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Datasheet

Datasheet

BM6204FS

TSZ02201-0828AB400120-1-2

© 2014 ROHM Co., Ltd. All rights reserved.

09.Sep.2015 Rev.002

http://www.rohm.com

TSZ22111 · 15 · 001

Description of Blocks

1. Commutation Logic

When the hall frequency is about 1.4-Hz or less (e.g. when the motor starts up), or PC pin is “L”, the commutation mode

is 120° square wave drive with upper and lower switching (synchronous switching). The controller monitors the hall

frequency, and switches to upper switching when the hall frequency reaches or exceeds about 1.4-Hz over four

consecutive cycles and PC pin is “H”. Refer to the timing charts in figures 12 and 13.

2. Duty Control

synchronous switching). The VSP pin is pulled down internally by a 200 kΩ resistor. Therefore, note the impedance when

setting the VSP voltage with a resistance voltage divider.

3. Carrier Frequency Setting

The carrier frequency setting can be freely adjusted by connecting an external

resistor between the RT pin and ground. The RT pin is biased to a constant

voltage, which determines the charge current to the internal capacitor. Carrier

frequencies can be set within a range from about 16 kHz to 50 kHz. Refer to the

formula to the right.

4. FG Signal Output

The number of FG output pulses can be switched in accordance with the number

of poles and the rotational speed of the motor. The FG signal is output from the FG

pin. The 12-pulse signal is generated from the three hall signals (exclusive NOR),

and the 4-pulse signal is the same as hall U signal. It is recommended to pull up

FGS pin to VREG voltage when malfunctioning because of the noise.

5. Direction of Motor Rotation Setting

The direction of rotation can be switched by the CCW pin. When CCW pin is “H” or

open, the motor rotates at CCW direction. It is recommended to pull up CCW pin to

VREG voltage when malfunctioning because of the noise.

6. Hall Signal Comparator

The hall comparator provides voltage hysteresis to prevent noise malfunctions. The bias current to the hall elements

We recommend connecting a ceramic capacitor with value from 100 pF to 0.01 µF, between the differential input pins of

the hall comparator. Note that the bias to hall elements must be set within the common mode input voltage range

Table 1. 120° commutation (synchronous switching) truth table

HU

HV

HW

UH

VH

WH

UL

VL

WL

H

L

H

L

PWM

L

H

PWM

--------------------

L

H

L

L

L

L

PWM

H

L

PWM

--------------------

H

H

L

L

L

PWM

L

H

PWM

--------------------

L

H

L

PWM

L

L

PWM

--------------------

H

L

L

H

H

PWM

L

L

PWM

--------------------

L

H

L

L

H

L

PWM

L

L

PWM

--------------------

H

FGS

No. of pulse

H

12

L

4

CCW

Direction

H

CCW

L

CW

]

kohm

[

R

400

]

kHz

[

f

T

OSC

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