tb62300fg TOSHIBA Semiconductor CORPORATION, tb62300fg Datasheet - Page 10

• Manufacturer Part Number: tb62300fg
• Description: Dual Full-bridge Driver For Dc Motor
• Manufacturer: TOSHIBA Semiconductor CORPORATION

PWM Operation
Notes: ･f
Description
The output H bridge is driven by an external PHASE signal.
It, however, also uses the fcr signal, generated with external CR, to generate blanking time and Mixed Decay time. The above logic is configured to handle the two
signals, PHASE and fcr, which are asynchronous to each other. The logic generates internal reset signal edges from external PHASE edges, resulting in the width
equal to two fcr cycles.
The fcr-based counter assumes the first fcr falling edge following the PHASE edge as the first count. The maximum phase difference between the PHASE and fcr
signals is, therefore, one fcr cycle.
The serial blanking time starts at the second count based on the fcr clock (The first three samples of serial blanking time signal must be 000).
The last stage output is switched by the edge of the external PHASE signal. That means there is an interval of two fcr cycles before the set blanking time starts.
To cover the interval, the logic generates the time between the PHASE signal edge and blanking time start as phase blank time, during which comparison is masked
off in the same way as in blanking time.
Consequently, the blanking time as viewed from outside the IC is within the range from one fcr cycle (TBlank (000)) to eight fcr cycles (TBlank (111)) + I phase
difference between PHASE and fcr (up to two fcr cycles).
f
PHASE
Internal reset signal
Phase Blank Time
Serial Blanking Time
Total Blanking Time
Output control signal
CR
･PHASE is an external signal.
･The internal reset signal resets the internal clocks and counters.
･Phase Blank Time is time between either edge of the external PHASE signal and the leading edge of serial blanking time.
cr
(f
is 16 times the f
chop
* 16)
chop
frequency.
Example:
1/fcr * 2
Example: 1/fcr * 2 + 1/fcr * TBlank
1
1/fcr * 2
Input range for fcr clock
2
1/fcr * TBlank
3
4
5
6
･････
10
TB62300FG
2005-04-04