The LM2903AL1-SR is presented as a low‑power, wide‑supply‑range dual comparator intended for battery‑sensitive and mixed‑voltage systems. The datasheet lists a recommended supply range starting near +2.5 V and typical quiescent currents around 150 µA per channel. This article pairs published specs with repeatable bench procedures, measured tables, and PCB/integration guidance.
(1 of 6) — Background & Product Overview
What LM2903AL1-SR is
The device is a dual comparator featuring open‑collector outputs and a wide operating voltage window. Open‑collector outputs require external pull‑ups but allow level translation; input tolerance simplifies interfacing to sensors that swing near ground.
- Supply range: ~2.5 V to 36 V
- Typical Iq per channel: ~150 µA
- Input common‑mode: Includes ground
- Output: Open‑collector architecture
(2 of 6) — Key Specs & Electrical Characteristics
| Parameter | Symbol | Condition | Typ/Max | Units |
|---|---|---|---|---|
| Supply Voltage | VCC | Recommended | 2.5 — 36 | V |
| Supply Current | Iq | VCC=5V, per ch | 150 / 300 | µA |
| Input Offset Voltage | VOS | VCC=5V | 2.0 / 7.0 | mV |
| Common-mode Range | VICR | Ta=25°C | 0 to VCC-1.5 | V |
(3 of 6) — Test Setup & Measured Bench Results
Recommended Measurement Procedures
Reproducible measurements require strict fixture settings. Use a low‑inductance supply with 0.1 µF local decoupling and 10× compensated scope probes.
- Propagation Delay: ~1.5–3 µs (VCC=5V, RL=10k)
- Supply Current: ~150–300 µA at 3.3V rail
- Offset Drift: Measured in µV/°C scale over -40 to +85°C
(4 of 6) — Integration & PCB Design Guidelines
Layout Best Practices
Layout practices affect stability and noise immunity. Place decoupling caps within 2–3 mm of the VCC pin and position pull‑up resistors near the output pins to reduce parasitics. Add hysteresis (positive feedback) when input noise causes chatter at the trip point.
(5 of 6) — Competitive Comparison
| Feature | LM2903AL1-SR Class | High-Speed Alternatives |
|---|---|---|
| Supply Range | Wide (Up to 36V) | Narrow (typically 5V) |
| Power Drain | Low (~150 µA) | High (mA range) |
| Speed | Moderate (µs) | Ultrafast (ns) |
(6 of 6) — Troubleshooting & Checklist
- Verify pull‑up resistor is present (Open-collector will not swing high without it).
- Check if input signals stay within the (VCC - 1.5V) common-mode limit.
- Measure VCC ripple; excessive noise can cause false triggering.
Key Summary
- Low Power: Ideal for battery-powered threshold detection.
- Open-Collector: Enables easy level-shifting to various MCU logic levels.
- Validation: Always characterize propagation delay vs. your specific RL/CL load.
Common Questions
What test conditions reveal real propagation delay behavior?
Measure with the intended VCC values and actual pull‑up resistances (4.7k–47k range), use a small capacitive load (few pF), and trigger the scope on the input step.
How should pull‑ups be chosen for interfacing to microcontrollers?
Choose pull‑up voltage matching the MCU input tolerance. Use 10k for low power; use 4.7k or lower where faster rise times are required.
Which specs are most critical for precision threshold detection?
Input offset voltage (VOS) and its temperature drift are primary. Characterize these under your actual supply and temperature range.
Is LM2903AL1-SR suitable for high-speed switching?
No, it has a moderate propagation delay in the microsecond scale. It is designed for robustness and low power rather than sub-100ns timing requirements.
