UG-108
Rev 1.0, 14-Oct-2018
ACT4921EVK1-301 User’s Guide
Description
This document describes the characteristic and operation of the Active Semi ACT4921EVK1-301 evaluation kit
(EVK). It provides setup and operation instructions, schematic, layout, BOM, and test data. This EVK
demonstrates the ACT4921QI301 eFuse power management IC. Other ACT4921QIxxx options can be
evaluated on this EVK by replacing the IC and any other necessary components.
Features
The EVK can be used as a standalone board if desired. However, to access the internal registers and to take
full advantage of the IC’s capability, the user must connect the EVK kit to a PC with Active Semi’s USB-TO-I2C
interface dongle and use the GUI software. The EVK provides full access to the ICs register settings for things
like fault thresholds and responses, storage voltage setting, startup delays, IC status, and more. This gives the
user the flexibility to configure the EVK to match their real world system. Note that the ACT4921QI301 is
specifically configured for the ACT4921QI301 IC.
Figure 1 – EVK Picture
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Setup
Required Equipment
ACT4921EVK1-301.
USB-TO-I2C Dongle.
Power supply – 2.6V-7V @ 3A for full power operation.
Oscilloscope – >100MHz, >4 channels
Loads – Electronic or resistive. 3A minimum current capability.
Digital Multi-meters (DMM).
Windows compatible computer with spare USB port.
EVK Setup
E-Load
EVK
Power supply
PC
USB dongle
Figure 2 – EVK Setup
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Hardware Setup
1. If using I2C, ensure that a shorting jumper is placed across J6 to provide a pullup voltage.
2. Connect a power supply to J1.
3. Connect an appropriate load to J3.
GUI Setup (optional)
1. Refer to the end of this document for detailed instructions to install the ACT4921 GUI.
2. Connect the USB-TO-I2C dongle to the computer via a USB cable.
3. Connect the USB-TO-I2C dongle to the EVK J6 connector. Refer to Figure 3 to ensure the correct
polarity of the connection. As a guide, use the “Active-Semi” logo on the top of the dongle so the black
wire is connected toward the lower left corner of the Dongle.
Figure 3 – USB-TO-I2C Dongle Connection
EVK Design Parameters
The ACT4921EVK1-301 is designed for a 3.3V input voltage. The maximum operating voltage is determined
by the IC’s maximum input voltage rating. The minimum operating voltages are determined by the buck
converters’ minimum input voltage and by the LDOs’ dropout voltages. Maximum currents are determined by
the IC’s CMI settings, which can be changed via I2C after startup.
Table 1. EVK Design Parameters
Parameter
VIN
I
OUT
I
CL
V
STR
VBuck
Description
eFuse input voltage
Load current
eFuse current limit
Storage voltage
Buck output voltage in supplement mode
Softstart time
Supplement mode holdup time
Min
2.9
Typ
3.3
3
4
28
3.3
5
40
Max
3.7
Unit
V
A
A
V
V
ms
ms
T
softstart
T
holdup
Note: When testing holdup time, IOUT=3A in supplement mode.
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Jumpers and Connectors
J1 – Input voltage to the EVK.
J2 – Additional storage capacitor connector .This connector allows additional storage capacitors to be easily
added for evaluation.
J3 – Output power from the EVK. This is the system load.
J4 – EN pin is internally pulled high by the ACT4921. The eFuse works normally when this pin is pulled high.
Installing a shorting jumper on J4 pulls EN low and disables the eFuse.
J5 – ENB pin is internally pulled high by the ACT4921. The boost circuitry works normally when this pin is
pulled high. Installing a shorting jumper on J5 pulls ENB low and disables the boost.
J6 – I2C connector. Connect to the Active Semi USB-TO-GPIO dongle or to any other I2C communication
device.
J7 – Status Indicator connector. This connector provides easy access to the nIRQ, PG_VO, PLI, and PG_STR
signals.
EVK Operation
Turn on
The EVK is preconfigured and ready to use. Apply the 3.3V input voltage and the EVK automatically powers up,
charges the storage capacitors, and delivers power to the load. No modifications are needed to start evaluating
the ACT4921’s many functions such as supplement mode, current limiting, etc.
Modifications
The EVK is designed to allow the user to immediately start evaluating the ACT4921 functionality. After the user
becomes familiar with the EVK functionality and has verified that they can reproduce the performance data, they
can easily modify the EVK to match their specific system level requirements. Refer to the ACT4921 datasheet
for detailed design equations.
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ActiveSwitcher
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UG-108
Rev 1.0, 14-Oct-2018
Test Results
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ActiveSwitcher
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