What Is the Difference Between the “VS2” and “VS1” Variants of the TLF35584QVVS2XUMA1?
The TLF35584QVVS2XUMA1 is a functional safety power management IC (PMIC) from Infineon’s OPTIREG™ family, supplying a microcontroller, transceivers, and sensors from a wide automotive input range. The device is offered in two primary voltage variants, designated VS1 and VS2 in the ordering code. The difference between them is narrow and specific: it is the output voltage of the two rails that directly serve the microcontroller. The VS1 variant provides 5.0 V on those rails, while the VS2 variant provides 3.3 V [3†L5-L8]. Every other functional block, safety mechanism, and peripheral supply remains the same.
1. The Rails That Change: QUC and QST
The TLF35584QVVS2XUMA1 generates multiple regulated outputs from a boost/buck pre-regulator. Two of these outputs are tied to the VS1/VS2 distinction. The first is QUC, the main low-dropout post-regulator that supplies the microcontroller core and I/O. The second is QST, the standby regulator that keeps a small portion of the system alive when the main supply is off [5†L17-L22].
In the VS1 variant, both QUC and QST are regulated to 5.0 V. QUC delivers up to 600 mA, and QST delivers up to 10 mA. In the VS2 variant, both rails are regulated to 3.3 V with the same current capabilities: 600 mA on QUC and 10 mA on QST [3†L5-L8]. The current ratings do not change between variants. Only the regulated voltage setpoint differs.
2. What Remains Identical
The rest of the power tree and the entire safety architecture are unaffected by the VS1/VS2 choice. The communication supply (QCO) remains 5.0 V at 200 mA on both variants. The reference voltage (QVR) remains 5.0 V ±1% at 150 mA, and the two sensor trackers (QT1 and QT2) follow that reference at 150 mA each [3†L4-L7].
The functional safety features are also unchanged. Both variants support ISO 26262 up to ASIL-D, with independent undervoltage/overvoltage monitoring, a window watchdog and a functional watchdog, an error monitoring pin, a safe-state controller with two programmable-delay outputs, and a 16-bit SPI interface for configuration and diagnostics [5†L23-L28]. The AEC-Q100 Grade 0 qualification and the -40°C to +150°C junction temperature range apply equally to both [3†L22-L22]. In short, VS1 and VS2 are the same PMIC with a different factory-set output voltage on the microcontroller-facing rails.
3. How the Choice Is Made
The selection is driven entirely by the logic level of the microcontroller being supplied. A 5 V microcontroller requires the VS1 variant; a 3.3 V microcontroller requires the VS2 variant [2†L8-L12]. Infineon’s AURIX™ TC2xx and TC3xx families, for example, are 3.3 V devices, so the VS2 variant is the appropriate match when using those microcontrollers with the TLF35584 [2†L4-L7]. Legacy 5 V microcontrollers or systems that still operate on a 5 V rail would use VS1.
The variant choice also carries through to the package and ordering code. Both VS1 and VS2 are available in the thermally enhanced PG-VQFN-48 package and in the PG-LQFP-64 package. The package and the voltage variant are independent selections, giving four ordering combinations [3†L15-L19].
4. Direct Comparison
| Parameter | TLF35584 VS1 | TLF35584 VS2 |
|---|---|---|
| Microcontroller supply (QUC) | 5.0 V / 600 mA | 3.3 V / 600 mA |
| Standby supply (QST) | 5.0 V / 10 mA | 3.3 V / 10 mA |
| Communication supply (QCO) | 5.0 V / 200 mA | 5.0 V / 200 mA |
| Reference voltage (QVR) | 5.0 V ±1% / 150 mA | 5.0 V ±1% / 150 mA |
| Sensor trackers (QT1/QT2) | 150 mA each, tracking QVR | 150 mA each, tracking QVR |
| Pre-regulator input range | 3.0 V to 40 V | 3.0 V to 40 V |
| Functional safety | ISO 26262 ASIL-D | ISO 26262 ASIL-D |
| Watchdogs | Window + functional | Window + functional |
| SPI interface | 16-bit | 16-bit |
| Junction temperature | -40°C to +150°C | -40°C to +150°C |
| Automotive qualification | AEC-Q100 Grade 0 | AEC-Q100 Grade 0 |
| Package options | VQFN-48 / LQFP-64 | VQFN-48 / LQFP-64 |
5. Questions and Answers
Q: Can I use the VS2 variant to supply a 5 V microcontroller by adjusting external components?
A: No. The QUC and QST output voltages are factory-set at the silicon level for each variant. They are not adjustable through external resistors or SPI configuration. If the microcontroller requires 5 V, the VS1 variant must be ordered. Attempting to operate a 5 V microcontroller from the VS2 variant’s 3.3 V QUC rail will result in insufficient supply voltage and unreliable operation.
Q: Does the VS2 variant have a different current capability on QUC or QST?
A: No. Both variants are rated for 600 mA on QUC and 10 mA on QST. The current capability is identical; only the regulated voltage differs. The thermal performance and the pre-regulator current limit (1.25 A) are also the same [1†L4-L7].
Q: Is the safety documentation different between VS1 and VS2?
A: No. Both variants are covered by the same Safety Manual and Safety Analysis Summary Report, and both support ASIL-D applications. The safety mechanisms, monitoring thresholds, and diagnostic coverage are defined by the device architecture, not by the output voltage option. The functional safety case can be built identically around either variant.
Q: Which variant is more common in new automotive designs?
A: The VS2 (3.3 V) variant has become the more common choice for new designs, driven by the widespread adoption of 3.3 V microcontrollers in automotive ECUs, including Infineon’s AURIX™ TC3xx family and comparable devices from other vendors. The VS1 (5.0 V) variant remains relevant for legacy platforms or systems that retain 5 V logic on the microcontroller side [2†L4-L12].
6. Conclusion
The difference between the TLF35584 VS1 and VS2 variants is the output voltage of the two rails that directly serve the microcontroller: 5.0 V on VS1 and 3.3 V on VS2. The current ratings, the communication and reference supplies, the sensor trackers, the safety architecture, the watchdogs, the SPI interface, the temperature range, and the qualification standard are identical. The choice is therefore a simple one: match the variant to the microcontroller’s logic level. For a 3.3 V microcontroller, VS2 is the correct part; for a 5 V microcontroller, VS1 is. No other engineering trade-off is involved.
