feature

Common built-in thermal shutdown circuit (TSD) 8 independent voltage sources

Corresponds to 3.3V or 5V digital signal processor

4 optional silent input spindles

Output PWM Mode Control

FG output: Open collector type

Optional braking (short braking and reverse braking) built-in Hall bias 180o commutation (compatible with traditional brushless DC spindle motors)

Built-in short-circuit protection function BTL (base 2 channels) Output PWM mode control Built-in short-circuit protection function BTL (other 4 channels)

Output Linear Mode Control

typical application

CD-ROM, CD-RW, DVD-ROM, DVD-RAM, DVD player (DVDP), other CD-ROM media, game consoles

illustrate

Suitable for three-phase brushless DC spindle motor driver with PWM, monolithic FAN8741/FAN8742 IC including 2-channel motor driver with pedestal motor and 4-channel motor with pulse width modulation to drive focus actuator, tracking actuator, tilt linear Drivers and loading motors in optical media applications. Specifically designed for high speed/high density optical media applications, the power stage of the FAN8741/FAN8742 consists of D-MOS transistors with very low RDSON. This reduces heat generation and ensures increased reliability. The FAN8741G/FAN8742G are packaged in a 56-SSOP-HS package with high power dissipation and the lead frame is exposed on the top. The FAN8741MTF/FAN8742MTF is available in 56-TSSOP-EP in a very thin package with the lead frame exposed on the bottom.

Internal block diagram (pins numbered by FAN8741MTF - bottom lead frame exposed)

1.56-TSSOP-EP, Case 1: Single-layer PCB, only 1 signal plane, PCB size is 76mm×114mm×1.6mm.

2.56-TSSOP-EP, Case 2: Multilayer PCB with 1 Signal, 1 Power, and 1 Ground Plane, PCB Dimensions 76mm x 114mm x 1.6mm, Copper Power, Ground Plane Dimensions 74mm x 62mm ×0.035mm. The lower pads of the integrated circuit are soldered on the printed circuit board.

3.56-TSSOP-EP, Case 3: The PCB conditions are the same as Case 2, except for vias that penetrate all layers of the PCB. The bottom pad of the integrated circuit is soldered on the printed circuit board.

4.56-SSOP-HS, Case 1: Single-layer PCB, only 1 signal plane, PCB size is 76mm×114mm×1.6mm.

5.56-SSOP-HS, Case 2: Multilayer PCB with 1 Signal, 1 Power, and 1 Ground Plane, PCB Dimensions 76mm x 114mm x 1.6mm, Copper Power, Ground Plane Dimensions 74mm x 62mm ×0.035mm.

6. In 56-TSSOP-EP case 1, using a temperature higher than Ta=25°C, the power consumption is reduced by -12.8mW/°C.

7. In 56-TSSOP-EP case 2, using a temperature higher than Ta=25°C, the power consumption is reduced by -25.6mW/°C.

8. In case 3 of 56-TSSOP-EP, if a temperature higher than Ta=25°C is used, the power dissipation will be reduced by -32.8mW/°C.

9. Using a temperature higher than Ta=25°C in case 1 of 56-SSOP-HS, the power consumption is reduced by -24.8mW/°C.

10. In 56-SSOP-HS case 2, using a temperature higher than Ta=25°C reduces power dissipation by -37.6mW/°C.

11. Do not exceed PD and SOA (Safe Operating Area).

Electrical Characteristics (Ta=25°c)

(Ta=25°C, SVCC1=VDD=PVCC1=VM2=5V, VM1=SVCC2=PVCC2=PVCC3=12V, unless otherwise stated)

Electrical Characteristics (Ta=25°C, continued)

(Ta=25°C, SVCC1=VDD=PVCC1=VM2=5V, VM1=SVCC2=PVCC2=PVCC3=12V, unless otherwise stated)

application information

1. Torque control and output current control of three-phase brushless DC motor

1) By amplifying the voltage difference between VREF and spin of the servo IC (or digital signal processor), the torque amplifier generates an input voltage (VAMP), which represents the input current command.

2) The output current (IO) is converted into a voltage (VCS) through a sense resistor (RCS) and compared with VAMP.

3) The clock generator always makes the RS latch set periodically, which makes it turn off when the VCS while the uppers are equal.

4) Through the negative feedback loop, the detected output voltage VCS is equal to VAMP.

5) The commutation sequence is selected by the Hall sensor input, and the minimum Hall input is 50mV.

6) The calculation of gain and limit current is shown in the table below. (Gvo=VAMP/(SPIN-VREF)=1[V/V]).

7) The spindle seat adopts 180o commutation method, which is fully compatible with the traditional brushless DC spindle motor. Users do not need to change or modify their spindle motors.

8) When Rcs=0.33Ω, REXT1=0, the range of input voltage is as follows.

2. Torque control and output current control of trolley motor (two-phase stepper motor)

1) By amplifying the voltage difference between VREF and SLIN1 (or SLIN2) of the servo IC (or DSP), the torque amplifier generates an input voltage (VAMP), which represents the input current command.

2) The output current (IO) is converted into a voltage (VCS) through a sense resistor (RCS) and compared with VAMP.

3) The clock generator always makes the RS latch set periodically, which makes it turn off when the VCS while the uppers are equal.

4) Through the negative feedback loop, the detected output voltage VCS is equal to VAMP.

5) In order to avoid the short circuit of the upper and lower transistors of the output, a switching skill is required. The turn-on delay is 1 second, so when changing the current direction, the delay is 1 second.

6) The calculation of gain and limit current is shown in the table below. (Gvo=VAMP/[SLIN1 (or SLIN2)-VREF]=1[V/V]

3. Schematic diagram of channel 1~4

The reference voltage (ref) is provided externally through pin21.

The input op amp output signal is amplified (20K/10K) times, and then fed into the power amplifier. The gain of the power amplifier is so the maximum total gain for channels 1 to 4 is 8.

4. Mute input FAN8741 has two independent mute pins: pin 22 (mute 1) and pin 23 (mute 2). Details such as

Note:

In order to make the spindle short brake, MUTE2 becomes low, and the spindle command cannot be in the dead zone (±50mV). When the spindle command is in the deadband, the spindle block goes into disable mode even if MUTE2 is low.