Key Specs
| Spec | Value | Condition | Source |
|---|---|---|---|
| Control Features | Enable | Digi-Key | |
| Current Quiescent IQ | 8 µA | Digi-Key | |
| Current Supply (Max) | 30 mA | Digi-Key | |
| Input Voltage (Max) | 16V | Digi-Key | |
| Mounting Type | Surface Mount | Digi-Key | |
| Number Of Regulators | 1 | Digi-Key | |
| Operating Temperature Range | -40°C ~ 125°C | Digi-Key | |
| Output Configuration | Positive | Digi-Key | |
| Output Current (Max) | 500mA | Digi-Key | |
| Output Type | Adjustable | Digi-Key | |
| Output Voltage (Max) | 15.3V | Digi-Key | |
| Output Voltage (Min) | 1.235V | Digi-Key | |
| Package Case | SC-74A, SOT-753 | Digi-Key | |
| Protection Features | Over Current, Over Temperature, Reverse Polarity | Digi-Key | |
| Psrr | - | Digi-Key | |
| Supplier Device Package | SOT-23-5 | Digi-Key | |
| Voltage Dropout (Max) | 0.7V @ 500mA | Digi-Key |
When To Use
-
12V automotive accessory → 5V @ 0.5A: The 16V maximum input rating with reverse polarity protection suits typical 12V automotive systems with load-dump transients. Using a generic LDO regulator without reverse polarity protection risks immediate device destruction and potential board damage during miswiring.
-
Battery-powered industrial sensor → 3.3V @ 100mA: The ultra-low 8 µA quiescent current minimizes battery drain during sleep modes, extending operational life. Switching regulators in this class often introduce switching noise that can compromise sensitive analog front-ends, while this part’s linear architecture avoids that failure mode.
-
Embedded control rail → adjustable 1.235–15.3V @ 0.5A: The adjustable output voltage with a dropout voltage of only 0.7V at full load allows tight voltage regulation from a variety of input rails up to 16V. Switching regulators or fixed-voltage LDOs without this flexibility can cause thermal runaway if forced to drop large voltages at high current.
When Not To Use
-
Powering 3A motor driver from 12V rail: The 500mA maximum output current rating is too low, risking thermal shutdown or device failure. Use a multi-phase buck controller to handle higher currents with proper thermal distribution.
-
Battery-powered sensor requiring sub-1µA sleep current: The 8 µA quiescent current is too high for ultra-low power applications where battery life in years is critical. Use a low-IQ PFM buck regulator optimized for µA or nA sleep currents.
-
3.3V output from 3.6V Li-ion with noise-sensitive RF front-end: The 0.7V dropout at full load exceeds the input-output differential, and the linear regulator noise is not optimized for RF. Use an LDO regulator designed for ultra-low dropout and low noise at minimal input-output differential.
Application Notes
-
The Enable pin requires a clean logic-level signal; noise or slow slew on this pin can cause erratic startup or partial enable states. Use a dedicated GPIO or supervisor output.
-
The package (SOT-23-5 / SC-74A) has exposed thermal pad connected internally to ground; ensure proper PCB thermal vias and copper area for heat dissipation to avoid thermal throttling despite the modest 500mA rating.
-
The output voltage is set by an external resistor divider tied to the Adjust pin; minimize trace length and use a low-noise layout near this pin to prevent output voltage drift from coupling or interference.
-
The device includes reverse polarity protection internally, but external diode placement is recommended on input rails with inductive loads to protect against negative transients.
-
Avoid placing noise-sensitive analog components near the input or output bypass capacitors, as ESR and ESL can introduce ripple and affect stability even though this is a linear device.
Design Equations
Output voltage: Vout = 1.24V × (1 + R2/R1)
R1 is typically 1.21kΩ–10kΩ (1% tolerance). Solve for R2: R2 = R1 × (Vout/1.24 - 1). Example: for 5V with R1=1.21kΩ → R2 ≈ 3.74kΩ (use 3.74kΩ 1%).
Gotchas
-
[Output voltage drift with high impedance resistor divider]: Using very high-value resistors (>1MΩ) on the Adjust pin can cause output voltage drift due to leakage currents and noise pickup. This results in unstable or shifted output voltage under varying temperature or humidity. Fix by using resistor values in the 10kΩ–100kΩ range and routing traces away from noisy signals.
-
[Thermal derating above 85°C ambient]: The datasheet’s maximum operating temperature is 125°C, but continuous operation above ~85°C ambient with full 500mA load will cause thermal shutdown due to package limitations. This failure manifests as intermittent output dropouts and increased junction temperature on thermal imaging. Fix with increased PCB copper area, forced airflow, or derating load current at elevated temperatures.
-
[Enable pin floating during power-up]: Leaving the Enable pin unconnected or floating causes unpredictable startup behavior—device may oscillate between enabled and disabled states, causing output voltage ripple or no output. Fix by connecting the Enable pin directly to logic high or a well-defined supervisor output.
-
[Capacitor ESR affecting transient response]: Using ceramic capacitors with very low ESR on the output can cause high-frequency ringing or oscillations due to regulator control loop interaction. This presents as output voltage spikes on load transients. Fix by adding a small ESR polymer or tantalum capacitor in parallel or selecting low-ESR capacitors specified for LDO stability.