Getting Started

Configuration Description

Vmpp: Maximum Power Point Voltage - Select the appropriate maximum power point based on the characteristics of different solar panels; the amorphous silicon panel included in the kit is set at 70%.

Vsrc: Energy Source Voltage - Voltage of the energy source such as solar panels, kinetic energy batteries, etc. Energy harvesting begins when Vsrc > 400mV and 15uW.

Vbat: Battery Voltage - Voltage of the energy storage device such as supercapacitors, rechargeable batteries, etc.

PRIM: Primary - Primary battery.

Voc: Overcharge Voltage - Typically the maximum voltage that the storage element can accept or the highest voltage desired for charging the energy storage device.

Vcr: Charge Ready Voltage - The minimum voltage required on the storage element before enabling the LDO (Low Dropout Regulator) after starting energy storage.

Vod: Overdischarge Voltage - The minimum voltage that the energy storage device can accept before switching to a primary battery or entering shutdown mode.

The module operates according to the following flowchart:

• When Vsrc > 400mV and 15uW, the module wakes up to start harvesting energy for charging the energy storage device.
• When Vbat > Vcr, the module enters normal mode, and the LDO can start outputting.
• When Vbat > Voc, the module enters overcharge protection mode. The LDO can still output, but the module stops charging capacitors.
• When Vbat ≤ Vod and PRIM is connected, PRIM charges the energy storage device to Vcr. Then, the module enters normal mode, and during this period, the LDO outputs normally.
• When Vbat ≤ Vod and PRIM is not connected, the module enters shutdown mode. The LDO stops outputting after 600ms until Vbat > Vcr.

See the DFM8001 module datasheet for more details on operating modes.

Quick Start

Requirements

• Energy Harvesting Module Evaluation Board x 1
• 0.22F Supercapacitor x 1
• Amorphous silicon photovoltaic panel x 1
• Multimeter/1.8V low-power load

Operational Process:

1. All jumper caps are in default state. Do not adjust jumper cap configurations without full understanding of all settings, as this may risk damage.

   1. SCL_BAT：CAP
   2. L_EN and H_EN：1
   3. VCF[2]：1
   4. The remaining jumper caps are configured as 0

2. Insert the 0.22F super capacitor into the board. Before fully understanding all configurations, use the new 0.22F super capacitor provided in the kit. When using pre-charged capacitors or batteries, ensure the initial voltage of the capacitor is less than Voc.

3. Connect the amorphous silicon photovoltaic panel and ensure the front side of the panel is exposed to light. When connecting, pay attention to the terminals of the evaluation board to be in full contact with the metal part of the PV panel leads, pressing in too much of the wire's insulating jacket may cause connection failure.

4. At this point, the Vbuck voltage will slowly rise to around 2.2V, indicating that the system has started and is beginning to charge the capacitor. If the voltage cannot reach 2.2V and remains low, it suggests either insufficient light or an abnormal connection to the power source, preventing the system from starting.

5. When the voltage of the 0.22F capacitor reaches 2.3V, the LDO activates and begins to supply power output.

Using a 0.22F super capacitor allows for quicker observation of output phenomena. If the energy stored in the 0.22F capacitor is insufficient, consider replacing it with the provided 1.5F capacitor or refer to subsequent chapters in the wiki for more configuration options.

Connection Diagram

Advanced tutorial

• In the advanced tutorial, the following will be demonstrated:
  • Using lithium batteries as energy storage devices
  • Using more efficient solar panels as input sources
  • Controlling LDO output activation using an MCU

Requirements

• Energy harvesting module evaluation board x 1
• Thin-film organic photovoltaic panel x 1
• Lithium battery / other rechargeable battery
• Electrical appliances

Operational Process:

1. To prevent accidental operation, remove the supercapacitor from the board.
2. Adjust the jumper cap positions:
   1. SCL_BAT: BAT
   2. VCF[2]-VCF[0]: 1 1 1, with Voc=4.12V, Vcr=3.67V, Vod=3.6V, Vh=3.3V, VL=1.8V
   3. MPPT[1]-MPPT[0]: 1 0,85%, determined by the parameters of the connected input source.
3. Remove the jumper cap from H_EN, and connect the midpoint of H_EN to a digital output IO of the MCU. This allows the MCU to control whether H_OUT starts output.
4. Ensure the lithium battery voltage is <4.12V before connecting to the BAT terminal.
5. Connect the solar panel.

Connection Diagram

For more advanced applications, please refer to the DFM8001 datasheet.