L6701TR datasheet(30/44 Pages) STMICROELECTRONICS

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13 Output voltage Monitor and Protections

L6701

30/44

Figure 13. Output Voltage Protections and typical principle connections

13.3

Over Voltage

Once VCC crosses the turn-ON threshold and the device is enabled (EN = Free), L6701

provides an Over Voltage Protection according to the DAC_SEL status: when the voltage

sensed by VSEN overcomes the OVP threshold, the controller permanently switches on all the

low-side MOSFETs and switches off all the high-side MOSFETs in order to protect the load.

The FAULT pin is driven high (5V) and power supply or EN pin cycling is required to restart

operations.

The OVP (and Pre-OVP) Threshold varies according to the operative mode selected as

reported in Table 10.

13.4

Feedback Disconnection

L6701 allows to monitor the output voltage in two different points:

●

Remotely, through the remote buffer, across VSEN

●

Locally across the CS- pin (negligibly offset by

By comparing the voltage present at these two different locations, L6701 is able to understand

if the output voltage feedback is connected. When CS- is more than 1V higher than VSEN,

(See Figure 14) the device stops switching with the low side MOSFETs permanently ON and

drives high the FAULT pin. The condition is latched until VCC or EN cycled.

Table 10.

OVP and Preliminary OVP Thresholds

DAC_SEL

Operative Mode

Pre-OVP

OVP

0VR9

2.1

82k

Ω to SGND

VR10

1.9

Open

1.9

VCC

+12V

+5V

Vcc

UVLO

OVP

UVLO

VCC

Preliminary OVP Enabled

FBR Monitored

No Protection

Provided

(EN = Free)

OVP Protection

VSEN Monitored

(EN = 0)

Preliminary OVP

FBR/DACSEL Monitor

C S

⋅

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