Qorvo ACT43850 User Manual

USER'S GUIDE
ACT43950/43850/43750 EVK User's Guide
Description
The ACT43950 is a constant-current capacitor charger. The ACT43850 is a high-voltage and high-power buck regulator. The
ACT43750 controls a drain switch and provides a negative voltage for an RF PA device. This three-chip combination forms a compact,
complete power supply system for radio frequency (RF) power amplifiers (PAs) that demand fast transient, high-current, pulsed loads.
The three-chip combination can be evaluated with one, two, or three ICs on an EVK. These EVKs are referred to as Combo Boards or
CB. This document describes the characteristics and operation of Qorvo's three-chip ACT43950/43850/43750 Combo Board. It also
describes how to use the Combo Board when it is separated into smaller boards. It provides setup and operation instructions,
schematic, layout, BOM, GUI, and test data. Refer to the section of this document that matches the EVK you are testing.
ACT43X50PCKCB1: This Combo Board contains the ACT43750, ACT43850, and ACT43950 ICs.
ACT43X950PCKCB1: This Combo Board contains ACT43950 ICs.
ACT43850PCKCB1: This Combo Board contains the ACT43750 and ACT43850 ICs.
Functions
The first stage ACT43950 accepts a DC input voltage up to 400V and converts it into a regulated DC constant current to charge bulk
capacitors. The second stage ACT43850 takes up to 150V DC input to generate programmable output voltage from 20V to 65V at up to
20A. The last stage is the ACT43750 which has two main functions. The first is to provide proper turn on sequencing for RFPAs. The
second is to control pulsed drain voltage switching for the RFPA.
Qorvo recommends that the user connect EVK to a PC and use the graphical user interface (GUI) software. The GUI allows the user to
enable/disable devices and program the exact voltage and current for the specific RF PA being tested. AC43950 does not have
registers but can be enabled/disabled by a GPIO from the Dongle when using the ACT43850 GUI. The ACT43850 GUI gives the user
full control over the drain voltage, protection features, and gate voltage. The user can use the ACT43750 GUI to set the Idq bias current
requirement, and the design autonomously finds and stores the optimal gate voltage for the Idq bias current. After the optimal gate bias
voltage is found, the user can then apply an RF signal to test the RF PA functionality.
EVK Contents
The EVK contents vary depending on the configuration shipped.
Figure 1 shows the ACT43X50PCKCB1. The board you are testing will be this full PCB or a subset of this PCB.
The board you are testing should be shipped pre-configured for the user's requirements. If the user modifies the board, Qorvo
recommends they separate the boards and test each section individually before recombining them to perform system-level testing.
Skip to the User's Guide section that matches the board you are testing. This document contains instructions to setup and test the
following combinations.
ACT43950PCKCB1
ACT43850PCKCB1
ACT43X50PCKCB1
APPENDIX
Application Note 1: Safe Operation at High Drain Switching Frequency
March 2024 Rev 1.0 | Subject to change without notice 1 of 52
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