L6717ATR datasheet(42/57 Pages) STMICROELECTRONICS

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Output voltage monitoring and protections

L6717A

42/57

DocID024465 Rev 1

Output voltage monitoring and protections

L6717A monitors the regulated voltage of both sections through pin VSEN and NB_VSEN in

order to manage OV, UV and PWRGOOD. The device shows different thresholds when in

different operative conditions but the behavior in response to a protection event is still the

same as described below.

Protections are active also during soft-start (See

Section 7.8) while they are masked during

OTF-VID transitions with an additional delay to avoid false triggering.

8.1

Programmable overvoltage (I2DIS = 3.3 V)

When power manager I

C is disabled, L6717A provides the possibility to adjust OV

threshold (common for both Sections) through the SDA/OVP pin. Connecting the pin to

SGND through a resistor R

OVP

, the OVP threshold becomes the voltage present at the pin.

Since the SDA/OVP pin sources a constant I

OVP

=10

μA current, the programmed over

voltage threshold will be OVP

OVP

*10

μA.

Table 21.L6717A protection at a glance

L6717A

Section

CORE

North bridge

Overvoltage

(OV)

SVI / PVI: +250mV above reference, programmable by power manager I2C bus.

I2CDIS = 3.3V: Programmable through SDA/OVP pin.

V_FIX: Fixed to 1.8V.

Action: IC latch; LS=ON & PWMx = 0 (if applicable);

Other section (SVI only): HiZ; FLT driven high.

Undervoltage (UV)

VSEN, NB_VSEN = VID -400mV. Active after Ref > 500mV

Action: IC latch; both sections HiZ; FLT driven high.

PWRGOOD

PWRGOOD is the logic AND between internal CORE and NB PGOOD in SVI

mode while is the CORE section PGOOD in PVI mode.

Each PGOOD is set to zero when the related voltage falls below the

programmed reference -250mV.

Action: Section(s) continue switching, PWRGOOD driven low.

VSEN, NB_VSEN

disconnection

Set when VSEN > CS1N +600mV.

Action: UV-Like

Set when VSEN > NB_CSN +600mV.

Action: UV-Like (SVI only)

FBG, NB_FBG

disconnection

Internal comparator across the opamp to recover from GND losses.

Action: UV-Like

Overcurrent (OC)

Current monitor across inductor DCR.

Dual protection, per-phase and

average.

Action: UV-Like

Current monitor across inductor DCR.

Constant current.

Action: UV-Like

On-the-fly VID

Protections masked with the exception of OC with additional 16 clock delay to

prevent from false triggering (both SVI and PVI).

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