L9001 datasheet(21/38 Pages) STMICROELECTRONICS

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DS12089 Rev 2

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L9001

Diagnosis

Each power supply line generated by the device is monitored against over voltage, under

voltage and provides an internal current limitation circuit; besides the device provides

additional diagnosis functions: watchdog, over temperature, VS UV/OV and latch mode.

VDD1 regulator output is monitored through VR1 pin and if the voltage goes below (above)

the specified threshold VR1_uv (VR1_ov) for more than tFILT_uv_VR1 (tFILT_ov_VR1) filter time,

RSTN1 is driven low; when the fault disappears, RSTN1 is released after the specified time

tRSTN1_act.

VDD2 regulator output is monitored through FB2 pin and if the voltage goes below (above)

the specified threshold VR2_uv (VR2_ov) for more than tFILT_uv_VR2 (tFILT_ov_VR2) filter time,

RSTN2 is driven low; when the fault disappears, RSTN2 is released after the specified time

tRSTN2_act.

ADCLDO regulator output is monitored through VADC pin and if the voltage goes below

(above) the specified threshold VADC_uv (VADC_ov) for more than tFILT_uv_VADC

(tFILT_ov_VADC) filter time, ADCMON is driven low; when the fault disappears, ADCMON is

released after the specified time tADCMON_act.

As supervision watchdog function, the WDI input is monitored and WDO output is driven low

in case of faults (see Section 7 for details)

Internal junction temperature is monitored and when Tj > TW_H, TWN output is driven low

and it is released when Tj < TW_L (hysteresis implemented); when Tj > TSD, L9001 shut

down regulators entering a protection mode called SAFE state (see Section 8.2.5 for

details). L9001 goes back to ACTIVE mode when Tj < TW_L.

TWN and WDO are open drain. RSTN1, RSTN2 and ADCMON all have an internal resistive

pull-up R_INT_RPU to VDDIO. RSTN1, RSTN2 and ADCMON are driven low level at

power-up when WAKE is greater than WAKE_Hth after WPH filter time and are released

after their relative output voltages (VR1, VR2 and VADC) have risen above their under

voltage thresholds.

VS input pin is monitored and in case one of the following conditions applies the device

goes in a protection mode called SAFE state:



VS > VS_ov_h for a period longer than tFILT_VS_ov,

–

L9001 goes back to ACTIVE mode if VS < VS_ov_l for a period longer than

tFILT_VS_ov



VS < VS_uv_l for a period longer than tFILT_VS_uv,

–

L9001 goes back to ACTIVE mode if VS > VS_uv_h for a period longer than

tFILT_VS_uv

Internal CP voltage is monitored as well and when CP<CP_uv for a period longer than

tFILT_CP_uv L9001 shuts down regulators and enters SAFE state; it goes back to ACTIVE

mode if CP>CP_uv for a period longer than tFILT_CP_uv.

L9001 provides a feature, called latch state, that disables the system in case a systematic

fault is repetitively detected on CP_uv, watchdog or thermal shutdown events. For detailed

description see LATCH mode description in Section 8.2.6.

L9001 Datasheet(PDF) 21 Page - STMicroelectronics

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