USB-C Charger Design Requires PD or CC controller?

Kaveh Mohammad

I have designed a battery charger based on BQ25170DSGR and want to supply this chip with 5V, 50 mA max to operate.

The interface with outside is a USB-C and VBUS is supposed to provide 5V DC to BQ chip.

Do I need a USB-C controller between USB-C port and BQ chip? Right now I have directly connected VBUS to VIN of BQ chip and when I connect it to a (5V,2A and 9V,1.67A) of mine, I get 5V on the bus even without a USB-C controller. So maybe I do not need a controller?

over 3 years ago

0 Kaveh Mohammad over 3 years ago

Intellectual 585 points

This is how the design looks like right now.

+1 Bob Ma over 3 years ago in reply to Kaveh Mohammad

TI__Expert 8980 points

Hi, Kaveh,

The Type-C PD default VBUS voltage is 5V. If there is no type-C/PD controller from sink side, then source will output 5V VBUS by default when it detects device attached, other voltage level need extra handshake between controller from sink and source.

So for your application, no controller is needed. But to let source detect the attachment you need to connect 5.1k from each CC pin to GND. In your schematic I don't see the pull down resistor, there not supposed to have 5V output. However you got the 5V on VBUS, maybe the pull down resistor is connected somewhere.

Bob

0 Kaveh Mohammad over 3 years ago in reply to Bob Ma

Intellectual 585 points

Thanks Bob. Can you confirm if I connect my charger will also work with a DRP device if I add pull down resistor. Please check the reply from another TI expert in below thread:

TUSB320: USB-C Charger Design based on TUSB320 - Interface forum - Interface - TI E2E support forums

If I add pull down resistors, what type of devices I can connect my charger to, to receive 5V from that device? Would it be only DFP source devices like a typical USB-C charger? Or It receives 5V from a DRP device as well?

+1 Bob Ma over 3 years ago in reply to Kaveh Mohammad

TI__Expert 8980 points

Kaveh,

It can receive 5V from both DFP and DRP as long as pull down resistor is connected on CC pin. As below shows, DRP toggle from Rd and Rp, once device connected, DRP CC toggle to Rp, it will stop toggle and behave as source and provide 5V.