Figure 9. 12 V LDO linear regulator typical configuration

VS

12 V

LDO reg

REG12

VS

CREG12

220 nF

100 nF

The regulator supplies the gate drivers and can be used to supply small external loads. The average current

consumption IREG12 is given by the internal consumption of the gate drivers, the current provided to the gates of

the external MOSFETs and the external load consumption, if any. IREG12 cannot exceed IREG12lim.

The internal consumption of the gate drivers is proportional to the switching frequency and its typical value is

reported in Figure 10; this is the overall consumption of the six gate drivers and it is measured without any load

connected on the drivers’ outputs.

Figure 10. Typical current consumption (driver’ outputs unloaded)

On top of this, the current supplied to the external MOSFETs’ gates must be considered. The overall gate current

IG,tot for the six MOSFETs of the power stage can be calculated as:

Equation 1

(1)

IG,tot= 6⋅Qg⋅fSW

where Qg is the gate charge value of the external MOSFETs, taken at gate voltage equal to VREG12 and fSW is the

switching frequency of the MOSFETs (i.e. the frequency of the PWM signals applied to the drivers).

Another aspect to consider for the maximum current of the linear regulator is the power dissipation. An excessive

power dissipation leads to the thermal shutdown of the device ( Section 5.8 ). The total power dissipation of the

regulator PREG12 can be calculated as:

STDRIVE101

12 V LDO linear regulator

DS13472 - Rev 1

page 14/32