UM1685 STMICROELECTRONICS | Alldatasheet
Document overview
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Technical content
Datasheet sections
- 1 Boards description
- 1.1 EVAL6480H
- 1.2 EVAL6482H
- 2 Evaluation environment setup
- 3 Device configuration
- 3.1 Voltage mode driving (EVAL6480H)
- 3.2 Advanced current control (EVAL6482H)
- 3.3 Gate drivers
- 3.4 Overcurrent and stall detection thresholds
- 3.5 Speed profile
- 4 Sensing resistors of the EVAL6482H
- 5 How to change the supply configuration of the board
- 6 Daisy chaining
- 7 Revision history
EVAL6480H and EVAL6482H: high power microstepping motor drivers Introduction The EVAL6480H and EVAL6482H are two demonstration boards based on L648x devices implementing a complete stepper motor driver for high power applications. They are designed to operate with a supply voltage ranging from 10.5 V to 85 V and mount eight STD25NF10 MOSFETs with a maximum current of 25 A r.m.s.. In combination with the STEVAL-PCC009V2 demonstration board and the SPINFamily evaluation tool, the boards provide a complete and easy to use evaluation environment allowing the user to investigate all the features of the L648x devices. Both the boards support the daisy chain configuration making them suitable for the evaluation of the devices in multi motor applications.
1 Boards description
1.1 EVAL6480H
Figure 1. EVAL6480H - jumper and connector location Table 1. EVAL6480H - electrical specifications
- Refer to STD25F10 datasheet for details.
- All logic inputs are 5 V tolerant.
Table 2. EVAL6480H - jumper and connector description Table 3. EVAL6480H - master SPI connector pinout (J3)
1 Open drain output L6480 BUSY output
2 Open drain output L6480 FLAG output
3 Ground Ground
4 Supply EXT_VDD (can be used as external logic power supply)
5 Digital output SPI master IN slave OUT signal (connected to the L6480
6 Digital input SPI serial clock signal (connected to L6480 CK input)
7 Digital input SPI master OUT slave IN signal (connected to L6480 SDI
8 Digital input SPI slave select signal (connected to L6480 CS input)
9 Digital input L6480 step-clock input
10 Digital input L6480 standby/reset input
Table 4. EVAL6480H - slave SPI connector pinout (J4)
5 Digital output SPI master IN slave OUT signal (connected to pin 5 of J3)
7 Digital input SPI master OUT slave IN signal (connected to L6480 SDO output)
Figure 2. EVAL6480H - schematic part 1/2
2 JP7
Figure 3. EVAL6480H - schematic part 2/2
Table 5. EVAL6480H - bill of material
Table 5. EVAL6480H - bill of material (continued)
1.2 EVAL6482H
Figure 8. EVAL6482H - jumper and connector location Table 6. EVAL6482H - electrical specifications
- Limited by the mount ed sensing resistors.
- Refer to STD25NF10 datasheet for details.
- All logic inputs are 5 V tolerant.
Table 7. EVAL6482H - jumper and connector description Table 8. EVAL6482H - master SPI connector pinout (J3)
1 Open drain output L6482 BUSY output
2 Open drain output L6482 FLAG output
5 Digital output SPI master IN slave OUT signal (connected to the L6482 SDO
6 Digital input SPI serial clock signal (connected to L6482 CK input)
7 Digital input SPI master OUT slave IN signal (connected to L6482 SDI input)
8 Digital input SPI slave select signal (connected to L6482 CS input)
9 Digital input L6482 step-clock input
10 Digital input L6482 standby/reset input
Table 9. EVAL6482H - slave SPI connector pinout (J4)
7 Digital input SPI master OUT slave IN signal (connected to L6482 SDO output)
Figure 9. EVAL6482H - schematic part 1/2
Figure 10. EVAL6482H - schematic part 2/2
Table 10. EVAL6482H - bill of material
Table 10. EVAL6482H - bill of material (continued)
UM1685 Evaluation environment setup
2 Evaluation environment setup
The evaluation environment is composed by: One or more EVAL6480H or EVAL6482H device One STEVAL-PCC009V2 demonstration board A USB cable A stepper motor with a small mechanical load (unloaded stepper motors suffer of strong resonance issues) A power supply with an output voltage within the operative range of the evaluation board A PC with a Microsoft© Windows® 7 or Windows XP operating system and with a free USB port The SPINFamily evaluation tool (the last version can be downloaded from the STMicroelectronics® website). In order to start using the evaluation environment the following steps are required: 1. Install the SPINFamily evaluation tool. 2. Start the SPINFamily evaluation tool (by defau lt it is in Start menu > All programs > STMicroelectronics > SPINFamily Evaluation Tool). 3. Select the proper device wh en requested by the application. 4. Plug the STEVAL-PCC009V2 demonstration board to a free USB port. 5. Wait a few seconds for board initialization. 6. Connect the SPI_IN connector (black) of the demonstration board to the 10-pin connector of the STEVAL-PCC009V2 board using the provided cable. For connecting more devices to the same board, please consult Section 6: Daisy chaining on page 29. 7. Power up the demonstration boards. The FLAG LED should turn on. 8. Click on the button with the USB symbol to connect the STEVAL-PCC009V2 board to the PC and initialize the evaluation environment. The application automatically identifies the number of demonstration boards connected. 9. The evaluation environment is ready. Before start working with the demonstration board, the device must be configured according to the indications described in Section 3: Device configuration. Warning: Important - the device configuration is mandatory. The default configuration is not operative.
Device configuration UM1685
3 Device configuration
This section offers an overview of the basic configuration steps which are required for make the demonstration board operative. More details about the configuration of the gate driving circuitry and the control algorithms are available in the AN4354 “L648x devices: gate drivers setup”. Warning: Important - the device configuration is mandatory. The default configuration is not operative. Important - before changing the device configuration verify that the device is in high impedance status (power stage is disabled).
3.1 Voltage mode driving (EVAL6480H)
The configuration parameters of the voltage mode driving can be obtained through the BEMF compensation tool embedded in the SPINFamily software. A wrong setup of these parameters could cause several issues, in particular: The phase current decreases with the speed and the motor will stall. The wrong voltage is applied to the motor and the system is very noisy. The phase current reaches the overcurrent limit. The BEMF compensation form uses the application parameters as inputs in order to evaluate the proper device setup. The required inputs are: Supply voltage. Target phase current (r.m.s. value) at different motion conditions (acceleration, deceleration, constant speed and holding). Target operating speed (maximum speed). Motor characteristics. The motor characteristics are: electrical constant (Ke), phase inductance and resistance. The inductance and the resistance of the phase are given in the motor datasheet. The Ke is rarely given in the specification and must be measured. In the help section of the SPINFamily software a step by step procedure is explained. The same procedure can also be found in the application note “AN4144: Voltage mode control operation and parameter optimization” on www.st.com. Click on the “evaluate” button to get the suggested setup for the voltage mode driving. Then click on “write” button to copy the data into the registers of the L6480 device.
UM1685 Device configuration
3.2 Advanced current control (EVAL6482H)
The following configuration gives good results with most of motors: Minimum ON time = 4 µs. Minimum OFF time = 21 µs. Max fast decay = 10 µs. Max fast decay at step change = 16 µs. Target switching time = 48 µs. Predictive current control enabled. The impact of the timing parameters are explained in the application note “AN4158: Peak current control with automatic decay adjustment and predictive current control: basics and setup” on www.st.com. The target phase current is set through the TVAL registers. The TVAL determinates the reference voltage (i.e. the voltage drop on the sense resistors) corresponding to the peak of the current sine wave (microstepping operation): Equation 1 I peak = TVAL_X / Rsense = TVAL_X / 0.05 The sensing resistors can be changed as described in Section 5: How to change the supply configuration of the board.
3.3 Gate drivers
The configuration of the gate driving circuitry depends on the external MOSFETs characteristics. The demonstration boards mount the STD25NF10 Power MOSFETs. Warning: Important - a wrong gate driving setup may cause spurious overcurrent failures even if no load is connected to the power stage. According to the STD25NF10 datasheet the total gate charge required to turn on the MOSFET is about 55 nC. The charge supplied by the device at each commutation is equal to the gate current (Igate) multiplied by the controlled current time (tcc). With a gate current of 64 mA and a controller current time of 1000 ns, 64 nC are provided to the gate. The gate current can be changed in order to speed up or slow down the commutation speed (i.e. the slew rate of the power stage outputs); in this case the controlled current time should be changed accordingly. The boards are designed to operate with a VCC voltage of 15 V, so the corresponding value for the integrated regulator should be set. The UVLO threshold should be 11 V. At each commutation some voltage oscillations are generated. This noise could trigger the overcurrent protection. This event is avoided by adding a blanking time after each commutation. A blanking time of 500 ns prevents the occurrence of spurious overcurrent detection in most operative conditions.
Device configuration UM1685 In conclusion the suggested configuration for the demonstration boards is following: VCC value = 15 V. UVLO threshold = 11 V (10 V on boot). Gate current = 64 mA. Controlled current time = 1 s. Dead time = 250 ns. Blanking time = 500 ns. Turn OFF boost time = disabled.
3.4 Overcurrent and sta ll detection thresholds
The overcurrent protection and the stall detection (EVAL6480H only) are implemented by measuring the drain-source voltage of the MOSFETs, hence their value is a voltage and not a current. The protection thresholds are set according to the voltage drop caused by the target triggering current on the MOSFET R dsON at the expected operating temperature (in fact this parameter increases with temperature). During the preliminary stages of evaluation, the max. value of 1000 mV can be set for both protections. The default value of 281.25 mV has a good probability to trigger the overcurrent alarm. Warning: Important - it is strongly discouraged to disable the overcurrent shutdown. It may result in critical failures.
3.5 Speed profile
The max. speed parameter is the maximum speed the motor will run. By default, it is about 1000 step/s. That means, if you send a command to run at 2000 step/s, the motor speed is limited at 1000 step/s. This is an important safety feature in the final application, but not necessarily useful to evaluate the device performances. Setting the parameter to high values (e.g. 6000 step/s) allows evaluating the maximum speed which can be achieved by the application under test through the speed tracking command (Run), but it probably limits the possibility to use positioning commands (Move, GoTo, etc.). The Full-step speed parameter indicates the speed at which the system switches from microstepping to full step operation. In voltage mode driving devices (EVAL6480H), it is always recommended to operate in microstepping and not to switch to the full step. Hence, this parameter should be greater than the maximum speed.
UM1685 Sensing resistors of the EVAL6482H
4 Sensing resistors of the EVAL6482H
The output current range of the board is determined by the sensing resistors as indicated in Equation 2 and Equation 3: Equation 2 Ipeak,min = 7.8 mV / Rsense Equation 3 Ipeak,max = 1 V / Rsense Where 7.8 mV and 1 V are the minimum and the maximum value of the TVAL registers. However the actual output current is usually limited by the power rating of the sensing resistors: Equation 4 Note: The power rating of the sensing resistor de termining the maximum output current is 50% of the nominal one. If the operative range resulting from the sensing resistors which are mounted on the board is not suitable for the application, it is possible to change these components in order to fit the requirements. The sensing resistors should make the current control to operate with a peak reference voltage between 0.2 and 0.1 volts. This way the power dissipation on the sensing resistor is not excessive and the offset of the sensing circuitry does not affect the performance of the current control algorithm. Equation 5 R sense = 0.2 V / Ipeak Iout limit Pdm a x Rsense
5 How to change the supply configuration of the board
as listed in Table 11, Table 12 and Table 13. be lower than the respective UVLO threshold and the device is not operative. this event (the diodes of the charge pump must also be low drop type). internal ESD diode is turned on and the device could be damaged. Table 11. VCC supply configurations (see following text below table). (see following text below table). Table 12. VREG supply configurations (see following text below table). (see following text below table).
6 Daisy chaining
More demonstration boards can be connected in daisy chain mode.
- Connect the STEVAL-PCC009V2 board 10-pi n connector to the SPI_IN connector of
the first demonstration board through the 10-pole flat cable.
- Open the termination jumper (see Section 1.1: EVAL6480H on page 5 and Section 1.2:
- Connect the SPI_OUT connector of the firs t demonstration board to the SPI_IN of the
next one through the 10-pole flat cable.
- Repeat point 2 and 3 for all the other s board of the chain but the last one.
- Check the termination jumpers of the demons tration boards: all the jumpers but the last
performances. If communication issues occur, try to reduce the SPI clock speed. Table 13. VDD supply configurations Supplied by VREG Closed Open 3.3 V Default, 3.3 V logic.
7 Revision history
Table 14. Document revision history 28-Nov-2013 1 Initial release. “cSPIN™” and “cSPIN™ family” by “L648x”). on page 13 (converted to greyscale). Minor modifications throughout document.