The LM2991 is a low dropout adjustable negative regulator with a output voltage range between −3 V to −24 V. The LM2991 provides up to 1 A of load current and features a ON /OFF pin for remote shutdown capability.
The LM2991 uses new circuit design techniques to provide a low dropout voltage, low quiescent current and low temperature coefficient precision reference. The dropout voltage at 1-A load current is typically 0.6 V and an ensured worst-case maximum of 1 V over the entire operating temperature range. The quiescent current is typically 1 mA with a 1-A load current and an input-output voltage differential greater than 3 V. A unique circuit design of the internal bias supply limits the quiescent current to only 9 mA (typical) when the regulator is in the dropout mode (VOUT − VIN ≤ 3 V).
The LM2991 is short-circuit proof, and thermal shutdown includes hysteresis to enhance the reliability of the device when inadvertently overloaded for extended periods. The LM2991 is available in 5-lead TO-220 and DDPAK/TO-263 packages and is rated for operation over the automotive temperature range of −40°C to +125°C. Mil-Aero versions are also available.
| Output options | Adjustable Output |
| Iout (max) (A) | 1 |
| Vin (max) (V) | 0.3 |
| Vin (min) (V) | -26 |
| Vout (max) (V) | -3 |
| Vout (min) (V) | -24 |
| Noise (µVrms) | 200 |
| Iq (typ) (mA) | 0.7 |
| Thermal resistance θJA (°C/W) | 28 |
| Rating | Catalog |
| Load capacitance (min) (µF) | 1 |
| Regulated outputs (#) | 1 |
| Features | Enable |
| Accuracy (%) | 5 |
| PSRR at 100 KHz (dB) | 22 |
| Dropout voltage (Vdo) (typ) (mV) | 600 |
| Operating temperature range (°C) | -40 to 125 |
| TO-220 (KC) | 5 | 45.212 mm² 10.16 x 4.45 |
| TO-220 (NDH) | 5 | 86.0552 mm² 10.16 x 8.47 |
| TO-263 (KTT) | 5 | 154.8384 mm² 10.16 x 15.24 |