AMIS-30522(2009) 데이터 시트보기 (PDF) - ON Semiconductor

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AMIS-30522
(Rev.:2009)

Micro-Stepping Motor Driver

ON Semiconductor 

Ssh

VCOIL

div2

div4

AMIS−30522, NCV70522

Sh

Csh

buf

Ch

SLA−Pin

Icoil=0

PWMsh

PWMsh

Icoil=0

SLAT

VCOIL

SLAT

NOT (Icoil=0)

t

SLA−Pin

last

sample

is

retained

VBEMF

previous output is

kept at SLA pin

retain last sample

t

SLAT = 1 => SLA−pin is “transparent” during

VBEMF sampling @ Coil Current Zero

Crossing. SLA−pin is updated “real−time”.

SLAT = 0 => SLA−pin is not “transparent”

during VBEMF sampling @ Coil Current Zero

Crossing. SLA−pin is updated when leaving

current−less state.

Figure 14. Timing Diagram of SLA−Pin

Warning, Error Detection and Diagnostics Feedback

Thermal Warning and Shutdown

When Junction temperature rises above TTW, the thermal

warning bit <TW> is set (Table 16 SPI Status Register 0). If

junction temperature increases above thermal shutdown

level, then the circuit goes in “Thermal Shutdown” mode

(<TSD>) and all driver transistors are disabled (high

impedance) (Table 16 SPI Status Register 2). The conditions

to reset flag <TSD> is to be at a temperature lower than TTW

and to clear the <TSD> flag by reading it using any SPI read

command.

Overcurrent Detection

The overcurrent detection circuit monitors the load

current in each activated output stage. If the load current

exceeds the overcurrent detection threshold, then the

overcurrent flag is set and the drivers are switched off to

reduce the power dissipation and to protect the integrated

circuit. Each driver transistor has an individual detection bit

in the Table 16 SPI Status Registers 1 and SPI Status

Register 2 (<OVCXij> and <OVCYij>). Error condition is

latched and the microcontroller needs to clear the status bits

to reactivate the drivers.

Note: Successive reading the SPI Status Registers 1 and 2 in

case of a short circuit condition, may lead to damage to the

drivers.

Open Coil Detection

Open coil detection is based on the observation of 100%

duty cycle of the PWM regulator. If in a coil 100% duty cycle

is detected for longer than 32 ms the appropriate status bit in

the SPI status register is set (<OPENX> or <OPENY>).

(Table 16: SPI Status Register 0).

When the resistance of a motor coil is very large and the

battery voltage is low, it can happen that the motor driver is

not able to deliver the requested current to the motor. Under

these conditions the PWM controller duty cycle will be

100% and after 32 ms, the error pin and <OPENX>,

<OPENY> will flag this situation (motor current is kept

alive). This feature can be used to test if the operating

conditions (supply voltage, motor coil resistance) still allow

reaching the requested coil−current or else the coil−current

should be reduced.

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