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# TLV61220: Tuning the output current DC to DC booster

Part Number: TLV61220

Hi TI,

Currently i am using DC to DC booster TLV61220,

Vin is able to reach above 1V, Iin (Input Current) about 100uA (low)., and Vout 3V (based on R1-R2)

is there anyway to tune the output current?

Thank you

• not sure about the question? why do you want to "tune" the output current?

Jasper Li, Boost Solution Application

• In reply to Jasper Li:

hi Jasper Li,

The input of TLV61220 connected with energy harvesting module,

if it doesnt connect to the load, i got the voltage 3V as expected.

the output of TLV61220 drop once i connect it to the load (MCU).

so in this case, i need to increase the current and keep the voltage at 3V.

Thank you.

• In reply to dhana laksana:

could you measure the waveform of VIN and VOUT once connect the load? i'm thinking maybe the input voltage is too low after adding load

Jasper Li, Boost Solution Application

• In reply to Jasper Li:

Jasper Li
could you measure the waveform of VIN and VOUT once connect the load? i'm thinking maybe the input voltage is too low after adding load

Here is the waveform,

i give load 100kohm and the R1=1Mohm R2=200kohm

the yellow = input, blue = output.

if I keep the ratio of R1 and R2 but i decrease the resistor, is there any effect on Output Current or Voltage?

thank you

• In reply to dhana laksana:

the behavior of the waveform is normal.
at the beginning, the input voltage is only 0.6V, so the output ramps to only 2.7V step by step, depending on the power supply capability.
after the input voltage reach 1.6V, the TLV61220 well regulates at VOUT=3V.
Then VIN increase to 4.3V or higher, the VOUT will following VIN. the VOUT is (VIN-0.4V).

As the input could be much higher than setting 3V, it seem you need a BUCK converter instead of boost converter.
change the R1 and R2 doesn't help.

Jasper Li, Boost Solution Application

• In reply to Jasper Li:

Hi Jasper Li,

The Energy Harvesting Module (EH) is placed before DC booster, and There is MCU after DC booster

When i try the EH without DC Booster it seems the voltage is able to increase up to 3V.

If i connect the DC booster and MCU, the Input and Output of DC booster looks like the picture below.

Yellow is the input (After EH) and Blue is the output of DC booster.

Is there any effect of the input capacitor?

Thank you

• In reply to dhana laksana:

the reason is that the source is too weak to start up the boost. from your description "EH can output 3V without boost", why do you add a boost converter? and from my understand, you need to device with MPPT function. however, our boost device don't integrates this feature.

Jasper Li, Boost Solution Application

• In reply to Jasper Li:

the reason i need to use converter because i can tune the output up to from 3 to 5V while the input voltage less than 3V.
• In reply to dhana laksana:

you can connect the EN pin to MCU I/O, and enable the boost when the input voltage is ready.

Jasper Li, Boost Solution Application