1 Features

• Two-phase, Synchronous Series Capacitor Buck Converter
• Automatic Current Balancing Between Phases
• 2-MHz to 5-MHz Per Phase Switching Frequency
• 14-ns Minimum On-Time
• 0.51-V to 2-V Output Voltage Range with ±0.5% Feedback Reference Voltage
• Input Overvoltage Lockout for 17-V Surge Protection
• Adjustable Current Limit with Auto Restart (Hiccup)
• Synchronizes to an External Clock
• Fixed Frequency in Steady State
• Adaptive On-Time Control
• Internal Feedback Loop Compensation
• Internal Gate Drive LDO with External Supply Option
• EN Pin Allowing for Adjustable Input UVLO
• Selectable Soft-Start Time
• Monotonic Startup with Pre-biased Output
• Output Power Good Indicator (Open Drain)
• Output Overvoltage/Undervoltage Protection

2 Applications

• Telecom, base station, and communications equipment
• Storage, SSD, DDR memory, switches, hubs, routers, and other networking equipment
• Low profile/Backside board mounting (< 2 mm height)

3 Description

The TPS54A20 is a two-phase, synchronous series capacitor buck converter designed for small size, low voltage applications from a 12-V input rail. This topology uniquely merges a switched capacitor circuit with a two phase buck converter. Advantages include automatic current balancing between the inductors, lower switching losses which enable high frequency (HF) operation, and voltage step-down through the series capacitor. Small, low profile inductors used with the TPS54A20 significantly reduce total solution area and height. An adaptive on-time control architecture provides fast transient response and accurate voltage regulation at up to 10-MHz operating frequency. Fixed frequency operation during steady state is maintained through the use of a phase lock loop (PLL) to lock switching signals to a reference oscillator.

1. For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

Efficiency vs Load Current

1.8 V_OUT, 2 MHz per phase, External VG+, 3.2 x 2.5 x 1.2 mm inductors