LM5005: RAMP problem

Zoey Wu

Part Number: LM5005
Other Parts Discussed in Thread: LMR38020

hi team,

my customer find that when the add a pull up resistor of 75kΩ in RAMP to VCC, the Vout can't stay at 24V when they increase the output current. Do u have any advice on the case? thanks!

Vin:48V, Vo:24V, IO=1A

6 months ago

0 Shipeng Cheng 6 months ago

TI__Expert 5220 points

Hi Zoey,

Can you upload the schematic for us? Please let customer measure the waveform of RAMP pin. If the emulated ramp signal exceeds 1.75 V (3.5 A), the present cycle is terminated (cycle-by-cycle current limiting).

By the way, I recommend our new product LMR38020 (80V, 2A) which is easier to use.

Thanks.

BR,

Shipeng

0 Zoey Wu 6 months ago in reply to Shipeng Cheng

TI__Expert 3930 points

Thanks for your reply~

The SCH is as below.

0 Shipeng Cheng 6 months ago in reply to Zoey Wu

TI__Expert 5220 points

Hi Zoey,

The C57 is too small. I recommend 1nF.

And the inductor is too small. It should be at least 68uH.

Power management

Power management forum

LM5005: RAMP problem