STK672-340-E

No.A1254-6/13

[CLOCK (Phase switching clock)]

• Input frequency: DC to 50kHz

• Minimum pulse width: 10μs

• Signals are read on the rising edge.

[CWB (Motor direction setting)]

The direction of rotation is switched by setting CWB to 1 (high) or 0 (low). See the timing charts for details on the

operation of the outputs.

Note: The state of the CWB input must not be changed during the 6.25

μs period before and after the rising edge of

the CLOCK input.

[ENABLE (Forcible on/off control of the A, AB, B, and BB outputs, and selection of the operate or hold state for

hybrid IC internal operation)]

ENABLE = 1 (high): Normal operation

ENABLE = 0 (low): Outputs A, AB, B, and BB forced to the off state.

If, during the state where CLOCK signal input is provided, the ENABLE pin is set to 0 (low) and then is later

restored to the 1 (high) state, the IC will resume operation with the excitation timing continued from before the point

ENABLE was set to 0 (low).

[MODE (Excitation mode selection)]

MODE = 0 (low): 2-phase excitation

MODE = 1 (high): 1-2 phase excitation

See the timing charts for details on output operation in these modes.

Note: The state of the MODE input must not be changed during the 5

μs period before and after the rising edge of the

CLOCK input.

2. Allowable motor current operating range

The motor current (IOH) must be held within the range corresponding to the area under the curve shown in figure 3.

For example, if the operating substrate temperature Tc is 105°C, then IOH must be held under IOH = 2.2A, and in

hold mode IOH must be held under IOH = 1.8A.

3. Thermal design

[Operating range in which a heat sink is not used]

This section discusses the safe operating range when no heat sink is used.

In the maximum ratings specifications, Tc max is specified to be 105°C, and when mounted in an actual end product

system, the Tc max value must never be exceeded during operation. Tc can be expressed by formula (A) below, and

thus the range for

ΔTc must be stipulated so that Tc is always under 105°C.

Tc = Ta +

ΔTc

(A)

Ta: Hybrid IC (HIC) ambient temperature,

ΔTc: Temperature increase across the aluminum substrate

As shown in figure 5, the value of

ΔTc increases as the hybrid IC internal average power dissipation PD increases.

As shown in figure 4, PD increases with the motor current. Here we describe the actual PD calculation using the

example shown in the motor current timing chart in figure 2.

Since there are periods when current flows and periods when the current is off during actual motor operation, PD

cannot be determined from the data presented in figure 4. Therefore, we calculate PD assuming that actual motor

operation consists of repetitions of the operation shown in figure 2.

Figure 2 Motor Current Timing

T1

T2

T0

T3

-IO1

IO2

IO1

Motor phase current

(sink side)

ITF02175