SPMD250STP

User notes

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9

User notes

9.1

Supply voltage

The recommended operating maximum supply voltage must include the ripple voltage for

the Vs rail, and a 5 V ± 5 % for the Vss line is required.

The two supply voltages must to be correctly sequenced to avoid any possible erroneous

positioning of the power stages. The correct power-up and power-down sequences are:

●

Power-up

1.Vss (5 V) is applied with Enable = Low

2. Vs (the motor supply voltage) is applied

3. Enable is brougth High

●

Power-down

1.Enable is brougth Low

2. Vs is switched off

3. Vss is switched off.

9.2

Case grounding

The module case is internally connected to pin 1 and 13. To obtain additional effective EMI

shield, the PCB area below the module can be used as an effective sixth side shield.

9.3

Thermal characteristics

The case-to-ambient thermal resistance is 5 °C/W. This produces a 50 °C temperature

increase of the module surface for 10 W of internal dissipation.

According to ambient temperature and/or to power dissipation, an additional heatsink or

forced ventilation may be required. (See derating curves Figure 16).

9.4

Supply line impedance

The module has an internal capacitor connected accross the supply pins (18 and 13) to

assure the circuit stability. This capacitor cannot handle high values of current ripple, and

would be permanently damaged if the primary energy source impedance is not adequate.

The use of a low ESR, high ripple current 470 µF capacitor located as close to the module

as possible is recommended.

When space is a limitation, a 22 µF ceramic multilayer capacitor connected across the

module input pins must be used.