DRV8307EVM

User's Guide SLVUA58 – April 2014 DRV8307 User’s Guide This document is provided with the DRV8307 customer evaluation module (EVM) as a supplement to the DRV8307 datasheet (SLVSCK2). It details the hardware implementation of the EVM. 1 2 3 Contents Printed-Circuit Board (PCB) (Top 3D View) .............................................................................. Introduction ................................................................................................................... 2.1 Power Connectors .................................................................................................. 2.2 Test Points ........................................................................................................... 2.3 Jumpers .............................................................................................................. 2.4 SPEED ADJUSTMENT (JP6) Jumper and (R20) Potentiometer ............................................. 2.5 Operation of the EVM .............................................................................................. Schematic and Bill of Materials ............................................................................................ 2 2 2 3 4 7 8 9 List of Figures 1 DRV8307EVM Top View .................................................................................................... 2 2 DRV8307EVM Test Points and FAULTn LED ........................................................................... 3 3 DRV8308EVM Jumpers..................................................................................................... 4 4 Hall PWR/GND Circuits ..................................................................................................... 5 5 Circuit when Setting Hall Power to “Current”............................................................................. 5 6 Switching Logic to Support Single-Ended and Differential-Hall Signals .............................................. 6 7 SPEED Adjustment Configuration ......................................................................................... 7 8 DRV8307EVM Schematic .................................................................................................. 9 List of Tables 1 Jumper Descriptions ......................................................................................................... 4 2 Hall Sensors .................................................................................................................. 6 3 DRV8307EVM Bill of Materials ........................................................................................... 10 SLVUA58 – April 2014 Submit Documentation Feedback DRV8307 User’s Guide Copyright © 2014, Texas Instruments Incorporated 1 Printed-Circuit Board (PCB) (Top 3D View) 1 www.ti.com Printed-Circuit Board (PCB) (Top 3D View) Figure 1 illustrates the top view of the DRV8307 EVM PCB. Figure 1. DRV8307EVM Top View 2 Introduction The DRV8307EVM is a solution for evaluating the DRV8307, a brushless DC motor controller. It includes a TLC555 timer configuration to supply PWM to the DRV8307, a potentiometer to adjust the speed of the motor by varying the duty cycle of the PWM, and an external PWM input pin. The EVM also supports differential and single-ended hall sensors. The EVM includes surface-mounted test pins for all important signals on the board. The DRV8307EVM is configured so that only connections to the motor, hall sensors and power supply are required. 2.1 Power Connectors The DRV8307EVM uses a single power supply rail which must be connected to terminal P1. Minimum recommended VM of the EVM is 8.5 V and maximum is 32 V, with a current of at least 2A. A higher current setting is recommended to maintain a stable VM voltage. Please refer to the DRV8307 datasheet (SLVSCK2) for complete voltage range information. When power is supplied to the board, a green LED (D4) in the lower left corner should light up. 2 DRV8307 User’s Guide SLVUA58 – April 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Introduction www.ti.com 2.2 Test Points Test points are provided and labeled according to the inputs and outputs of the DRV8307 device. The signals brought out to test points are labeled HALLOUT, FAULTn, LOCKn, ENABLE, HU+/-, HV+/- HW+/and GND (Figure 2). Figure 2. DRV8307EVM Test Points and FAULTn LED The HALLOUT signal represents the motor speed and phase information. RPM = (HALLOUT × 60) / pole pairs (1) The FAULTn and LOCKn signals represent DRV8307 outputs and indicate a fault or lock condition of the driver or motor. If there is a fault condition present, a red LED (D3) lights up. LOCKn indicates whether the speed loop is locked. The HU+/-, HV+/- HW+/- represent the corresponding hall signals. The ENABLE pin represents whether the DRV8307 is active or off. The ENABLE signal is active low. The DRV8307 can be disabled by applying a high voltage to this pin. SLVUA58 – April 2014 Submit Documentation Feedback DRV8307 User’s Guide Copyright © 2014, Texas Instruments Incorporated 3 Introduction 2.3 www.ti.com Jumpers Seven jumpers (JP1–JP7) are installed by default on the EVM. Table 1. Jumper Descriptions Jumper Description JP1 HALL POWER: Hall sensor power is “5V” or “current” JP2 JP3 HALL SIGNALS: Hall Signals are “Differential” or “Single Ended” JP4 JP5 DIRECTION: Motor direction is “forward” or “reverse” JP7 BRAKE: Motor brake “ON” or “OFF” JP6 SPEED: Speed input is from supplied “external” or “potentiometer” The default jumper settings are JP1 2-3, JP2, JP3 1-2, JP4 2-3 and JP5, JP6, JP7 all installed. This supports "inverse" single-ended hall sensors supplied with 5 V. Speed is supplied from the potentiometer and the motor spins in a forward direction and is not braked. Figure 3. DRV8308EVM Jumpers 4 DRV8307 User’s Guide SLVUA58 – April 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Introduction www.ti.com 2.3.1 HALL POWER Configuration (JP1/JP2 ) Jumpers Sensored BLDC motors typically use either Hall ICs or Hall elements. Most ICs can use 5-V power, while elements typically have power pins that have an equivalent circuit of a resistor, and current must be limited to about 10 mA. In order to support both Hall sensor types the hall power needs to be configured on the DRV8307EVM. When installing JP1 2-3 and JP2, a 5-V power is supplied to terminal P3 to power the ICs. The used (VREG) voltage is only present when DRV8307 is enabled and regulated from VM (Figure 4). Figure 4. Hall PWR/GND Circuits By installing JP1 1-2 and uninstalling JP2, the circuit illustrated in Figure 5 is available for the Hall elements. The used (VSW) voltage is only present when DRV8307 is enabled. VSW equals VM. Hall Elements VM 180 Ÿ HGND HPWR 2 kŸ VSW DRV8307 Figure 5. Circuit when Setting Hall Power to “Current” The current can be calculated as follows: If VM is 24 V, and 3 Hall elements having a resistance of 400 Ω are connected in parallel, 10.4 mA is supplied. Always refer to your Hall element specifications to understand the proper current. The purpose of the 180-Ω resistor is to bias-up the common mode voltage of Hall element differential signals, since the DRV8307 requires VICM between 1.5 V to 3.5 V. If you are unsure of your motor’s Hall type, measure the resistance between the Hall power and ground wires. If it is < 250 Ω, they are likely Hall elements. Hall sensors are easily damaged if incorrect power is applied. 2.3.2 HALL SIGNAL Configuration (JP3/JP4) Jumpers Hall sensors output either a differential signal pair, or a single-ended signal. You can tell which type your motor uses simply by counting the number of wires; a sensored BLDC typically has 3 phase wires, 2 Hall power wires, and 3 or 6 Hall signal wires, so 8 total means single-ended, and 11 total means differential. The DRV8307 has differential comparators on the Hall inputs, and they can also accommodate singleended signals with the use of a few passive components. When using differential Halls, directly connect the 6 Hall signals to the DRV8307 pins. When using single-ended Halls, they require pull-ups. The DRV8307 comparator “-” pins should be biased with a middle voltage, so that a single-ended swing on the “+” pin is detected like a differential voltage. Connect single-ended hall wires to the "+" pins at P3 for normal Hall sensor types or to "-" pins for inverse Hall sensors. SLVUA58 – April 2014 Submit Documentation Feedback DRV8307 User’s Guide Copyright © 2014, Texas Instruments Incorporated 5 Introduction www.ti.com In order to support both single ended and differential hall signals on the DRV8307EVM, the circuit in Figure 6 is implemented: 5V 5V 1 2V Terminal P3 Switch A JP3 Switch A 2 DRV8307 Switch B Block H+ IN 3 Switch D HALL_U+ 5V Switch C 2V 5V 1 Switch A Block HIN Switch B Switch B JP4 Switch C 2 HALL_U3 Switch D Figure 6. Switching Logic to Support Single-Ended and Differential-Hall Signals Table 2 shows the configuration possibilities supporting a variety of hall sensors. Table 2. Hall Sensors 2.3.3 Configuration JP3 JP4 Comment Terminal Installation Differential Hall (Normal) 1-2 1-2 Switches A+B open Hall wires in normal order Differential Hall (Inverse) 1-2 1-2 Switches A+B open Swap external Hall wires Single Ended (Normal) 2-3 2-3 Switch A closed, B open Hall wires to "+" pins Single Ended (Inverse) 1-2 2-3 Switch A open, B close Swap external Hall wires and connect to "-" pins RESERVED 2-3 1-2 NOT ALLOWED DIR Direction (JP5) Jumper Installing the jumper JP5 connects the DIR pin on the DRV8307 to GND. When the DIR pin is tied to GND, the DRV8307 connected motor is set to spin in the forward direction. When removed, the pin is pulled high and the motor spins in the reverse direction. 2.3.4 BRAKE (JP7) Jumper Installing the jumper JP7 connects the BRAKE pin on the DRV8307 to GND. When the BRAKE pin is tied to GND, the DRV8307 connected motor is spinning normal without any brake action. When removed, the pin is pulled high and the motor will be braked by the DRV8307 brake functionality. 6 DRV8307 User’s Guide SLVUA58 – April 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Introduction www.ti.com 2.4 SPEED ADJUSTMENT (JP6) Jumper and (R20) Potentiometer The DRV8307 has a dedicated speed input pin (PWM) that supplies a duty cycle to the DRV8307 to control motor speed. Figure 7. SPEED Adjustment Configuration The DRV8307EVM offers two possibilities to supply this PWM input, controlled by jumper JP6. Installing JP6 uses the speed adjust potentiometer SPEED ADJUST (R20) as shown in Figure 7 as PWM speed input. The potentiometer adjusts the duty cycle of the PWM signal which, in turn, adjusts the speed of the motor. The lower the duty cycle, therefore, the lower the speed, by turning the potentiometer counter-clockwise. In order to increase the duty cycle, thus increase the speed, turn the potentiometer clockwise. The onboard PWM signal for the DRV8307 is generated by a circuit based upon TI's TLC555 Low-Power Timer. It is capable of approximately a 25-kHz output that can be adjusted from 5% to 95% duty cycle. This square output signal will switch from 0 V to VREG. In order to provide an external PWM signal to the DRV8307, remove JP6 and connect the external PWM signal to JP6 pin 1 and the GND pin next to it. For more information on the PWM input required by the DRV8307, please refer to the DRV8307 datasheet (SLVSCK2). SLVUA58 – April 2014 Submit Documentation Feedback DRV8307 User’s Guide Copyright © 2014, Texas Instruments Incorporated 7 Introduction 2.5 www.ti.com Operation of the EVM The following steps provide instructions for the operation of the EVM: 1. Connect a three-phase BLDC motor to terminal P2. 2. Connect the hall signals, either single ended or differential, to terminal P3. 3. Configure JP1-JP4 in order to supply the hall signals in the right manner to the DRV8307. 4. Adjust the Speed potentiometer, R20, to minimum voltage by turning it all the way counterclockwise. This minimizes the motor speed. Otherwise, connect your external PWM input to the JP6 PWM pin. 5. Check JP5 and JP7 to be installed. 6. Apply power to VM terminal P1. 7. Adjust the potentiometer clockwise or turn your external PWM source ON to increase the speed of the motor, continue adjusting as desired. 8. To change direction, uninstall JP5. 9. To start braking, uninstall JP7. 8 DRV8307 User’s Guide SLVUA58 – April 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Schematic and Bill of Materials www.ti.com 3 Schematic and Bill of Materials Figure 8 illustrates the DRV8307EVM schematic and Table 3 is the DRV8307EVM BOM. Jumper List VM P1 2 1 D4 Green Test Points Single Ended HALL normal / inverse TP1 TP2 JP5 Direction Installed is Low JP7 Brake Installed is Low TP3 TP4 TP5 TP6 Speed Adjust JP8 1 HU- 1 HU+ 1 HV- 1 HV+ 1 HW- 1 TP7 TP8 TP9 TP10 TP11 U14 1 ENABLE# 1 HALLOUT 1 VM 1 LOCKn 1 FAULTn TP13 1 1 2 JP3 JP4 2 D6 1.5SMC33 C1 220uF Power input OSTTA024163 C2 0.1uF GND 1 KA 1 Hall power: 5V or current 2 JP1 JP2 R15 4.3K GND U13 1 2 OPTIONAL: Serial Resistors slow FET turn-on time and reduce noise HW+ Installed: R20 Poti controls speed Uninstalled: Ext. PWM input to JP6 GND Default to populate: UHS_GATE R24 240 ULS_GATE R25 0 D1 U2 1 2 3 4 S1 G1 S2 G2 JP1_2-3, JP2 JP3_1-2, JP4_2-3 JP5, JP7, JP8 D1 D1 D2 D2 G1 8 7 6 5 S1 U D2 G2 CSD88537ND S2 U3 These circuits control whether pullup resistors and 2V biases are connected to the DRV8307 Hall inputs. Configuration is done by 2 jumpers (JP3, JP4), and it's provided to support differential Hall signals and single-ended Hall signals with any High/Low polarity. The purpose of the 2V bias is to connect to one end of each DRV8307 differential comparator, so that the single-ended signal swings 0V to 4V and is detected like a differential voltage. In general, if the resistance between the Hall PWR and GND wires is