Analog Devices Inc. LTC7890/1 Synchronous Step-Down Controllers

Analog Devices LTC7890/1 Synchronous Step-Down Controllers are high-performance, dc-to-dc switching regulator controller that drives all N-channel synchronous gallium nitride (GaN) field-effect transistor (FET) power stages from input voltages up to 100V. The LTC7890/1 Controllers are the solution to challenges traditionally faced when using GaN FETs. The devices simplify the application design with no protection diodes or additional external components needed compared to a silicon metal-oxide-semiconductor field-effect transistor (MOSFET) solution.

The ADI LTC7890/1 Synchronous Step-Down Controllers support an internal smart bootstrap switch that prevents overcharging of the BOOST pin to SW pin high-side driver supplies during dead times, protecting the gate of the top GaN FET. Additionally, the LTC7890/1 internally optimizes the gate driver timing on both switching edges to deliver smart near-zero dead times, significantly improving efficiency and allowing for high-frequency operation, even at high input voltages. The user can adjust the dead times alternatively with external resistors for margin or tailor the application.

The gate drive voltage on the LTC7890/1 precisely adjusts from 4V to 5.5V to optimize performance and enable different GaN FETs or even logic-level MOSFETs.

The LTC7890 is available in a 40-lead (6mm × 6mm), side wettable, QFN package, while the LTC7891 has a 28-lead (4mm × 5mm) side wettable, QFN package.

Features

GaN drive technology fully optimized for GaN FETs
4V to 100V Wide V_IN range
0.8V ≤V_OUT ≤60V Wide output voltage range
No catch, clamp, or bootstrap diodes needed
Internal smart bootstrap switches prevent overcharging of high-side driver supplies
Internally optimized, smart near-zero dead times or resistor-adjustable dead times
Split output gate drivers for adjustable turn-on and turn-off driver strengths

Accurate adjustable driver voltage and UVLO
5μA (48 V_IN to 5 V_OUT) Low operating I_Q
Programmable frequency (100kHz to 3MHz)
Phase lockable frequency (100kHz to 3MHz)
Spread spectrum frequency modulation
Packages
- 40-lead (6mm × 6mm), side wettable, QFN package (LTC7890)
- 28-lead (4mm × 5mm) side wettable, QFN package (LTC7891)