LB11824M Просмотр технического описания (PDF) - SANYO -> Panasonic

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LB11824M

Direct PWM Drive Brushless Motor Predriver for On-Demand Water Heater and Air Conditioner Motors

SANYO -> Panasonic 

LB11824M

9. Motor lock protection circuit

A motor lock protection circuit is incorporated for protection of IC and motor when the motor is locked. When the

Hall input signal is not changed for a certain period with the motor driving, the one-side output (UH, VH, WH) is

turned OFF. The time is set by means of a capacity of a capacitor connected to the CSD pin.

Set time (s) .=. 154 × C (µF)

Addition of a 0.01 µF capacitor causes a protection time of about 1.54 seconds. (Drive is turned OFF when one cycle

of Hall input signal is longer than this time period.) The time to be set must have a sufficient allowance so that the

protection is not activated at a normal motor startup. Select the capacitor of 4700 pF or more. The protection circuit is

not activated when braking. To cancel the restriction protection condition, one of following steps must be taken:

• Stop mode (10 µs or more)

• Maintaining the output duty 0% condition through input of VCTL or PWMIN for more than the period of tCSD × 2.

(tCSD (s) .=. 0.5 × C (µF). When the 0.01 µF capacitor is added, maintaining for about 10 ms or more is necessary.)

• Re-application of power supply

The CSD pin acts also as an initial reset pulse generation pin and causes reset of the logic circuit when connected with

GND. Accordingly, the motor drive condition can not be obtained. When this pin is not to be used, a resistor of about

150 kΩ and a capacitor of about 4700 pF must be connected to GND in parallel. When the restriction protection circuit

is not used, following functions are also invalid:

• Protection circuit for the reverse mode

• Overheat protection circuit

10. Overheat protection circuit

One-side output (UH, VH,WH) is turned OFF when the junction temperature (Tj) exceeds a specified temperature

(TSD). Since the minimum variation of TSD is 125°C, thermal design must be made so that Tj = 125°C is not

exceeded except in the case of abnormality. Accordingly, Pdmax when Tj (max) = 125°C is 0.72 W (Ta=25°C)

When the motor lock protection is not to be used by inserting in parallel the resistor of about 150kΩ and capacitor of

about 4700pF between the CSD pin and GND, this overheat protection circuit does not function.

In this case, Tj (max) = 150°C, so that Pdmax = 0.9W (Ta = 25°C)

11. Forward/reverse rotation

To select forward or reverse in the rotation condition, a measure is taken to prevent flow of the through current

(through current due to the output Tr OFF delay time at selection) at the output. Selection during rotation causes the

current exceeding the current limit value to flow through the output Tr because of the motor coil resistance and motor

reverse electromotive voltage condition. It is therefore necessary to select the external output Tr that is not damaged by

this current or to select forward/reverse only when the motor rotation speed has decreased to a certain level.

12. Power supply stabilization

This IC is of a switching drive type and the power line tends to be affected. It is therefore necessary to connect a

capacitor of sufficient capacity for stabilization between the VCC1 pin and GND.

To insert a diode in the power line to prevent breakdown through reverse connection of power supply, the power line

becomes more readily affected. It is necessary to select a larger capacity.

To turn ON/OFF the power supply with a switch, etc., large distance between the switch and capacitor causes

substantial deviation of the supply voltage due to the line inductance and inrush current into the capacitor. In certain

cases, the withstand voltage may be exceeded. In this case, do not use a ceramic capacitor whose series impedance is

low. Instead, use an electrolytic capacitor to suppress the inrush current and to prevent voltage rise.

13. VREG stabilization

To stabilize the VREG voltage that is the power supply for the control circuit, connect a 0.1µF or more capacitor

between VREG and GND. The capacitor GND must be wired near the GND pin of IC as much as possible.

No. 7107-16/17

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