LGS5145

Part: LGS5145 — Legend-Si

Type: Asynchronous Buck Converter (step-down DC/DC regulator) with SKIP mode

Description: 4.5–55 V input, 1 A asynchronous buck converter with integrated 600 mΩ high-side MOSFET, 1.2 MHz fixed switching frequency, up to 90% efficiency and light-load SKIP mode.

Operating Conditions:

• Supply voltage: 5–55 V recommended input range (Table 3); features list 4.5–55 V
• Operating temperature: -40 to 105 °C (operating temperature in the absolute maximum table; the text also states a guaranteed junction range of -40 to 105 °C, while the electrical characteristics are specified for TJ of -40 to 125 °C)
• Switching frequency: 1.2 MHz fixed
• Feedback reference: 0.812 V typical

Absolute Maximum Ratings:

• Max supply voltage: VIN, SW, EN pins to GND -0.3 to 60 V
• Storage temperature: -65 to 150 °C
• BST pin: -0.3 V to SW+6 V; FB pin: -0.3 to 6 V
• ESD: ±3 kV HBM, ±1 kV CDM, ±500 V MM

Key Specs:

• Quiescent current: 150 μA typical (no load, VIN = 12 V)
• Shutdown current: 4 μA typical (EN = 0, VIN = 12 V)
• UVLO: 4.2 V rising / 3.5 V falling (typical)
• High-side RDS(ON): 600 mΩ typical
• Feedback voltage VFB: 0.812 V typical
• Switching frequency: 1.2 MHz typical; 300 kHz foldback frequency (FB = 0.1 V)
• Maximum duty cycle: 94% typical (90% minimum)
• Soft-start time: 2.4 ms typical
• Thermal shutdown: 150 °C rising, 130 °C falling
• θJA: 173 °C/W

Features:

• SKIP mode for high light-load efficiency
• Internal compensation
• Cycle-by-cycle overcurrent protection
• Output short-circuit protection with frequency foldback
• Thermal shutdown and input UVLO
• Soft-start supporting large capacitive loads
• At least 1000 mA continuous output current
• ESD protection on all pins to 3000 V HBM

Applications:

• 42 V automotive power bus
• High-voltage step-down regulation

Package:

• SOT23-6 (6-pin, 0.95 mm pin pitch)

Figure 5.a Typical application topology for DC-DC buck mode