ambient) as calculated previously will be different because the thermal resistance, RθJA , is different. The new value can be calculated using the heatsink heat resistance RθFIN: 4 Channels, PWM Operation (Fast Decay) 140 120 ΔTJA = 39 × PD 100 ΔTJ (°C) Using the above calculated power dissipation, it is possible to estimate the junction temperature using the curves in figure 15. In the worst conditions (with high ambient temperatures), as long as the junction temperature does not exceed 150ºC the device will not be damaged. However, the actual temperature of the device should be measured along with the junction temperature calculation. 80 60 ΔTJA = 35 × PD 40 20 0 0 RQJA z RQJC + RQFIN = (RQJA – RQCA) + RQFIN 2.0 PD (W) . 0.5 1.0 (7) 1.5 2.0 2.5 3.0 3.5 PD (W) Figure 15. Change in junction temperature versus device power dissipation Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 13 STA6940M Brushed DC Motor Driver IC With PWM Control To extrapolate the junction temperature, ΔTJ , using a measured device temperature, please use the following method: 1. Measure the ambient temperature, TA. 2. With the device mounted but not operating, measure the surface temperature of the device on the back side at the center. 3. Power-on the device, and after it reaches operating temperature, take the measurement again. 4. Subtract the value found in step 2 from the value found in step 3. This provides a value for ΔTCA . 5. Refer to figure 15 and locate the value found in step 4 on the ΔTCA trace. 6. Determine the corresponding power dissipation, PD. 7. Substitute the values into the following equation: ∆TJ ∆TCA + PD × RQJC . (8) Important notes: • Please ensure that the maximum rated junction temperature (150ºC) will not be exceeded. • The information provided above is to be used as reference for the design phase. The actual product must undergo empirical testing to ensure proper thermal design. • The recommended maximum operating temperature for this device, without a heatsink is TC = 80ºC maximum. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 14 STA6940M Brushed DC Motor Driver IC With PWM Control Pin-out Diagram 2 1 Chamfer 4 3 6 5 8 7 10 9 12 11 14 13 16 15 18 17 (Top View) Terminal List Table Number Symbol 1 VBB 2 3 OA 4 Sense1 5 IN1 6 IN2 7 VDD 8 PWM_REF Function Main supply input (motor supply) Motor terminal A Motor current sensing Control mode setting (please see truth table) Logic supply Constant-current setting 9 OCP_REF 10 GND Ground PWM diagnostic and OCP output 11 Diag 12 CP2 13 CP1 14 CP 15 Sense2 16 17 18 Overcurrent setting Connection for charge pump Motor overcurrent sensing OB Motor terminal B VBB Main supply input (motor supply) *The VBB terminals, 1 and 18, are internally connected. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 15 STA6940M Brushed DC Motor Driver IC With PWM Control Package Outline Drawing 25.55 (Includes mold flash) 25.25 ±0.3 Gate protrusion 4 ±0.2 Gate protrusion 9.0 ±0.2 1 REF Branding Area 3.3 ±0.5 6.9 REF 3.6 REF 1.3 ±0.1 B R1 REF +0.2 0.45 – 0.1 0.55 +0.2 – 0.1 2X1.5 ±0.5 1 3 2 A Measured at pin tips B Measured at case base 5 4 7 6 9 8 11 10 1.27 ±0.5 A 13 12 15 14 2.54 ±0.5 A 17 16 18 Terminal core material: Cu Terminal plating: Ni, with Pb-free solder coating Dimensions in millimeters Branding codes (exact appearance at manufacturer discretion): 1st line, type: STA6940M 2nd line, lot: YMDD Where: Y is the last digit of the year of manufacture M is the month (1 to 9, O, N, D) DD is the date Leadframe plating Pb-free. Device composition includes high-temperature solder (Pb >85%), which is exempted from the RoHS directive. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 16 STA6940M Brushed DC Motor Driver IC With PWM Control WARNING — These devices are designed to be operated at lethal voltages and energy levels. Circuit designs that embody these components must conform with applicable safety requirements. Precautions must be taken to prevent accidental contact with power-line potentials. Do not connect grounded test equipment. The use of an isolation transformer is recommended during circuit development and breadboarding. Because reliability can be affected adversely by improper storage environments and handling methods, please observe the following cautions. Cautions for Storage • Ensure that storage conditions comply with the standard temperature (5°C to 35°C) and the standard relative humidity (around 40 to 75%); avoid storage locations that experience extreme changes in temperature or humidity. • Avoid locations where dust or harmful gases are present and avoid direct sunlight. • Reinspect for rust on leads and solderability of products that have been stored for a long time. Cautions for Testing and Handling When tests are carried out during inspection testing and other standard test periods, protect the products from power surges from the testing device, shorts between adjacent products, and shorts to the heatsink. Remarks About Using Silicone Grease with a Heatsink • When silicone grease is used in mounting this product on a heatsink, it shall be applied evenly and thinly. If more silicone grease than required is applied, it may produce stress. • Coat the back surface of the product and both surfaces of the insulating plate to improve heat transfer between the product and the heatsink. • Volatile-type silicone greases may permeate the product and produce cracks after long periods of time, resulting in reduced heat radiation effect, and possibly shortening the lifetime of the product. • Our recommended silicone greases for heat radiation purposes, which will not cause any adverse effect on the product life, are indicated below: Type Suppliers G746 Shin-Etsu Chemical Co., Ltd. YG6260 Momentive Performance Materials, Inc. SC102 Dow Corning Toray Silicone Co., Ltd. Soldering • When soldering the products, please be sure to minimize the working time, within the following limits: 260±5°C 10 s 350±5°C • 3s Soldering iron should be at a distance of at least 1.5 mm from the body of the products Electrostatic Discharge • When handling the products, operator must be grounded. Grounded wrist straps worn should have at least 1 MΩ of resistance to ground to prevent shock hazard. • Workbenches where the products are handled should be grounded and be provided with conductive table and floor mats. • When using measuring equipment such as a curve tracer, the equipment should be grounded. • When soldering the products, the head of soldering irons or the solder bath must be grounded in other to prevent leak voltages generated by them from being applied to the products. • The products should always be stored and transported in our shipping containers or conductive containers, or be wrapped in aluminum foil. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 17 STA6940M Brushed DC Motor Driver IC With PWM Control The products described herein are manufactured in Japan by Sanken Electric Co., Ltd. for sale by Allegro MicroSystems, Inc. Sanken and Allegro reserve the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Therefore, the user is cautioned to verify that the information in this publication is current before placing any order. When using the products described herein, the applicability and suitability of such products for the intended purpose shall be reviewed at the users responsibility. Although Sanken undertakes to enhance the quality and reliability of its products, the occurrence of failure and defect of semiconductor products at a certain rate is inevitable. Users of Sanken products are requested to take, at their own risk, preventative measures including safety design of the equipment or systems against any possible injury, death, fires or damages to society due to device failure or malfunction. Sanken products listed in this publication are designed and intended for use as components in general-purpose electronic equipment or apparatus (home appliances, office equipment, telecommunication equipment, measuring equipment, etc.). Their use in any application requiring radiation hardness assurance (e.g., aerospace equipment) is not supported. When considering the use of Sanken products in applications where higher reliability is required (transportation equipment and its control systems or equipment, fire- or burglar-alarm systems, various safety devices, etc.), contact a company sales representative to discuss and obtain written confirmation of your specifications. The use of Sanken products without the written consent of Sanken in applications where extremely high reliability is required (aerospace equipment, nuclear power-control stations, life-support systems, etc.) is strictly prohibited. The information included herein is believed to be accurate and reliable. Application and operation examples described in this publication are given for reference only and Sanken and Allegro assume no responsibility for any infringement of industrial property rights, intellectual property rights, or any other rights of Sanken or Allegro or any third party that may result from its use. Anti radioactive ray design is not considered for the products listed herein. Copyright © 2009 Allegro MicroSystems, Inc. This datasheet is based on Sanken application note Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 18 STA6940M Brushed DC Motor Driver IC With PWM Control Worldwide Contacts Asia-Pacific China Sanken Electric Hong Kong Co., Ltd. Suite 1026, Ocean Centre, Canton Road Tsimshatsui, Kowloon, Hong Kong Tel: 852-2735-5262, Fax: 852-2735-5494 Sanken Electric (Shanghai) Co., Ltd. Room 3202, Maxdo Centre, Xingyi Road 8 Changning District, Shanghai, China Tel: 86-21-5208-1177, Fax: 86-21-5208-1757 Taiwan Sanken Electric Co., Ltd. Room 1801, 18th Floor, 88 Jung Shiau East Road Sec. 2, Taipei 100, Taiwan R.O.C. Tel: 886-2-2356-8161, Fax: 886-2-2356-8261 Japan Sanken Electric Co., Ltd. Overseas Sales Headquarters Metropolitan Plaza Building, 1-11-1 Nishi-Ikebukuro Toshima-ku, Tokyo 171-0021, Japan Tel: 81-3-3986-6164, Fax: 81-3-3986-8637 Korea Sanken Electric Korea Co., Ltd. Mirae Asset Life Building, 6F 168 Kongduk-dong, Mapo-ku Seoul 121-705, Korea Tel: 82-2-714-3700, Fax: 82-2-3272-2145 Singapore Sanken Electric Singapore Pte. Ltd. 150 Beach Road, #14-03 The Gateway West Singapore 189720 Tel: 65-6291-4755, Fax: 65-6297-1744 Europe Sanken Power Systems (UK) Limited Pencoed Technology Park Pencoed, Bridgend CF35 5HY, United Kingdom Tel: 44-1656-869-100, Fax: 44-1656-869-162 North America United States Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01606, U.S.A. Tel: 1-508-853-5000, Fax: 1-508-853-7895 Allegro MicroSystems, Inc. 14 Hughes Street, Suite B105 Irvine, California 92618, U.S.A. Tel: 1-949-460-2003, Fax: 1-949-460-7837 Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 19