Features

Single H Bridge PWM motor drive

- Single -brush DC motor drive

--1/2 Dual -step motor drive

5-a peak or 3.5-a RMS output current

6.5-45-V working power supply voltage range

simple pH; /EN control interface

multiple decay modes

- Mixed decay

- Slow decay

- Fast attenuation

] Low -current sleep mode (10μA)

small packaging and area

–28 HTSSOP (power board)

#8226 ; Protection function

-vm IOU Lock (UVLO)

- Over -current protection (OCP)

- Hot shutdown (TSD)

- Failure Status indicator pin (nfault)

Application

Automatic withdrawal machine and currency processor

Camera

# 8226; multi -functional printer and scanner

Office automation machine

Game machine

Factory automation and robotics [123 123 [123 ]

stage lighting equipment

Instructions

DRV8829

is an industrial application of a DC motor or 1/2 dual -pole step -drive driver. The device output level consists of an N -channel power MOSFET H bridge drive. DRV8829 can drive up to 5 A peak current or 3.5 A RMS current (with an appropriate printing circuit board ground floor, for heat dissipation, under 24 V and TA 25 ° C).

PH/EN pin provides a simple control interface. An internal inductive amplifier allows adjustable current control. Using a dedicated NSLEEP pin provides a low -power dormant mode for a very low static current standby. The current adjustment attenuation mode can be set to slow attenuation, fast attenuation or mixed attenuation.

Provide internal protection functions of under pressure, overcurrent, short circuit and overheating. The failure state is instructed by the NFAULT pin.

Equipment information

(1), please refer to the appointment appendix at the end of the data table.

Simplified schematic diagram

Typical features

Detailed description

Overview [overview [overview

Overview [overview

Overview [overview

Overview [overview

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DRV8829 is an integrated motor solution for bipolar step motors or single/dual -brushing DC motors. This device integrates the NMOS H bridge and current adjustment circuit. DRV8829 can use the power supply voltage of 8.2 to 45 V, and can provide an output current up to 5 A peak or 3.5 A RMS. The actual capacity of the operation is based on the size of the ambient temperature, the power supply voltage and the PCP ground floor size.

A simple PH/EN interface can easily connect to the controller circuit.

The current adjustment is highly configured and has a variety of attenuation modes. The attenuation mode can be selected as a fixed slow, mixed, or rapid attenuation.

The current characteristics of the current allow the controller to zoom output current without the need to zoom analog reference voltage input VREF. Use a digital input pin to access DAC. This allows the controller to save electricity by reducing the current consumption.

Including a low -power dormant mode, the system allows the system to save electricity when not driving the motor.

Function box diagram

Feature description

PWM motor driver

DRV8829 contains an current control PWM circuit H Bridge motor driver. Figure 3 shows the frame diagram of the motor control circuit. Double -step motor is displayed, but the driver can also drive DC motors.

There are multiple VM, Isen, OUT and VREF pin. All naming pipes must be connected together on PCB.

Sweeding time

After the current is enabled in the H bridge, the voltage on the Isen pin will be ignored before the current detection circuit is enabled. The hidden time is fixed to 3.75μs. The hidden time also sets up the minimum connection time of pulse width modulation.

reset and NSLEEP operation

When the low level is driven, the NRESET pin reset internal logic. It also disables the H bridge driver. When NRESET is active, all inputs will be ignored.

Low NSLEEP will enable the device to enter a low -power sleep state. In this state, the H bridge is disabled, the gate driver's charge pump stops, the V3P3OUT regulator is disabled, and all internal clock stops. All inputs in the Leensp state will be ignored until the high level is returned. When returning from the sleep mode, the motor drive can be fully worked after a period of time (about 1 millisecond). nresetThe internal drop -down resistance of NSLEEP is about 100 kΩ. These signals need to be driven to logic high levels for device operations.

Protective circuit

DRV8829 has sufficient protection to prevent pressure, over current and overheating events.

Overcurrent protection (OCP)

The analog current limit circuit on each FET is limited to the current by removing the grid driver. If the simulation current limits the duration of the OCP time, all FETs in the H bridge will be disabled, and the NFAULT pin will be driven to a low level. The device will remain disabled until NRESET PIN is applied, or VM is removed and re -applied.

Over -current conditions on high -voltage and low -voltage side devices; that is, short -circuit, short -circuit of power supply, or short circuit of motor winding, will lead to over -current stop. Overcurrent protection is not used in the current detection circuit for PWM current control, and has nothing to do with Isense resistance or VREF voltage.

Hot shutdown (TSD)

If the mold temperature exceeds the safety limit, all FETs in the H bridge will be disabled, and the NFAULT pin will be driven to a low level. Once the mold temperature drops to the safe level, the operation will automatically restore.

IOU locking (UVLO)

If the voltage on the VM pins is lower than the voltage of the underwriting lock at any time, all circuits in the device will be disabled, the internal logic will be heavy, and the internal logic will be heavy. Set. When VM is higher than the UVLO threshold, the operation will be restored.

current adjustment

The current of the motor winding is adjusted by a fixed frequency PWM current adjustment or current cut wave wave. When the H bridge is enabled, the current passes through the winding to rises on the velocity of the DC voltage and inductance of the winding. Once the current reaches the current chopping threshold, the bridge will disable the current until the next PWM cycle starts.

For step motor, current adjustment is usually used, which can be used to enter the micro -step motor by changing the current. For DC motors, the current adjustment is used to limit the starting and stall current of the motor.

If the current adjustment function is not required, it can be disabled by connecting the Isense pin directly to the ground and connecting the VREF pin to V3P3.

The PWM cut wave current in each bridge is set by the comparator. The comparator will be compared by the voltage of the current detection resistor that is connected to the Isen pin. The reference voltage is input from the XVREF pin and a zoom of 5 digits of DAC. The DAC allows 0 to 100%current settings in the approximate sine sequence.

Full marking (100%) cut wave current is calculated in Formula 1.

Example: If you use 0.25- sensory electricityThe resistor and the VREFX pin are 2.5 V, and the full marker (100%) cut current will be 2.5 V/(5 × 0.25 ) 2 a.

Five input pins (I0-I4) are used to shrink the current in the bridge into a percentage of the full volume current set by VREF input pins and sensing resistance settings. The internal drop-down resistance of the i0-I4 pins is about 100 kΩ. The function of sales is shown in Table 1.

Equipment function mode

Bridge control

phase input pins control flowing across the H bridge H bridge The current direction. ENBL input pin usually enables H bridge output when activating high electricity. Table 2 shows logic.

Control the input of internal pull -off resistors with about 100 kΩ.

Dechatal mode

During the PWM current chopping process, the H bridge can drive the current through the motor winding until the PWM current chopping threshold is reached. This shows case 1 in Figure 4. The displayed current direction indicates the state of the phase pins.

Once the cutting current threshold is reached, the H bridge can work in two different states, fast attenuation or slow attenuation.

In the fast attenuation mode, once the PWM cutting current level is reached, the H bridge will reverse to allow the winding current reverse flow. When the winding current is close to zero, the bridge is banned to prevent any reverse current flow. The fast attenuation mode is shown in Figure 4 as the case 2.

Under the mode of slow attenuation, the winding current through two low -side FETs in the bridge is re -circulated. This is shown in Figure 4 as Case 3.

DRV8829 supports fast attenuation, slow attenuation and mixed attenuation mode. Slow, fast, or mixed decaying mode is selected from the state of the decaying tube-logic low selection slow decay, open the selection of hybrid decaying operations, and set the rapid decay mode. The internal pull -up resistance of the decaying tube is about 130 kΩ, and the internal pull -down resistance is about 80 kΩ. If the pin is kept or unavailable, a mixed attenuation mode is set.

The mixed attenuation mode starts with rapid attenuation, but switches to the slow attenuation mode in a fixed period (75%of the PWM cycle) to switch to the slow attenuation mode within the remaining time of the fixed PWM cycle.

Application and implementation

Note

The information in the following application chapters is not part of the TI component specification, TI does not guarantee its accuracy or integrity. TI's customers are responsible for determining the applicability of the component. Customers should verify and test their design implementation to confirm the system function.

Application information

DRV8829 is used for bristles or stepsEnter the motor control.

Typical application

In this application, DRV8829 will be used to drive a DC motor. The following design process can be used to configure DRV8829.

Design requirements

Table 3 gives system design design input parameters.

Detailed design program

Maximum current (ITRIP) is set by IX pin, VREF analog voltage and sensor resistance (RSENSE). When starting with a DC motor, there may be a large excitation surge because there is no anti -electrocomotive momentum. Start current limits to prevent the current from being excessive.

Example: If the required chop current is 3.5 a, set RSENSE 100 M , VREF must be 1.75 volts.

Create a resistor separator from V3P3OOT (3.3 V) to set VREF≈1.75 V.

Set R2 18 k , set R1 16 k .

sensing resistor

In order to obtain the best performance, the sensor must be:

Low inductance

The rated power is high enough

near the motor drive

The power consumption of sensor resistance is equal to IRMS2X R. For example, if the RMS motor current is 2-a and 100-M the sensor, the resistor will consume 2 A2 × 0.1 0.4 W. As the current level increases, power increases rapidly.

The resistor usually has a rated power within certain ambient temperature range, and the reduction of power curve at high ambient temperature. When a PCB is shared with other heating elements, the balance should be increased. It is best to measure the actual sensing resistance temperature and power MOSFET in the final system, because they are usually the hottest components.

Since the power resistor is larger and more expensive than the standard resistor, multiple standard resistors are usually used between sensing nodes and grounding. This can allocate current and heat dissipation.

Application curve

Power suggestion

DRV8829 is designed for input voltage power supply (VM) of 8.2 V to 45 V. Work. The absolute maximum rated value of the device is 47 V. 0.1-μF ceramic capacitors with the rated value must be placed on eachOn the VM pin, as close to DRV8829 as much as possible. In addition, VM must include a large capacitor.

Overall capacitance size

It is an important factor in the design of the motor drive system. Generally speaking, more volume capacitors are beneficial, but the disadvantage is increased cost and physical dimensions.

The required local power capacity depends on multiple factors, including:

the highest current required for the motor system.

capacitance and ability to provide current.

Parasitic inductance between the power supply and the motor system.

acceptable voltage ripples.

the type of motor (brush, brushless DC, step motor).

motor braking method.

The inductance between the power supply and the motor drive system will limit the change rate of power current. If the local large -capacity capacitance is too small, the system will respond to excessive current requirements, or uninstall from the motor as the voltage changes. When using sufficient large -capacity capacitors, the motor voltage remains stable and can quickly provide large current.

The data table usually provides a recommended value, but it is necessary to perform system -level tests to determine large -capacity capacitors with appropriate size.

The rated voltage of a large capacitor should be greater than the operating voltage in order to provide the maneuverability when the motor transmits energy to the power supply.

Layout

Layout Guide

Each VM terminal must use low ESR ceramic road capacitors bypass to GND, the recommended value is to be, the recommended value is to be, the recommended value is to be, the recommended value is to be, and the recommended value is to be. VM rated value is 0.1 μF. These capacitors should be placed near the VM pin as much as possible, and have a thick trace line or ground plane connection with the GND pins of the device.

VM pins must use large -capacity capacitors rated as VM to bypass the ground. This ingredient may be an electrolyte.

Low ESR ceramic capacitors must be placed between CP1 and CP2 pin. TI recommends VM's rated value of 0.1 μF. Try this part as close as possible.

Low ESR ceramic capacitors must be placed between VM and VCP pins. TI's recommended 16 V rated value is 0.47 μF. Try this part as close as possible. In addition, 1 MΩ is placed between VM and VCP.

Use a ceramic capacitor with a rated voltage of 6.3 V to bypass V3P3 to ground. The bypass capacitor is as close to the pin as much as possible.

The current detecting the resistor should be as close to the device pin as much as possible to minimize the traces of the traces between the pin and the resistor.

layout example

Heat Precautions

DRV8829 has the heat shutdown (TSD) as described above. If the mold temperature exceeds about 150 ° C, the device will be disabled until the temperature drops to the safe level.

Any trend of the device entering TSD indicates that the power consumption is too large, insufficient heat dissipation, or the environmental temperature is too high.

Power consumption

The power consumption in DRV8829 is mainly controlled by the output FET resistance or the power consumption consumed in RDS (on).

The average power consumption of the stepping motor may be roughly estimated by Formula 3.

Among them

ptot is total power consumption

rds (on) is each fet of each fet Resistance (high -voltage side and low voltage side)

IOUT (RMS) is the RMS output current that is applied to each winding (3)

iOut (RMS) is about the full marking degree 0.7 times the output current settings.

The maximum power consumed in the device depends on the ambient temperature and heat dissipation.

RDS (on) increases with the increase of temperature, so the power consumption increases with the heating of the device. When determining the size of the heat sink, this must be considered.

Heating

Power board #8482; Packaging uses an exposed cushion to remove the heat of the device. In order to correctly operate, the pad must be connected to the copper heat on the PCB to dissipate heat. On the multi -layer PCB with the floor, this can be achieved by adding multiple holes to connect the hot pad to the horizon. On PCB without internal planes, you can add copper area to any side of the PCB to dissipate heat. If the copper zone is on the other side of the PCB, the thermal hole is used to convey the heat between the top and the bottom layer.

Generally speaking, the more copper area provided, the greater the consumption power.