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User's Guide
SLUUAA7A–July 2013–Revised August 2014
User's Guide for bq25570 Battery Charger Evaluation
Module for Energy Harvesting
This user’s guide describes the bq25570 evaluation module (EVM), how to perform a stand-alone
evaluation and how to allow the EVM to interface with the system and host. The boost charger output is
configured to deliver up to 4.2-V maximum voltage to its output, VSTOR, using external resistors. This
voltage will be applied to the storage element as long as the storage element voltage at VBAT is above
the internally programmed undervoltage of 2.0 V. The integrated buck converter provides up to 1.8 V and
100 mA at VOUT. The VBAT_OK indicator toggles high when VSTOR ramps up to 3.0 V and toggles low
when VSTOR ramps down to 2.8 V.
Contents
1 Introduction ................................................................................................................... 2
1.1 EVM Features....................................................................................................... 2
1.2 General Description ................................................................................................ 2
1.3 Design and Evaluation Considerations .......................................................................... 3
1.4 EVM Schematic..................................................................................................... 4
1.5 EVM I/O Connections .............................................................................................. 5
2 EVM Performance Specification Summary............................................................................... 7
3 Test and Measurment Summary........................................................................................... 7
3.1 Test Setups and Results........................................................................................... 8
4 Bill of Materials and Board Layout ....................................................................................... 17
4.1 Bill of Materials .................................................................................................... 17
4.2 EVM Board Layout................................................................................................ 18
5 PCB Layout Guideline ..................................................................................................... 20
List of Figures
1 EVM Schematic.............................................................................................................. 4
2 Test Setup for Measuring Boost Charger Efficiency .................................................................... 9
3 Charger Efficiency versus Input Voltage.................................................................................. 9
4 Charger Efficiency versus Input Current ................................................................................ 10
5 Test Setup for Measuring Buck Converter Efficiency ................................................................. 11
6 Buck Converter Efficiency versus Output Current .................................................................... 11
7 Test Setup for Performing Load Transient on Buck Output .......................................................... 12
8 50-mA Load Transient on V
OUT
........................................................................................... 12
9 Charger Operational Waveforms During 50-mA Load Transient .................................................... 13
10 Buck Operational Waveforms During 50-mA Load Transient ........................................................ 14
11 Test Setup for Charging a Super Capacitor from Buck Output ...................................................... 15
12 Charging a Super Cap from V
OUT
........................................................................................ 15
13 EVM PCB Top Assembly.................................................................................................. 18
14 EVM PCB Top Layer ...................................................................................................... 18
15 EVM PCB Bottom Layer................................................................................................... 19
List of Tables
1 I/O Connections and Configuration for Evaluation of bq25570 EVM ................................................. 5
2 Bill of Materials ............................................................................................................. 17
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SLUUAA7A–July 2013–Revised August 2014 User's Guide for bq25570 Battery Charger Evaluation Module for Energy
Harvesting
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