L6759D datasheet(31/51 Pages) STMICROELECTRONICS

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L6759D

Output voltage monitoring and protection

Doc ID 023240 Rev 1

31/51

7.2.3

Single-phase section

The L6759D monitors both the per-phase currents and allows the setting of an OC threshold

as follows:

●

Per-phase OC. Maximum information current per-phase (ISINFOx) is internally limited to

µA. This end-of-scale current (ISOC_TH) is compared with the information current

generated for each phase (ISINFOx). If the current information for the single-phase

exceeds the end-of-scale current (i.e. if ISINFOx > ISOC_TH), the device turns on the LS

MOSFET until the threshold is re-crossed (i.e. until ISINFOx < ISOC_TH).

Typical design is dependant on the application TDC and max. current supported. The

typical design flow is the following:

–

Define the maximum total output current (ISOC_TOT) according to system

requirements (ISMAX, ISTDC).

–

Design the per-phase OC and RSG resistor in order to have ISINFOx = ISOC_TH (35

µA) when ISOUT = ISOC_TOT current. It results:

Equation 16

where DCR is the DC resistance of the inductors. RSG should be designed in worst-

case conditions.

–

Adjust the defined values according to the bench-test of the application.

01h, 02h

1.650 V

2.500 V

Table 9.

Multi-phase section OC scaling and power states (continued)

Power state [Hex]

OC level (VOC_TOT)

SOC_TOT

DCR

⋅

SOCTH

---------------------------------------------

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