MC7912BT - 1A Fixed -12V Negative Voltage Regulator TO-220 | onsemi
料号： MC7912BT ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $0.85 | $0.85 |
| 10 | $0.72 | $7.20 |
| 100 | $0.58 | $58.00 |
| 500 | $0.49 | $245.00 |
| 1,000 | $0.42 | $420.00 |
MC7912BT 概述
A negative linear regulator (also called an LDO when dropout is low, but the 79xx family is generally classified as a standard linear regulator) is a three-terminal device that maintains a constant negative output voltage relative to ground by dissipating the difference between input and output as heat. These parts sit within the broader power management IC hierarchy: linear regulator -> voltage regulator -> power management IC -> semiconductor. The 79xx family uses a bipolar bandgap reference and pass-transistor architecture with internal current limiting, safe-area compensation, and thermal shutdown.
Key features of the MC7912BT include 1.0 A minimum output current, internal short-circuit current limiting, thermal overload protection, and safe-area compensation for the output pass transistor. The TO-220 package provides a tab that serves as the heatsink, allowing the part to dissipate up to the maximum rated power when properly mounted to a PCB copper pad or external heatsink. The MC7900 series is intended for use in post-regulation after a switching converter, local on-card regulation, or as a building block in dual-tracking ±12V or ±15V analog supplies.
Typical applications include op-amp negative-rail supplies, analog signal-conditioning circuits requiring bipolar rails, industrial 24V-bus interface boards, and hobbyist electronics using the classic 78xx/79xx pair. When designing with the MC7912BT, ensure adequate heatsinking because dropout voltage (typically ~2V) multiplied by load current results in continuous power dissipation that must be removed from the tab. Although the device does not require an external capacitor for stability in most configurations, an input bypass capacitor placed close to the part reduces input impedance and improves transient response.
直接替换替代料： MC7912BT ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
MC7912CTG
✅ 直接替换📋 参考替代料（不在目录中）
MC7912BD2TG
✅ 直接替换📋 参考替代料（不在目录中）
MC7912BTG
✅ 直接替换📋 参考替代料（不在目录中）
MC7915BTG
✅ 直接替换📋 参考替代料（不在目录中）
L7912CV
✅ 直接替换📋 参考替代料（不在目录中）
LM7912CT
✅ 直接替换📋 参考替代料（不在目录中）
MC7912BT 最大额定值与电气特性
| Regulator Type | Negative Fixed Linear Regulator |
| Output Polarity | Negative |
| Nominal Output Voltage | -12 V |
| Output Voltage Tolerance | ±4% |
| 最大输出电流 | 1.0 A |
| Dropout Voltage (typical) | 2.0 V at 1 A |
| 工作结温 | 0°C to +125°C |
| Package Type | TO-220 (3+Tab), 3-pin through-hole |
| 安装方式 | Through-hole (THT) |
| Internal Protection | Current limiting, thermal shutdown, safe-area compensation |
| Series | MC7900 |
| RoHS 状态 | Compliant (Pb-free suffix 'T' suffix) |
| Lead-Free | Yes (T suffix indicates Pb-free) |
MC7912BT 引脚配置
| 引脚 1 | INPUT — Unregulated negative input voltage (most negative) |
| 引脚 2 | GND — Ground reference; electrically tied to the metal tab |
| 引脚 3 | OUTPUT — Regulated -12 V output |
| 引脚 TAB | TAB (GND) — Metal tab internally connected to GND; used for heatsinking |
典型应用
MC7912BT 适用于 6 应用s: Op-Amp Negative Rail Supply, Bipolar ±12V Analog Power Supply, RS-232 Communication Interface Power, Industrial 24V Bus Interface Board, Audio Amplifier Pre-Regulator, Bench Power Supply Bipolar Output.
Op-Amp Negative Rail Supply
The MC7912BT provides the negative -12V rail for op-amps such as the TL072, NE5532, or LM358 in dual-supply analog circuits. With 1.0 A output current and ±4% tolerance, it can power multiple op-amps and small analog signal chains from a transformer-rectified bipolar source. The internal current limit and thermal shutdown protect against output shorts during prototyping, while the TO-220 tab accepts a clip-on heatsink for sustained loads above ~250 mA.
推荐
Bipolar ±12V Analog Power Supply
The MC7912BT pairs with the complementary MC7812 positive regulator to create a regulated ±12V supply for data-acquisition boards, instrumentation amplifiers, and industrial control interfaces. Using the same TO-220 package, both regulators share identical thermal management practices, allowing a symmetric PCB layout. The MC7912BT's 2.0 V dropout permits operation from a ±15V transformer secondary, while internal safe-area compensation lets the part survive sustained output shorts during bench bring-up.
推荐
RS-232 Communication Interface Power
The MC7912BT supplies the negative -12V rail required by legacy RS-232 line drivers such as the MAX232, MAX3232, and ADM232 transceivers that use charge-pump voltage inversion. While modern RS-232 ICs generate ±10V internally from a single +5V supply, the MC7912BT remains the canonical choice when designers want to bypass the charge pump and feed a clean -12V directly. Its 1 A capability easily handles multiple RS-232 ports sharing one negative rail.
推荐
Industrial 24V Bus Interface Board
The MC7912BT regulates a -24V industrial bus rail down to a clean -12V for sensor excitation and analog front-ends in PLC input modules. With internal thermal shutdown and safe-area compensation, it survives the inductive transients common on factory-floor wiring. The TO-220 package is industry-standard for industrial DIN-rail products, and the part's 0°C to +125°C junction range covers most factory environments without derating.
推荐
Audio Amplifier Pre-Regulator
The MC7912BT serves as a low-noise pre-regulator before an audio power amplifier's negative rail, suppressing ripple from upstream switch-mode supplies. While the part itself is a linear regulator (not an LDO in the strictest sense), its high PSRR at audio-band frequencies and the absence of switching noise make it a clean supply for Class-AB amplifier driver stages. Pairing with the MC7812 yields a bipolar supply for headphone amplifiers and preamp circuits.
推荐
Bench Power Supply Bipolar Output
The MC7912BT is a go-to part for hobbyist and lab bench power supplies that need a fixed -12V output channel paired with a variable positive rail. Its robust TO-220 package tolerates the inevitable wiring mistakes and output shorts common on the workbench, while the internal current limit protects downstream loads. Designers commonly combine the MC7912BT with the MC7812 to provide ±12V fixed outputs alongside adjustable channels built around LM317/LM337.
推荐
推荐产品汇总
工程参考数据： MC7912BT ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | MC7912CTG | MC7912BD2TG | MC7912BTG | MC7915BTG | L7912CV | LM7912CT |
|---|---|---|---|---|---|---|---|
| Brand | onsemi | onsemi | onsemi | onsemi | onsemi | STMicroelectronics | Texas Instruments |
| Package | TO-220 (3+Tab) | TO-220 (3+Tab) - same | TO-263/D²PAK - SMD equivalent footprint class | TO-220 (3+Tab) - same | TO-220 (3+Tab) - same | TO-220 (3+Tab) - same | TO-220 (3+Tab) - same |
| Output Voltage | -12 V | -12 V | -12 V | -12 V | -15 V | -12 V | -12 V |
| Output Current (max) | 1.0 A | 1.0 A | 1.0 A | 1.0 A | 1.0 A | 1.5 A | 1.0 A |
| Output Tolerance | ±4% | ±4% | ±4% | ±4% | ±4% | ±4% | ±4% |
| Dropout Voltage | 2.0 V (typ at 1 A) | 2.0 V | 2.0 V | 2.0 V | 2.0 V | 2.0 V | 2.0 V |
| Thermal Shutdown | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Internal Current Limit | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Lead-Free (RoHS) | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
关键差异点
- Pin-to-pin compatible with the entire MC7900 series family （对比 MC7915BTG)
- Higher output current rating than original 7800/7900 vintage （对比 LM7912CT (vintage TI version))
- Cross-brand interchangeability with major manufacturers （对比 L7912CV (STMicroelectronics))
设计说明
Estimated: at VIN = -18 V, VOUT = -12 V, and 1 A load, the MC7912BT dissipates approximately (18-12)*1 = 6 W continuously. The TO-220 tab must be heatsunk with at least 50 cm² of copper pad area or an external clip-on heatsink (theta_JA ~50 °C/W without heatsink). Without adequate thermal management, the internal thermal shutdown engages at ~125 °C junction, causing output to drop or oscillate under sustained load.
Mount the TO-220 tab vertically through the PCB with the tab bent 90° and secured to a chassis or heatsink for maximum heat transfer. Keep input and output traces short and wide to minimize voltage drop and EMI; the input bypass capacitor (0.1-1 µF) should be placed within 5 mm of the input pin. For multilayer boards, stitch thermal vias under the tab to inner-layer copper pours to spread heat.
Do not confuse the MC7912 pinout with the LM317/LM337 adjustable regulators - the 79xx series has IN-GND-OUT on pins 1-2-3 (looking at the front with the tab down), while the LM337 has ADJ-IN-OUT. Connecting an MC7912 to an LM337 footprint will short the output through the wrong pin and likely destroy the part. Always verify the pinout before powering up a hand-wired prototype.
合规信息
Pb-free designation indicated by 'T' suffix on the part number. RoHS compliance verified by onsemi product markings. Not AEC-Q100 qualified - this part is intended for industrial/consumer applications, not automotive.
