LM2903DRG3 - Dual Open-Collector Comparator | Texas Instruments
部品番号: LM2903DRG3 ✓ 生産中LM2903DRG3 概要
A comparator is a differential amplifier whose output is driven to a logic state when one input exceeds the other by more than the input offset voltage. It belongs to the amplifier IC family, sits under the operational amplifier hierarchy, and ultimately falls inside the linear and signal-conditioning IC category. Unlike an op-amp, a comparator has no linear output region and is not intended for open-loop gain; its open-collector output is designed to pull a rail low and to be pulled up externally, which allows it to sink more current than a CMOS push-pull output can.
Key features include a maximum rated supply of up to 38 V, an ESD rating of 2 kV HBM, a low input offset voltage of 0.37 mV and a low input bias current of 3.5 nA, all of which improve threshold accuracy and reduce source loading on the sensed signal. The differential input voltage range is equal to the maximum rated supply voltage at ±38 V, and the common-mode input voltage range includes ground, allowing the device to monitor bipolar signals referenced to 0 V. Outputs are compatible with TTL, MOS and CMOS logic families.
Electrically the device is a bipolar dual differential comparator with an open-collector output stage. The open-collector architecture means the output can be pulled to any supply level the system uses, and a pull-up resistor sets the high level. This is essential in relay-drive, lamp-drive and level-shifting designs where the load requires more current than the IC itself can source.
Typical applications include industrial sensor threshold detection, battery and rail window comparison, overvoltage and undervoltage protection in power supplies, temperature monitoring with thermistors or RTDs, and current-sense comparison in motor drive and inverter control stages.
When designing with the LM2903DRG3, always place the pull-up resistor close to the output pin and check that the total sink current stays within the output rating, because the open-collector transistor, not the internal drive, sets the load capability.
This page consolidates parametric data, drop-in alternatives, comparison tables and practical design notes so engineers can evaluate the LM2903DRG3 against equivalent dual comparators without rebuilding the analysis from scratch.
ドロップイン代替品: LM2903DRG3 — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。
このシリーズのバリエーション
同一シリーズでドロップイン互換のモデル: LM2903DRG3 （同一形状・フットプリント） — 相違点: Package, Operating Temperature Range, Output Type, Comparator Type, Number of Channels.
LM2903DG4
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データシートを見る →LM2903DR
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データシートを見る →LM2903BDR
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LM393BDR
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LM2903BIDR
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データシートを見る →LM393DT
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データシートを見る →LM2903BIDR
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データシートを見る →LM393AD
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データシートを見る →LM2903DRG3 最大定格＆電気的特性
| Comparator Type | Dual Differential Comparator |
| Number of Elements | 2 |
| 出力タイプ | Open-Collector (compatible with TTL, MOS and CMOS) |
| Supply Voltage Range (Single Supply) | 2 V to 36 V |
| Supply Voltage Range (Dual Supply) | ±1 V to ±18 V |
| Maximum Rated Supply Voltage | up to 38 V |
| Input Offset Voltage | 0.37 mV |
| Input Bias Current | 3.5 nA |
| Supply Current per Comparator | 200 µA |
| Response Time | 1 µs |
| ESD Rating (HBM) | 2 kV |
| Differential Input Voltage Range | ±38 V |
| Common-Mode Input Voltage Range | Includes ground |
| 動作温度範囲 | -40 °C to +125 °C |
| パッケージ | 8-SOIC (0.154 in / 3.90 mm width) |
| 実装タイプ | Surface Mount |
| Supplier Packaging | Tape & Reel |
| RoHS ステータス | Compliant |
LM2903DRG3 ピン構成
| ピン 1 | OUT 1 — Open-collector output of comparator channel 1 |
| ピン 2 | IN 1- — Inverting input of comparator channel 1 |
| ピン 3 | IN 1+ — Non-inverting input of comparator channel 1 |
| ピン 4 | GND — Ground / negative supply connection |
| ピン 5 | IN 2+ — Non-inverting input of comparator channel 2 |
| ピン 6 | IN 2- — Inverting input of comparator channel 2 |
| ピン 7 | OUT 2 — Open-collector output of comparator channel 2 |
| ピン 8 | V+ — Positive supply voltage connection |
主な用途
LM2903DRG3 の用途: 6 件s: Industrial Sensor Threshold Detection, Automotive Battery and Rail Monitoring, Power Supply Overvoltage and Undervoltage Protection, Motor Drive and Inverter Current Sensing, Temperature Monitoring with Thermistors and RTDs, Window Comparison and Fan Speed Control.
Industrial Sensor Threshold Detection
The LM2903DRG3 suits industrial sensing front ends where a resistive or active sensor output must be compared against a fixed reference. Its 0.37 mV input offset voltage keeps the switching point tight, and the 3.5 nA input bias current produces negligible error when the sensor sits at high impedance. The comparator is typically wired with the reference on the inverting input and the sensor on the non-inverting input, so the open-collector output goes low when the sensor exceeds the setpoint. Because the common-mode input range includes ground, 4-20 mA loop and 0-10 V signals referenced to 0 V can be monitored without biasing networks. A 10 kΩ pull-up to the local logic rail keeps the sink current well inside the output rating while letting the output drive an isolated relay, a PLC input or a counter stage downstream.
おすすめ
Automotive Battery and Rail Monitoring
In 12 V and 24 V vehicle electrical systems, the LM2903DRG3 can watch the battery rail against over- and under-voltage limits. The wide 2 V to 36 V single-supply range means the device can be powered from the same rail it monitors, and the maximum rating of up to 38 V provides headroom for load-dump transients. Its differential input range of ±38 V lets the comparator evaluate a divided battery voltage without saturating the input stage. The operating temperature range of -40 °C to +125 °C matches vehicle ambient conditions. The open-collector output is the right interface for driving an indicator lamp, a warning relay or an enable line to a downstream regulator, since the sink current is set by the pull-up network rather than by the internal drive stage.
おすすめ
Power Supply Overvoltage and Undervoltage Protection
The LM2903DRG3 is widely used in power supply designs as a crowbar or UVLO trigger. The output saturates close to the logic rail, so driving a thyristor, a series MOSFET gate driver or a load-switch enable is straightforward, and the low output saturation voltage keeps the trigger node clean. With a 1 µs response time, the comparator reacts quickly enough to protect downstream rectifiers and switching devices when a rail exceeds its safe window. The open-collector output also makes fail-safe wiring straightforward: with the pull-up resistor fitted, the output sits high during normal operation and drops low only when a fault condition is detected. Keeping the sensing divider resistors close to the input pins and the pull-up close to the output pin minimises injected noise on a node that switches hard.
おすすめ
Motor Drive and Inverter Current Sensing
In motor drive and inverter modules, shunt amplifier outputs or motor phase voltages must be compared against trip levels before the controller acts. The LM2903DRG3 fits this role because its differential input range equals the maximum rated supply of ±38 V, so a bipolar sense signal around 0 V is handled without clipping, and the common-mode input range includes ground, which is exactly where a shunt output sits. The 1 µs response time complements the fast switching currents typical of a PWM inverter, while the 3.5 nA input bias current keeps the error negligible against the small shunt voltages involved. The open-collector output can trip a hardware fault input on the gate driver or a microcontroller capture comparator input, and the external pull-up resistor allows the trip signal to be referenced to whichever logic rail the controller uses.
おすすめ
Temperature Monitoring with Thermistors and RTDs
Thermistor and RTD chains present very high source impedances, so the comparator input characteristics matter. The LM2903DRG3 input bias current of 3.5 nA keeps the error contribution at a fraction of a millivolt even against a 100 kΩ sensor, and the 0.37 mV offset voltage keeps the trip window narrow over a wide temperature span. The device is placed in the bridge or divider so the reference voltage sits on one input and the sensor node on the other, with the comparator output driving a fan, an alarm or a setpoint relay through its open-collector stage. The wide supply range means the same part works from a 5 V control board or a 24 V machine bus, and the common-mode input range including ground suits sensors that fall below the lower rail during fault conditions.
おすすめ
Window Comparison and Fan Speed Control
The two independent channels of the LM2903DRG3 can be used as the two halves of a window comparator, defining an upper and lower trip point around a slowly moving signal such as a supply rail, a fan tachometer pulse train or a battery level. Each channel compares the signal against its own reference, and both open-collector outputs can be wired to the same pull-up so the combined output indicates an in-window state. This is more economical than two separate single comparators and keeps both thresholds in one package with matched behaviour. Because the open-collector outputs are open, they can also be combined with a diode to build simple hysteresis or OR logic without additional gates, and the external pull-up resistor lets the designer choose the logic level of the combined node.
おすすめ
おすすめ製品の概要
エンジニアリング参考データ: LM2903DRG3 — 比較、設計ガイダンス、コンプライアンス情報。
選定ガイド
代替品との比較
| パラメータ | この製品 | LM2903DG4 | LM2903DR | LM2903BDR | LM393BDR | LM2903 | LM393 | LM2903 | LM393A |
|---|---|---|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | STMicroelectronics | STMicroelectronics | onsemi | onsemi |
| Package | SOIC-8 (8-SOIC, 0.154 in / 3.90 mm width) | SOIC-8 - same footprint | SOIC-8 - same footprint | SOIC-8 - same footprint | SOIC-8 - same footprint | SOIC-8 - same footprint | SOIC-8 - same footprint | SOIC-8 - same footprint | SOIC-8 - same footprint |
| Comparator Type / Channels | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements | Dual differential comparator, 2 elements |
| Output Type | Open-Collector, compatible with TTL, MOS and CMOS | Open-Collector | Open-Collector | Open-Collector | Open-Collector | Open-Collector | Open-Collector | Open-Collector | Open-Collector |
| Supply Voltage Range | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply | 2 V to 36 V single supply; ±1 V to ±18 V dual supply |
主な差別化要因
- Wide supply range with industrial/automotive temperature grading （vs TLV2402ID)
- Common-mode input range includes ground for ground-referenced sensing （vs LM2903 (STMicroelectronics))
- Open-collector output drives loads that CMOS push-pull comparators cannot （vs TLV2402ID)
- Upgradable to the improved B-version in the same footprint （vs LM2903DR)
設計ノート
The open-collector output is not a push-pull output, so it must always have a pull-up resistor to a valid logic rail. Without it the output node floats and the comparator state is undefined. Size the resistor against the sink current limit in the datasheet output characteristics: a 10 kΩ pull-up to 5 V draws about 0.5 mA when the output is low, which is well within the capability of the open-collector transistor and keeps the switching node quiet. Place the pull-up resistor physically close to the output pin to minimise the trace length of the high-impedance node and to reduce susceptibility to induced noise during the output transition.
Keep the two input networks of each channel short and route them away from the supply and output traces. Input bias current of 3.5 nA flowing into a high-impedance sensor node creates a voltage error proportional to source impedance, so long parallel copper runs act as antennae for leakage and injected noise. Place the supply decoupling capacitor close to pin 8 with a short ground return to pin 4, and if the two channels monitor widely separated signals, keep their input routing apart to prevent crosstalk from a fast switching node on one channel into the input of the other.
Estimated: with VIN = 12 V, VOUT = 5 V and a load of 1 A drawn from the open-collector output path through a 10 kΩ pull-up plus an external load, the LM2903DRG3 itself dissipates very little internally because the comparator only sinks current. Using the family figures of 200 µA supply current per comparator at 12 V, the device dissipation is approximately 12 V x 0.4 mA = 4.8 mW, which is negligible in an 8-SOIC package. The real thermal load in such designs comes from the pull-up resistor and any relay coil, so derate those against the SOIC-8 power dissipation capability instead.
The differential input voltage range equals the maximum rated supply of ±38 V, but the input stage is still sensitive to signals that exceed the absolute maximum ratings of the pins. Never let an input exceed the supply rails by more than the permitted margin, and add series input resistors when the source can ring or exceed the rail during transients. Because the common-mode input range includes ground, the comparator can be used as a zero-crossing detector for bipolar signals, but the differential offset of 0.37 mV means a slow ramp produces narrow, noise-sensitive pulses, so add positive feedback as hysteresis when the input slope is low.
コンプライアンス情報
The LM2903DRG3 orderable code is the RoHS-compliant green (G3) tape-and-reel variant of the LM2903 family. REACH, lead-free status beyond RoHS, halogen-free status and conflict-minerals declarations are not stated for this orderable code. The standard LM2903 part is temperature graded for -40 °C to +125 °C rather than AEC-Q100 qualified.
