Adjustable switching regulator LM2596

step-downbuck

Overview
The LM2596 series are monolithic integrated circuits that provide all active functions for a step-down (buck) switching regulator. They can drive up to 3 A with accurate line and load regulation. Available in fixed outputs (3.3 V, 5 V, 12 V) and an adjustable output version (1.2 V to 37 V). Designed for low external component count and straightforward switch-mode power supply implementation.

Key features

• 3 A maximum output current
• Input voltage range: 4.5 V to 40 V
• Fixed output options: 3.3 V, 5 V, 12 V; adjustable output 1.2 V–37 V (±4% under specified conditions)
• Requires only four external components (typical design)
• 150 kHz fixed-frequency internal oscillator (permits smaller filter components)
• Enable (TTL shutdown) and low-power standby (typical standby ≈ 80 µA)
• Thermal shutdown and two-stage frequency-reducing current limit for protection
• Good line and load regulation; uses readily available standard inductors

Packages and mechanical
Available in standard 5-pin TO-220 packages (several lead-bend options) and a 5-pin TO-263 surface-mount package. Example package areas: TO-220 (NDH) 86.0552 mm² (10.16 × 8.47), TO-220 (NEB) 46.4312 mm² (10.16 × 4.57), TO-263 (KTT) 154.8384 mm² (10.16 × 15.24).

Parameters (summary)
Topology: Buck
Iout (max): 3 A
Vin (min): 4.5 V
Vin (max): 40 V
Vout (min): 3.3 V (fixed) / 1.2 V (adjustable)
Vout (max): 37 V
Iq (typ): 0.005 A (5 mA); standby typically 80 µA
Duty cycle (max): 100%
Control mode: Voltage mode
Features: Enable, Over Current Protection, Thermal shutdown
Operating temperature range: -40 °C to 125 °C

Additional notes
Standard inductors optimized for LM2596 are available from multiple manufacturers. Design resources include datasheets, evaluation modules (EVMs), PSpice models and WEBENCH Power Designer support to accelerate prototyping and validation.