SLLSFT0 December 2022 ISOW7742-Q1
This section provides a failure mode analysis (FMA) for the pins of the ISOW7742-Q1 in 20-DFM package. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
Table 4-2 through Table 4-5 also indicate how these pin conditions can affect the device as per the failure effects classification in Table 4-1.
| Class | Failure Effects |
|---|---|
| A | Potential device damage that affects functionality. |
| B | No device damage, but loss of functionality. |
| C | No device damage, but performance degradation. |
| D | No device damage, no impact to functionality or performance. |
Figure 4-1 shows the ISOW7742-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the ISOW7742-Q1 data sheet.
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VIO | 1 | No power to the IO on side-1. Observe that the absolute maximum ratings for all IO pins of the device are met; otherwise device damage may be plausible. OUTx states undetermined. | A |
| INA | 2 | Input signal shorted to ground, so output (OUTA) stuck to low. Communication from INA to OUTA corrupted. | B |
| INB | 3 | Input signal shorted to ground, so output (OUTB) stuck to low. Communication from INB to OUTB corrupted. | B |
| OUTC | 4 | OUTC stuck low. Data communication from INC to OUTC lost. Device damage possible if INC is driven high for extended period of time. | A |
| OUTD | 5 | OUTD stuck low. Data communication from IND to OUTD lost. Device damage possible if IND is driven high for extended period of time. | A |
| GNDIO | 6 | Device continues to function as expected. Normal operation. | D |
| EN_IO1 | 7 | Side 1 IO enable pin shorted to ground, so INA, INB and INC are disable and OUTD is in a high impedance state. | B |
| EN/FLT | 8 | Power converter enable pin shorted to ground, so the integrated DC-DC power converter is disabled | B |
| VDD | 9 | No power to side 1 DC-DC converter. Device damage may be plausible if high current flow from the VDD to ground | A |
| GND1 | 10 | Device continues to function as expected. Normal operation. | D |
| GND2 | 11 | Device continues to function as expected. Normal operation. | D |
| VISOOUT | 12 | Isolated power converter output pin shorted to ground. Device damage may be plausible if high current flow from the VISOOUT to ground | A |
| VSEL | 13 | VSEL shorted to ground, so VISOUT is stuck at 3.3V. | B |
| EN_IO2 | 14 | Side 2 IO enable pin shorted to ground, so IND is disable and OUTA, OUTB and OUTC are in a high impedance state. | C |
| GISOIN | 15 | Device continues to function as expected. Normal operation. | D |
| IND | 16 | Input signal shorted to ground, so output (OUTD) stuck to low. Communication from IND to OUTD corrupted. | B |
| INC | 17 | Input signal shorted to ground, so output (OUTC) stuck to low. Communication from INC to OUTC corrupted. | B |
| OUTB | 18 | OUTB stuck low. Data communication from INB to OUTB lost. If INB is driven high, this failure can create short circuit of VISO to GND2. | B |
| OUTA | 19 | OUTA stuck low. Data communication from INA to OUTA lost. If INA is driven high, this failure can create short circuit of VISO to GND2. | B |
| VISOIN | 20 | Side 2 supply volatge shorted to ground, so no power to side 2. If VISOIN is connected to VISOOUT, device damage may be plausible if high current flow from the VDD to ground | A |
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VIO | 1 | Operation undetermined. Either device is unpowered and OUTx undetermined or through internal ESD diode on INA/INB/INC pin, device can power up if any IN is driven to logic high and has sourcing capability. ESD diode from IN to VCC conducts the regular operating current, hence device damage plausible. | A |
| INA | 2 | No communication to INA channel possible. OUTA stuck to default state (High for ISOW7742-Q1 and Low for ISOW7742F-Q1). | B |
| INB | 3 | No communication to INB channel possible. OUTB stuck to default state (High for ISOW7742-Q1 and Low for ISOW7742F-Q1). | B |
| OUTC | 4 | State of OUTC undetermined. Data communication from INC to OUTC lost. | B |
| OUTD | 5 | State of OUTD undetermined. Data communication from IND to OUTD lost. | B |
| GNDIO | 6 | No Return ground for IO. IO unpowered on side 1. | B |
| EN_IO1 | 7 | Side 1 enable pin is open, so OUTD is always enabled. | B |
| EN/FLT | 8 | EN/FLT is open, so integrated DC/DC converter state is undefiend | B |
| VDD | 9 | No power to the integrated DC/DC converter. VISOOUT is undefined. | B |
| GND1 | 10 | No Return ground for integrated DC/DC connverter. VISOOUT is undefined. | B |
| GND2 | 11 | No Return ground for VISOOUT. Side 2 IO has no power. | B |
| VISOOUT | 12 | VISOOUT is open, so VISOIN has no power | B |
| VSEL | 13 | VSEL is open, so default to VISOOUT 5V | B |
| EN_IO2 | 14 | Side 2 enable pin is open, so OUTA, OUTB, and OUTC are always enabled. | B |
| GISOIN | 15 | No Return ground for VISOIN. No power to the IO. | B |
| IND | 16 | No communication to IND channel possible. OUTD stuck to default state (High for ISOW7742-Q1 and Low for ISOW7742F-Q1). | B |
| INC | 17 | No communication to INC channel possible. OUTC stuck to default state (High for ISOW7742-Q1 and Low for ISOW7742F-Q1). | B |
| OUTB | 18 | State of OUTB undetermined. Data communication from INB to OUTB lost. | B |
| OUTA | 19 | State of OUTA undetermined. Data communication from INA to OUTA lost. | B |
| VISOIN | 20 | No power to VISOIN, so IO has no power. | B |
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|---|
| VIO | 1 | INA | If INA is low, No power to the device on side-1. Observe that the absolute maximum ratings for all pins of the device are met; otherwise device damage may be plausible. | A |
| INA | 2 | INB | ommunication corrupted for either INA or INB channel. | B |
| INB | 3 | OUTC | Communication corrupted for either or both channels. With opposite logic state on both channels, high current can flow between supply and ground and cause possible device damage. | A |
| OUTC | 4 | OUTD | Communication corrupted for either or both channels. With opposite logic state on both channels, high current can flow between supply and ground and cause possible device damage. | A |
| OUTD | 5 | GNDIO | OUTD shorted to ground. High current can flow between OUTD and ground and cause possible device damage. | A |
| GNDIO | 6 | EN_IO1 | Disables OUTD output buffer. Communication for channel D corrupted. | B |
| EN_IO1 | 7 | EN/FLT | IO and integrated DC/DC conveter are enabled or disabled simultaneously. | B |
| EN/FLT | 8 | VDD | Integrated DC/DC converter is always enabled | B |
| VDD | 9 | GND1 | High current can flow between DC/DC converter supply and ground and cause possible device damage. | A |
| GND1 | 10 | VDD | Already considered in above row. | A |
| GND2 | 11 | VISOOUT | Integrated DC/DC converter output shorted to ground, so high current can flow between DC/DC converter output and ground and cause possible device damage. | A |
| VISOOUT | 12 | VSEL | If VSEL is logic low, high current can flow between VISOOUT and VSEL and cause possible device damage. | A |
| VSEL | 13 | EN_IO2 | VSEL and EN_IO2 are coupled together. | B |
| EN_IO2 | 14 | GISOIN | Side 2 IO is disabled, so IND is disable and OUTA, OUTB and OUTC are in a high impedance state. | B |
| GISOIN | 15 | IND | OUTD is always low. | B |
| IND | 16 | INC | Communication corrupted for either IND or INC channel | B |
| INC | 17 | OUTB | Communication corrupted for either or both channels. With opposite logic state on both channels, high current can flow between supply and ground and cause possible device damage. | A |
| OUTB | 18 | OUTA | Communication corrupted for either OUTA or OUTB channel. Device damage possible if INA and INB try to drive opposite logic state for extended duration creating a short between supply and ground on side-2. | A |
| OUTA | 19 | VISOIN | Side 2 has no power if OUTA is driven low. | B |
| VISOIN | 20 | OUTA | Already considered in above row. | B |
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VIO | 1 | No effect. Normal operation. | D |
| INA | 2 | INA pin stuck high. Communication corrupted. OUTA state high. | B |
| INB | 3 | INB pin stuck high. Communication corrupted. OUTB state high. | B |
| OUTC | 4 | OUTC stuck high. Data communication from INC to OUTC lost. Device damage possible if INC is driven low for extended period of time. | A |
| OUTD | 5 | OUTD stuck high. Data communication from INC to OUTC lost. Device damage possible if IND is driven low for extended period of time causing a short between supply and ground on side-1 | A |
| GNDIO | 6 | This will create supply to ground short on PCB causing the device to turn off. | B |
| EN_IO1 | 7 | Functionality to disable output buffer OUTD lost. Communication for all channels normal. | B |
| EN/FLT | 8 | Functionality to disable integrated DC/DC converter lost. | B |
| VDD | 9 | No effect. Normal operation. | D |
| GND1 | 10 | This will create supply to ground short on PCB causing the device to turn off. | B |
| GND2 | 11 | This will cause VISOOUT to ground short making the device go in short circuit protection mode. | B |
| VISOOUT | 12 | Device continues to function as expected. Normal operation. | D |
| VSEL | 13 | This will cause VISOOUT to default at 5V | B |
| EN_IO2 | 14 | Functionality to disable output buffer OUTD lost. Communication for all channels normal. | B |
| GISOIN | 15 | No effect. Normal operation. | D |
| IND | 16 | IND pin stuck high. Communication corrupted. OUTD state high. | B |
| INC | 17 | INC pin stuck high. Communication corrupted. OUTC state high. | B |
| OUTB | 18 | OUTB stuck high. Communication disrupted. If INB is low for extended duration, OUTB being stuck high creates a short and can cause device go to short circuit protection mechanism. | B |
| OUTA | 19 | OUTA stuck high. Communication disrupted. If INA is low for extended duration, OUTA being stuck high creates a short and can cause device go to short circuit protection mechanism. | B |
| VISOIN | 20 | Device continues to function as expected. Normal operation. | D |