SFFSA43 December   2024 LM5125-Q1

 

  1.   1
  2.   Trademarks
  3. 1Overview
  4. 2Functional Safety Failure In Time (FIT) Rates
    1. 2.1 VQFN Package
  5. 3Failure Mode Distribution (FMD)
  6. 4Pin Failure Mode Analysis (Pin FMA)
    1. 4.1 VQFN Package
  7. 5Revision History

4.1 VQFN Package

Figure 4-1 shows the LM5125-Q1 pin diagram for the VQFN package. For a detailed description of the device pins, see the Pin Configuration and Functions section in the LM5125-Q1 data sheet.

Figure 4-1 Pin Diagram (VQFN) Package
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
DLY 1 If average input current loop feature is used the average input current loop is not get activated. B
D
SS 2 Device does not start, no switching. B
COMP 3 VOUT out of regulation, not switching. B
AGND 4 No effect. D
CSN1 5 Device can be damaged if the differential voltage exceeds the 0.3V absolute maximum rating. A
CSP1 6 Device can be damaged if the differential voltage exceeds the 0.3V absolute maximum rating. A
VOUT 7 External components can be damaged. Device potentially goes into latch state or does not start. B
HO1 8 Phase 1 high-side driver can be damaged when device starts switching. A
HB1 9 Device can be damaged when BOOT charging starts. A
SW1 10 No energy transferred from input to output. B
LO1 11 Phase 1 low-side driver can be damaged when device starts switching. A
VCC 12 Loss of VCC regulation, no switching. B
PGND 13 No effect. D
LO2 14 Phase 1 low-side driver can be damaged when device starts switching. A
SW2 15 No energy transferred from input to output. B
HB2 16 Device can be damaged when BOOT charging starts. A
HO2 17 Phase 2 high-side driver can be damaged when device starts switching. A
BIAS 18 Device not powered and therefore not functional. B
UVLO/EN 19 Device is disabled. B
CSP2 20 Device can be damaged if the differential voltage exceeds the 0.3V absolute maximum rating. A
CSN2 21 Device can be damaged if the differential voltage exceeds the 0.3V absolute maximum rating. A
RT 22 Device goes to maximum switching frequency >2.2MHz. C
SYNCOUT 23 SYNCOUT-pin can be damaged if device configuration has SYNCOUT function enabled. A
D
SYNCIN 24 Clock synchronization is disabled, device uses internal clock. C
CFG2 25 CFG2 level-1 is forced. C
CFG1 26 CFG1 level-1 is forced. C
CFG0 27 CFG0 level-1 is forced. C
PGOOD 28 Correct output voltage, but loss of power-good functionality. B
MODE 29 Diode emulation mode is activated. No effect if the device is configured for diode emulation mode (MODE = GND). C
D
EN2 30 If second phase is used, second phase is disabled. C
D
ILIM/IMON 31 Average input current loop is not activated. Current monitoring is not working. B
ATRK/DTRK 32 No output voltage regulation. Device enters BYPASS mode after soft start is complete. B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
DLY 1 If delay pin function is used, the delay programming does not work. B
D
SS 2 Short soft-start time. C
COMP 3 Device can be unstable. B
AGND 4 Possible device damage. A
CSN1 5 Loss of current sense signal for phase 1. Peak current limit does not work. B
CSP1 6 Loss of current sense signal for phase 1. Peak current limit does not work. B
VOUT 7 Internal feedback voltage for regulation loop is pulled to GND, VOUT reaches OVP_max. B
HO1 8 Loss of high-side driver. B
HB1 9 Loss of boot voltage and hence high-side driver. B
SW1 10 Loss of high-side driver. B
LO1 11 Low-side MOSFET never switched for phase 1. B
VCC 12 No stable VCC to sustain normal operation. B
PGND 13 Possible device damage. A
LO2 14 Low-side MOSFET never switched for phase 2. B
SW2 15 Loss of high-side driver. B
HB2 16 Loss of boot voltage and hence high side driver. B
HO2 17 Loss of high side driver. B
BIAS 18 Device not powered and therefore not functional. B
UVLO/EN 19 Device is disabled. B
CSP2 20 Loss of current sense signal for phase 2. Peak current limit does not work. B
CSN2 21 Loss of current sense signal for phase 2. Peak current limit does not work. B
RT 22 Minimum frequency is set. C
SYNCOUT 23 Primary functions normally. Secondary does not get clock in multi-device configuration. C
B
SYNCIN 24 Clock synchronization is not working, device uses internal clock. C
CFG2 25 CFG2 level-16 is forced. C
CFG1 26 CFG1 level-16 is forced. C
CFG0 27 CFG0 level-16 is forced. C
PGOOD 28 Correct output voltage, but loss of power-good functionality. B
MODE 29 No effect if DEM mode is active, otherwise DEM mode is activated. D
C
EN2 30 Second phase enable potentially does not function as intended. C
ILIM/IMON 31 Device operates in average input current limit loop operation, VOUT drops and is therefore out of regulation. B
ATRK/DTRK 32 Device goes to OVPmax. B
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Shorted to Description of Potential Failure Effects Failure Effect Class
DLY 1 SS Loss of delay function, average input current loop does not function as intended. B
SS 2 COMP Device operates in peak current limit and output voltage rises to OVPmax. B
COMP 3 AGND VOUT regulation loop does not function, internal supply can collapse. B
AGND 4 CSN1 Device can be damaged due to the differential voltage exceeds the 0.3V absolute maximum rating. A
CSN1 5 CSP1 Loss of current sense information. Circuit possibly unstable. B
CSP1 6 VOUT Output shorted to input supply. No output regulation. B
VOUT 7 HO1 Possible device damage as HO to switch exceeds absolute maximum voltage rating. A
HO1 8 HB1 Possible device damage when switching starts. A
HB1 9 SW1 Loss of high side driver. B
SW1 10 LO1 Possible device damage as absolute maximum rating exceeded at LO-pin. A
LO1 11 VCC LO not switching. Possible device damage when switching starts. A
VCC 12 PGND No VCC rail, no switching. B
PGND 13 LO2 Device can be damaged when switching starts. A
LO2 14 SW2 Possible device damage as absolute maximum rating exceeded at LO-pin. A
SW2 15 HB2 Loss of high side driver. B
HB2 16 HO2 Possible device damage when switching starts. A
HO2 17 BIAS Possible damage as HO2-pin can exceed the HO2 to SW2 absolute maximum voltage rating. A
BIAS 18 UVLO/EN Loss of UVLO function, device always enabled. B
C
UVLO/EN 19 CSP2 Wrong current sense information, current limit can be wrong. B
CSP2 20 CSN2 Loss of current sense information. Circuit possibly unstable. B
CSN2 21 RT Possible device damage. Exceeds absolute maximum voltage rating for RT. A
RT 22 SYNCOUT Device operates at maximum switching frequency at start-up. When SYNCOUT starts switching, switching is unstable. C
SYNCOUT 23 SYNCIN Loss of frequency sync function, unstable switching frequency. B
SYNCIN 24 CFG2 Loss of frequency sync function and/or wrong configuration 2. B
CFG2 25 CFG1 Wrong configuration 1 and/or configuration 2. B
CFG1 26 CFG0 Wrong configuration 1 and/or configuration 0. B
CFG0 27 PGOOD Loss of configuration 0 function. B
PGOOD 28 MODE MODE function effected, device can function in incorrect operation mode based on PGOOD output. C
MODE 29 EN2 Wrong operation MODE or phase 2 enabled or disabled incorrectly depending on what voltage is driven. B
EN2 30 ILIM/IMON If EN2 is driven high, then the device is forced to function in average input current limit mode. If driven low, loss of ILIM/IMON function. B
ILIM/IMON 31 ATRK/DTRK Output voltage not regulated to target intended value and loss of IMON/ILIM function. B
ATRK/DTRK 32 DLY Output voltage is not regulated to target intended value, average input current limit does not work as intended. B
Table 4-5 Pin FMA for Device Pins Short-Circuited to VI
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
DLY 1 Possible device damage. Exceeds absolute maximum voltage rating. A
SS 2 Possible device damage. Exceeds absolute maximum voltage rating. A
COMP 3 Possible device damage. Exceeds absolute maximum voltage rating. A
AGND 4 Possible device damage. Exceeds absolute maximum voltage rating. A
CSN1 5 Loss of current sense signal. Circuit possibly unstable. B
CSP1 6 Normal operation. D
VOUT 7 Loss of VOUT regulation as output voltage is forced to VI. B
HO1 8 Possible device damage as HO1-pin can exceed the HO1 to SW1 absolute maximum voltage rating. A
HB1 9 Possible device damage as HB1 exceeds HB1 to SW1 absolute maximum voltage rating. A
SW1 10 No energy is transferred from input to output. B
LO1 11 Possible device damage. Exceeds absolute maximum voltage rating. A
VCC 12 Possible device damage. Exceeds absolute maximum voltage rating. A
PGND 13 Possible device damage. A
LO2 14 Possible device damage. Exceeds absolute maximum voltage rating. A
SW2 15 No energy is transferred from input to output. B
HB2 16 Possible device damage as HB2 exceeds HB2 to SW2 absolute maximum voltage rating. A
HO2 17 Possible device damage as HO2 pin can exceed the HO2 to SW2 absolute maximum voltage rating. A
BIAS 18 Normal operation. D
UVLO/EN 19 No UVLO functionality, device is enabled or disabled with VI. B
C
CSP2 20 Normal operation. D
CSN2 21 Loss of current sense signal. Circuit possibly unstable. B
RT 22 Possible device damage. Exceeds absolute maximum voltage rating. A
SYNCOUT 23 Possible device damage. Exceeds absolute maximum voltage rating. A
SYNCIN 24 Possible device damage. Exceeds absolute maximum voltage rating. A
CFG2 25 Possible device damage. Exceeds absolute maximum voltage rating. A
CFG1 26 Possible device damage. Exceeds absolute maximum voltage rating. A
CFG0 27 Possible device damage. Exceeds absolute maximum voltage rating. A
PGOOD 28 Possible device damage. Exceeds absolute maximum voltage rating. A
MODE 29 Possible device damage. Exceeds absolute maximum voltage rating. A
EN2 30 Possible device damage. Exceeds absolute maximum voltage rating. A
ILIM/IMON 31 Possible device damage. Exceeds absolute maximum voltage rating. A
ATRK/DTRK 32 Possible device damage. Exceeds absolute maximum voltage rating. A