STK6877 데이터 시트보기 (PDF) - SANYO -> Panasonic

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STK6877

Reversible Brush-Type DC Motor Driver (output current: 8 A)

SANYO -> Panasonic 

Usage Notes

1. Drive Circuit Start-up Procedure

STK6877

Figure 7 Upper and Lower MOSFET Drive Circuits

When starting (applying power to) the driver circuit (STK6877), the external control signals must be set to standby

mode, i.e., pins A and B both set to low (setting both these pins high is an illegal mode). Then, after the specified power

supply voltages (VCC1 and VCC2) have been input to the driver circuit, the circuit can be driven by inputting external

control signals.

2. Illegal Input Mode with both the A and B Phase Signals (pins 13 and 15) High

Since the circuit operation problems described below occur when the input signal mode with both signals high is used,

this mode should be avoided.

2-1 If used in the standby state, the voltage (Vch) charged on the external bootstrap capacitor (47 µF/16 V) will drop to

an inadequate level. As a result, when the STK6877 driver circuit is switched to the start-up state, an insufficient

drive voltage state for the upper FETs (F1 and F2) will occur.

2-2 If the A and B phase input signals are both switched to the high level in the motor start-up state (CW or CCW

mode), a current loop (braking current) will be created in the upper side FETs due to the motor energy. At this

point, since the upper FET drive voltage (the VGS voltage) drops, an insufficient drive state will occur in the upper

FETs, and they may be destroyed. However, if during this operation the charge voltages Vch across the two

terminals of the bootstrap capacitors (47 µF/16 V) are monitored at the following points:

x

y

The voltage between pin 10 and pin 8 (or 9) ......................................Phase A...................(1)

The voltage between pin 1 and pin 4 (or 5) ........................................Phase B

and if both these voltages can be maintained at 4.0 V or higher, then the A and B phase pin input signals can both

set to high safely. In other words, if the A and B phase pin input signal mode with both signals high is used as a

motor stopping technique, care must be taken to assure that the charge voltages Vch on the external bootstrap

capacitors meet this condition.

3. Handling the Hybrid IC’s PG (pins 2 and 3) and SG Pins (pin 12)

Basically, the PCB pattern must be designed so that the PG and SG pins connect to a single grounding point. Also, if a

current detection resistor (RE) is inserted on the PG pin, handle the PG and SG pins as shown in Figure 8, i.e., connect

them to a single grounding point, and select a value of the resistor RE so that the voltage drop VRE meets the following

condition.

VRE = (IOH × RE) ≤ 0.5 V ...................................................(2)

IOH: Motor output current (A)

RE: Current detection resistance(Ω)

VRE: Voltage drop across RE (V)

The condition specified by formula (2) is specified in the

specifications as the sensing voltage Vsens.

Figure 8 Handling for the PG and SG Pins

No. 4874-5/8

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