Advertisement
7.4. High-side current monitor: OCM pin
The current which flows to high side Tr (Pch) in H-bridge of motor-driven output (0A-6A) is monitored
in real time. Then a current value of 0.223% (0 to 13.38mA) of its current value is output in aOCM pin.
The current can be monitored by inserting an external resistance (220Ω*1) between OCM pin and GND.
Additionally this voltage is input to MCU, and the motor state (such as motor lock, the load OPEN
when operating, and angle detection of a throttle) can be monitored.
Current
monitor
OUT1
Figure 7.4-1 Block diagram of high-side current monitoring
Note: Some of the functional blocks or circuits in the block diagram may be omitted or simplified for
explanatory purposes.
* This resistance (220Ω*1) assumes in the case that the power supply of MCU (ADC) is 5V.
When the power supply of MCU is less than 5V, use adjusting of ressistance value.
Be careful for the external resistance (220Ω). Sufficient evaluation is required since not only the
resistance value fluctuates but also the output voltage also fluctuates.
* The external capacitor (*2) should select whether it connects according to the purpose of system use.
For example, the operation in the case of flowing a current of 3A is as follows. However, repeating from
forward to reverse is inhibited, and it assumes that the short brake is inserted between them and
operated .
Figure 7.4-2 Timing chart of high-side current monitoring
VBAT
Current
monitor
monitoring circuit
OUT2
GND
16 / 49
In the case of 3A
6.7mA(typ)＊220Ω＝1.47V
In the case of 6A
13.38mA(typ)*220Ω=2.94V
OCM
Current
TB9051FTG
Monitoring in
MCU
1μF
２2０Ω
(*1)
(*2)
Ver.1.1 2019-03-14
Advertisement
