L9779WD datasheet(39/170 Pages) STMICROELECTRONICS

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L9779WD

Functional description

169

6.6

Voltage regulators

Figure 15. Structure regulators diagram

The structure of regulators is showed in the above figure.

The 5 V voltage is obtained through a linear regulator using an external N-Mos. The

precision is ± 2% with Imax = 400 mA. The high precision is obtained with a pre-trimmed

reference voltage. The under-voltage condition is monitored through the Smart Reset circuit.

In addition there is an overvoltage monitor that after t_VDD5_OV time switches off the

drivers except the MRD, OUT13, OUT14, OUT21, OUT25. To switch on again the output it

is necessary to send again the START command and to write the CONTROL registers.

It is present a VDD5 over voltage flag, VDD5_OV, that is latched and cleared after reading.

This flag does not inhibit the drivers switch on.

The 3.3 V voltage is obtained through a linear regulator. The precision is ± 2% with

Imax = 100 mA.

Over-current protection is provided and operates together with thermal sensor OT4.

The condition that switches off the V3V3 is the logic and of both Thermal Warning and Over

Current.

The under-voltage condition is monitored and the non latched information is available

V3V3_UV bit.

VTRK1, 2 are two voltage regulators in tracking (±20 mV) with the VDD5 voltage for

Sensors Supply. They can supply sensors with a Imax = 100 mA. The output voltages can

be used in parallel.

VTRK supplies are protected from over voltage due to short to VB with back to back

protection and non latched information is available VTRACK_DIAG bit.

Over-current protection is provided as well and operates together with thermal sensor OT1.

The condition that switches off the VTRK 1, 2 is the logic of thermal warning and over

current.

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