SFFSA43A December   2024  – September 2025 LM5125-Q1 , LM51251A-Q1 , LM5125A-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 LM5125-Q1 (VQFN) Package
    2. 4.2 LM5125A-Q1 (VQFN) Package
    3. 4.3 LM51251A-Q1 (VQFN) Package
  7. 5Revision History

4.1 LM5125-Q1 (VQFN) Package

Figure 4-1 shows the pin diagram for the LM5125-Q1 device. 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 The average-input-current loop is not activated when the average-input-current loop feature is used. B
D
SS 2 The device does not start; no switching. B
COMP 3 VOUT is out of regulation; not switching. B
AGND 4 No effect. D
CSN1 5 The device is potentially damaged if the differential voltage exceeds the absolute maximum rating of 0.3V. A
CSP1 6 The device is potentially damaged if the differential voltage exceeds the absolute maximum rating of 0.3V. A
VOUT 7 The external components are potentially damaged. The device potentially goes into a latch state or does not start. B
HO1 8 The phase-1 high-side driver is potentially damaged when the device starts switching. A
HB1 9 The device is potentially damaged when BOOT charging starts. A
SW1 10 No energy is transferred from the input to the output. B
LO1 11 The phase-1 low-side driver is potentially damaged when the device starts switching. A
VCC 12 There is a loss of VCC regulation; no switching. B
PGND 13 No effect. D
LO2 14 The phase-1 low-side driver is potentially damaged when the device starts switching. A
SW2 15 No energy is transferred from the input to the output. B
HB2 16 The device is potentially damaged when BOOT charging starts. A
HO2 17 The phase-2 high-side driver is potentially damaged when the device starts switching. A
BIAS 18 The device is not powered, and therefore, not functional. B
UVLO/EN 19 The device is disabled. B
CSP2 20 The device is potentially damaged if the differential voltage exceeds the absolute maximum rating of 0.3V. A
CSN2 21 The device is potentially damaged if the differential voltage exceeds the absolute maximum rating of 0.3V. A
RT 22 The device goes to the maximum switching frequency of >2.2MHz. C
NC 23 No connection. D
SYNCIN 24 Clock synchronization is disabled; the device uses the internal clock. C
CFG2 25 Level 1 of the CFG2 pin is forced. C
CFG1 26 Level 1 of the CFG1 pin is forced. C
CFG0 27 Level 1 of the CFG0 pin is forced. C
PGOOD 28 The voltage of the output is correct, but there is a loss of functionality at the PGOOD pin. B
MODE 29 Diode emulation mode is activated. There is no effect if the device is configured for diode emulation mode (MODE = GND). C
D
EN2 30 Second phase is disabled if second phase is used. C
D
ILIM/IMON 31 The average-input-current loop is not activated; current monitoring does not work. B
ATRK/DTRK 32 There is no output voltage regulation. The device enters BYPASS mode after the soft start completes. 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 Delayed programming does not work if the delay pin function is used. B
D
SS 2 There is a short soft-start time. C
COMP 3 The device is potentially unstable. B
AGND 4 Device damage is possible. A
CSN1 5 There is a loss of the current sense signal for phase 1. Peak-current limit does not work. B
CSP1 6 There is a loss of the current sense signal for phase 1. Peak-current limit does not work. B
VOUT 7 The internal feedback voltage for the regulation loop is pulled to GND; VOUT reaches OVPmax. B
HO1 8 There is a loss of the high-side driver. B
HB1 9 There is a loss of boot voltage, and hence, a loss of the high-side driver. B
SW1 10 There is a loss of the high-side driver. B
LO1 11 The low-side MOSFET does not switch for phase 1. B
VCC 12 The VCC pin is not stable enough to sustain normal operation. B
PGND 13 Device damage is possible. A
LO2 14 The low-side MOSFET does not switch for phase 2. B
SW2 15 There is a loss of the high-side driver. B
HB2 16 There is a loss of boot voltage, and hence, a loss of the high-side driver. B
HO2 17 There is a loss of the high-side driver. B
BIAS 18 The device is not powered, and therefore, not functional. B
UVLO/EN 19 The device is disabled. B
CSP2 20 There is a loss of the current sense signal for phase 2. Peak-current limit does not work. B
CSN2 21 There is a loss of the current sense signal for phase 2. Peak-current limit does not work. B
RT 22 The minimum frequency is set. C
NC 23 No connection. D
SYNCIN 24 Clock synchronization does not work; the device uses the internal clock. C
CFG2 25 Level 16 of the CFG2 pin is forced. C
CFG1 26 Level 16 of the CFG1 pin is forced. C
CFG0 27 Level 16 of the CFG0 pin is forced. C
PGOOD 28 The output voltage is correct, but there is a loss of functionality at the PGOOD pin. B
MODE 29 There is 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 The device operates in an average-input-current limit loop operation; VOUT drops, and therefore, VOUT is out of regulation. B
ATRK/DTRK 32 The 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 There is a loss of the delay function; the average-input-current loop does not function as intended. B
SS 2 COMP The device operates in peak-current limit and the output voltage rises to OVPmax. B
COMP 3 AGND The VOUT regulation loop does not function, the internal supply potentially collapses. B
AGND 4 CSN1 The device is potentially damaged if the differential voltage exceeds the absolute maximum rating of 0.3V. A
CSN1 5 CSP1 There is a loss of current sense information. The circuit is potentially unstable. B
CSP1 6 VOUT The output is shorted to the input supply. There is no output regulation. B
VOUT 7 HO1 Device damage is possible as the HO1 pin exceeds the absolute maximum voltage rating to switch. A
HO1 8 HB1 Device damage is possible when switching starts. A
HB1 9 SW1 There is a loss of the high-side driver. B
SW1 10 LO1 Device damage is possible as the absolute maximum rating is exceeded at the LO1 pin. A
LO1 11 VCC The LO1 pin does not switch. Device damage is possible when switching starts. A
VCC 12 PGND There is no VCC rail; no switching. B
PGND 13 LO2 Device damaged is possible when switching starts. A
LO2 14 SW2 Device damage is possible as the absolute maximum rating is exceeded at the LO2 pin. A
SW2 15 HB2 There is a loss of the high-side driver. B
HB2 16 HO2 Device damage is possible when switching starts. A
HO2 17 BIAS Device damage is possible as the HO2 pin potentially exceeds the absolute maximum voltage ratings at the pin locations of HO2 to SW2. A
BIAS 18 UVLO/EN There is a loss of the UVLO function; the device is always enabled. B
C
UVLO/EN 19 CSP2 There is incorrect current sense information, the current limit is potentially incorrect. B
CSP2 20 CSN2 There is a loss of current sense information. The circuit is potentially unstable. B
CSN2 21 RT Device damage is possible. The CSN2 pin exceeds the absolute maximum voltage rating for the RT pin. A
RT 22 NC The device potentially operates at the wrong switching frequency. C
NC 23 SYNCIN The device potentially loses the frequency synchronization function; switching frequency is unstable. B
SYNCIN 24 CFG2 There is a loss of the frequency synchronization function or Configuration 2 is incorrect (or both—loss of function and incorrect configuration). B
CFG2 25 CFG1 Configuration 1 or Configuration 2 (or both) are incorrect for the device. B
CFG1 26 CFG0 Configuration 1 or Configuration 2 (or both) are incorrect for the device. B
CFG0 27 PGOOD The device loses the function of Configuration 0. B
PGOOD 28 MODE The MODE function of the device is effected. The device potentially functions in an operation mode that is incorrect based on the PGOOD output. C
MODE 29 EN2 The incorrect operation MODE or phase 2 enables or disables incorrectly, depending on the voltage that is driven. B
EN2 30 ILIM/IMON The device is forced to function in average-input-current limit mode if the EN2 pin is driven high. The function of the ILIM/IMON pin is lost if the EN2 pin is driven low. B
ILIM/IMON 31 ATRK/DTRK The voltage of the output is not regulated to target the intended value, and the function of the IMON/ILIM pin is lost. B
ATRK/DTRK 32 DLY The voltage of the output is not regulated to target the intended value. The 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 Device damage is possible; exceeds the absolute maximum voltage rating. A
SS 2 Device damage is possible; exceeds the absolute maximum voltage rating. A
COMP 3 Device damage is possible; exceeds the absolute maximum voltage rating. A
AGND 4 Device damage is possible; exceeds the absolute maximum voltage rating. A
CSN1 5 There is a loss of the current sense signal. The circuit is potentially unstable. B
CSP1 6 Normal operation. D
VOUT 7 There is a loss of VOUT regulation as the output voltage is forced to VI. B
HO1 8 Device damage is possible as the HO1 pin potentially exceeds the absolute maximum voltage ratings at the pin locations of HO1 to SW1. A
HB1 9 Device damage is possible as the HB1 pin exceeds the absolute maximum voltage ratings at the pin locations of HB1 to SW1. A
SW1 10 Energy is not transferred from input to output. B
LO1 11 Device damage is possible; exceeds the absolute maximum voltage rating. A
VCC 12 Device damage is possible; exceeds the absolute maximum voltage rating. A
PGND 13 Device damage is possible. A
LO2 14 Device damage is possible; exceeds the absolute maximum voltage rating. A
SW2 15 Energy is not transferred from input to output. B
HB2 16 Device damage is possible as the HB2 pin potentially exceeds the absolute maximum voltage ratings at the pin locations of HB2 to SW2. A
HO2 17 Device damage is possible as the HO2 pin potentially exceeds the absolute maximum voltage ratings at the pin locations of HO2 to SW2. A
BIAS 18 Normal operation. D
UVLO/EN 19 No UVLO functionality, the device is enabled or disabled with VI. B
C
CSP2 20 Normal operation. D
CSN2 21 There is a loss of the current sense signal. The circuit is potentially unstable. B
RT 22 Device damage is possible; exceeds the absolute maximum voltage rating. A
NC 23 The device is potentially damaged. A
SYNCIN 24 Device damage is possible; exceeds the absolute maximum voltage rating. A
CFG2/SDA 25 Device damage is possible; exceeds the absolute maximum voltage rating. A
CFG1/SCL 26 Device damage is possible; exceeds the absolute maximum voltage rating. A
CFG0/CFG 27 Device damage is possible; exceeds the absolute maximum voltage rating. A
PGOOD 28 Device damage is possible; exceeds the absolute maximum voltage rating. A
MODE 29 Device damage is possible; exceeds the absolute maximum voltage rating. A
EN2 30 Device damage is possible; exceeds the absolute maximum voltage rating. A
ILIM/IMON 31 Device damage is possible; exceeds the absolute maximum voltage rating. A
ATRK/DTRK 32 Device damage is possible; exceeds the absolute maximum voltage rating. A