LM25118: equation 41

Kurumi Hasegawa

Part Number: LM25118

Hi team,

Could you help us understand how to calculate equation 41 (below) on the datasheet?

What is Iload(internal) value? I couldn’t find such parameter on the datasheet. Is it load current of internal LDO?
What is Qc buck+boost? Is it MOSFET gate-source capacitance Qgs?
Which VCC current limit does it mean? Is it VCC sourcing current limit (typ 35mA)?

Best regards,

Kurumi

0 Stefan Schauer over 3 years ago

Hi Kurumi-san,

thank you for the good question. I need also to investigate and try to find someone how can answer this.

Please give me a few days to find out.

Best regards,

Stefan

0 Kurumi Hasegawa over 3 years ago in reply to Stefan Schauer

Hi Stefan-san,

Thank you for prompt reply. Please let me know when you find the answer.

Best regards,

Kurumi

+1 Stefan Schauer over 3 years ago in reply to Kurumi Hasegawa

Hi Kurumi-san,

i got some more information:

Q: What is Iload(internal) value? There is no such parameter on the datasheet.
- : The entire part runs off of VCC so Vin bias current is the sae as the internal VCC current. It is spec-ed to be 4.5mA (5.5mA max).
Q: What is Qc buck+boost? Is it MOSFET gate-source capacitance Qgs?
- This should be the total Qg for the buck and boost FETs to account for the total gate charge current.
Q: Which VCC current limit does it mean? Is it VCC sourcing current limit (typ 35mA)? But in this condition Vcc=0V
- This is the VCC pin current limit. It is tested with 0V on VCC to simulate a short and activate the internal current limit circuit.

Best regards,

Stefan

0 Kurumi Hasegawa over 2 years ago in reply to Stefan Schauer

Hi Stefan-san,

Thank you for the information! I understand.

Best regards,

Kurumi

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