Component Comparison: TCR2EF33,LM(CT) vs L78L33ABUTR
Quick verdict
For low-voltage, low-dropout applications requiring up to 200mA output and an enable pin, the TCR2EF33,LM(CT) is the better choice due to its low dropout voltage and low quiescent current. For designs needing higher input voltage tolerance, thermal protection, or operation up to 125°C, and where output current up to 100mA suffices, the L78L33ABUTR offers better built-in protection and robustness.
Spec comparison table
| Spec | TCR2EF33,LM(CT) | L78L33ABUTR | Notes |
|---|---|---|---|
| Control features | Enable pin | None | Enable pin on TCR2EF33 provides on/off control, useful for power sequencing. |
| Quiescent current (Iq) | 60 µA | 5.5 mA | TCR2EF33’s 60µA quiescent current is ~90x lower, better for battery-powered or low-power designs. |
| Input voltage max | 5.5 V | 30 V | L78L33ABUTR supports much higher input voltage, offering more input supply flexibility. |
| Mounting type | Surface Mount (SC-74A) | Surface Mount (SOT-89-3) | Both surface mount, but different package types affect PCB layout and thermal dissipation. |
| Number of regulators | 1 | 1 | Both single-output regulators. |
| Operating temperature | -40°C to 85°C | -40°C to 125°C | L78L33ABUTR supports wider temperature range, suitable for more demanding environments. |
| Output configuration | Positive | Positive | Both positive fixed output regulators. |
| Max output current | 200 mA | 100 mA | TCR2EF33 supports double the output current of L78L33ABUTR. |
| Output type | Fixed | Fixed | Both fixed 3.3 V output. |
| Output voltage | 3.3 V min | 3.3 V min | Both fixed 3.3 V output; no adjustable option. |
| Package case | SC-74A (SOT-753) | TO-243AA (SOT-89-3) | Different package; TO-243AA offers larger thermal pad area for better heat dissipation. |
| Protection features | Over Current | Over Current, Over Temperature, Short Circuit | L78L33ABUTR has more comprehensive protection features, improving system reliability. |
| PSRR | 73 dB @ 1 kHz | 49 dB @ 120 Hz | TCR2EF33 offers superior PSRR at 1 kHz, better for noise-sensitive analog or RF circuits. |
| Voltage dropout max | 0.2 V @ 150 mA | Not specified | TCR2EF33’s low dropout voltage improves efficiency and headroom in low-voltage designs. |
Design trade-offs
The TCR2EF33,LM(CT) targets low-voltage, low-power applications with a maximum input voltage of only 5.5 V, which restricts its use to regulated or low-voltage DC rails. Its dropout voltage of 0.2 V at 150 mA is low relative to typical 3-terminal regulators, enabling more efficient use of limited input voltage headroom. The very low quiescent current (60 µA) minimizes battery drain or standby power, making it suitable for portable or always-on low-power circuits. The addition of an enable pin facilitates power sequencing or shutdown to further reduce power consumption.
In contrast, the L78L33ABUTR supports a wide input voltage range up to 30 V, accommodating unregulated or widely varying supply rails such as 12 V automotive or industrial power sources. However, this comes with a trade-off: the quiescent current is 5.5 mA, nearly two orders of magnitude higher, which can be prohibitive in low-power designs. The maximum output current is limited to 100 mA, half that of the TCR2EF33, which restricts its use in higher current loads.
Thermally, the L78L33ABUTR’s TO-243AA (SOT-89-3) package offers superior thermal dissipation capabilities compared to the smaller SC-74A package of the TCR2EF33. This is important since the L78L33ABUTR can dissipate more power due to higher input voltage and associated voltage drop. It also includes over-temperature and short-circuit protection, which can prevent damage in harsh environments or during fault conditions, increasing system robustness.
From a layout perspective, the smaller SC-74A package of the TCR2EF33 may be advantageous in dense PCB designs, but careful thermal management is required due to lower dissipation capability. The L78L33ABUTR’s package, while larger, simplifies heat sinking and may require fewer external components for protection. The enable pin on the TCR2EF33 allows firmware control of power states, which can reduce system power but adds a control line to manage.
Cost-wise, the smaller package and lower complexity of the TCR2EF33 might reduce BOM cost, but this depends heavily on volume and supply chain considerations. The L78L33ABUTR’s wider input range and protection features may justify its higher cost in applications where robustness is critical.
Use-case fit
Choose TCR2EF33,LM(CT) when:
- Designing battery-powered or low-power portable devices where quiescent current must be minimized to extend battery life.
- Operating from a regulated 3.3 V or 5 V rail with limited voltage overhead, needing low dropout to maximize efficiency.
- Firmware-controlled power sequencing is required via an enable pin.
- Maximum load current up to 200 mA is needed in a compact, low-profile surface-mount package.
- High PSRR at audio or low-frequency switching noise (1 kHz) is necessary, such as in sensitive analog front-ends.
Choose L78L33ABUTR when:
- Input voltage can vary widely, up to 30 V, such as in automotive, industrial, or unregulated power supply environments.
- Operating temperature ranges up to 125°C are required for harsh environments.
- Protection against over-temperature, short circuit, and over-current is critical for system reliability.
- Maximum load current is under 100 mA and quiescent current draw is less critical.
- Thermal dissipation capacity is important, and the larger SOT-89-3 package can be accommodated on the PCB.
Drop-in compatibility
The TCR2EF33,LM(CT) comes in an SC-74A (SOT-753) package, while the L78L33ABUTR uses a TO-243AA (SOT-89-3) package. These are not pin-compatible or footprint-compatible. Substituting one for the other will require PCB layout changes and possibly circuit adjustments (e.g., enable pin handling for TCR2EF33). Pin functions and control features differ, particularly due to the enable input on TCR2EF33 and the lack thereof on L78L33ABUTR. Thermal considerations and input voltage requirements must also be reevaluated when swapping parts.
Alternatives to consider
- MIC5205-3.3YC5-TR (Microchip): Low dropout regulator with 150 mA current capability and low quiescent current, suitable for portable devices.
- TLV70433DCKR (Texas Instruments): 3.3 V low-dropout regulator with enable pin and up to 300 mA output, balancing higher current with low power.
- LM1117-3.3 (Texas Instruments): Popular fixed 3.3 V linear regulator supporting up to 800 mA output with higher dropout, useful when higher current is needed and input voltage is sufficient.