Component Comparison: TCR2EF33,LM(CT) vs UA78L05ACDR
Quick verdict
For low-voltage, low-current regulation (3.3 V output, up to 200 mA), especially in battery-powered or low-noise applications, the Toshiba TCR2EF33,LM(CT) is the superior choice due to its low dropout (0.2 V @ 150 mA) and low quiescent current (60 µA). For higher input voltage applications requiring 5 V output with robust protection and wider operating temperature (up to 125°C), the Texas Instruments UA78L05ACDR is preferable despite its higher dropout (1.7 V @ 40 mA) and higher quiescent current (not specified), particularly where reliability and fault tolerance are priorities.
Spec comparison table
| Spec | TCR2EF33,LM(CT) | UA78L05ACDR | Notes |
|---|---|---|---|
| Control Features | Enable | None | TCR2EF33 offers enable pin for power gating, useful for power sequencing and standby. |
| Maximum Input Voltage | 5.5 V | 20 V | UA78L05ACDR tolerates much higher input voltages, better for unregulated or noisy rails. |
| Mounting Type | Surface Mount | Surface Mount | Both are SMT; no clear advantage. |
| Number of Regulators | 1 | 1 | Equivalent. |
| Operating Temperature Range | -40°C to 85°C | 0°C to 125°C | UA78L05ACDR supports extended industrial temperature range, better for harsh environments. |
| Output Configuration | Positive | Positive | Equivalent. |
| Maximum Output Current | 200 mA | 100 mA | TCR2EF33 supports double the current, enabling higher load capability. |
| Output Type | Fixed (3.3 V) | Fixed (5 V) | Different fixed voltages; design choice depends on system voltage requirements. |
| Output Voltage Range | 3.3 V (fixed) | 5 V (fixed) | Output voltages differ; not directly interchangeable. |
| Package/Case | SC-74A (SOT-753) | 8-SOIC (3.9 mm width) | UA78L05ACDR’s 8-SOIC is larger, potentially easier to handle and dissipate heat. |
| Protection Features | Over Current | Over Current, Over Temp, Reverse Polarity, Short Circuit | UA78L05ACDR offers more comprehensive protection, improving system robustness. |
| PSRR (Power Supply Rejection Ratio) | 73 dB @ 1 kHz | 49 dB @ 120 Hz | TCR2EF33 has superior PSRR at 1 kHz, beneficial for noise-sensitive analog circuits. |
| Maximum Dropout Voltage | 0.2 V @ 150 mA | 1.7 V @ 40 mA | TCR2EF33 dropout is significantly lower, improving efficiency and battery life. |
| Quiescent Current (Iq) | 60 µA | Not specified | Low quiescent current of TCR2EF33 favors low-power designs; UA78L05ACDR data missing. |
Design trade-offs
The TCR2EF33,LM(CT) excels in low-voltage, low-dropout regulation scenarios. Its 0.2 V dropout at 150 mA means it can regulate close to the input voltage, which is critical in battery-powered or low-voltage rail designs (e.g., 3.3 V from a 3.7 V Li-ion cell). The low quiescent current (60 µA) reduces system standby power, beneficial for portable or energy-sensitive applications. The inclusion of an enable pin also allows firmware-controlled power gating, useful for dynamic power management.
Conversely, the UA78L05ACDR supports a much wider input voltage range (up to 20 V), making it suitable for systems with unregulated or noisy inputs, such as automotive or industrial supplies. However, its dropout voltage is substantially higher (1.7 V @ 40 mA), which restricts efficiency and usable headroom, especially in low-voltage systems. The maximum output current is limited to 100 mA, half that of the Toshiba device, which constrains its application in higher load scenarios.
Thermal considerations differ significantly. The UA78L05ACDR’s 8-SOIC package is larger and offers better thermal dissipation compared to the smaller SC-74A (SOT-753) package of the TCR2EF33. This, combined with its extended temperature rating (up to 125°C), makes it more suitable for harsh environments or higher ambient temperatures. However, the higher dropout voltage means more power is dissipated as heat under load, requiring careful thermal management.
Protection features also diverge. The UA78L05ACDR includes over-temperature, reverse polarity, and short-circuit protection, enhancing robustness in demanding or less controlled environments. The TCR2EF33 only lists over-current protection, so it may require additional external circuitry for fault tolerance.
From a layout perspective, the smaller SC-74A package of the TCR2EF33 is beneficial for space-constrained designs but demands careful PCB thermal design due to limited heat dissipation area. The UA78L05ACDR’s larger footprint eases handling and heat sinking but consumes more PCB real estate.
Cost at volume is not provided here, but typically, devices with additional protection and extended temperature range (UA78L05ACDR) command a price premium. The simpler, low-dropout TCR2EF33 is likely more cost-effective in consumer or portable applications.
Use-case fit
Choose TCR2EF33,LM(CT) when…
- Designing battery-powered or portable devices requiring 3.3 V rail with tight dropout voltage constraints.
- Low quiescent current is critical to maximize battery life (e.g., IoT sensors, wearable electronics).
- Firmware-controlled power gating is needed via the enable pin for power sequencing or standby modes.
- Noise-sensitive analog or RF circuits require high PSRR at audio and low kHz frequencies.
- PCB space is limited and a small, low-profile package is preferred.
Choose UA78L05ACDR when…
- Input voltage can be as high as 20 V, such as in automotive or industrial applications.
- System requires 5 V fixed output for legacy or standard logic supplies.
- Extended operating temperature range up to 125°C is necessary for harsh or elevated temperature environments.
- Robust protection features (over-temperature, reverse polarity, short circuit) are a design requirement to improve system reliability.
- Thermal dissipation is a concern and a larger package (8-SOIC) can be accommodated for better heat spreading.
Drop-in compatibility
These two parts are not pin- or footprint-compatible. The TCR2EF33 comes in a SC-74A (SOT-753) package, which is significantly smaller and has a different pinout than the UA78L05ACDR in an 8-SOIC package. Additionally, the output voltages differ (3.3 V vs 5 V fixed), so they are not functionally interchangeable without redesigning the PCB and adjusting the downstream system. No direct drop-in substitution is possible.
Alternatives to consider
- MIC5205-3.3YM5-TR (Microchip): Low dropout regulator with 150 mA current capability and low quiescent current aimed at portable devices.
- LM1117-5.0 (Texas Instruments): 800 mA fixed 5 V LDO with moderate dropout, popular for higher current 5 V rails in industrial applications.
- NCP1117 (ON Semiconductor): General-purpose 1 A LDO with fixed voltages and good thermal performance, suitable for medium-power applications.