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Author Topic: FT230X VCCIO current  (Read 1618 times)

r6mf49t2

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FT230X VCCIO current
« on: April 06, 2018, 06:47:05 AM »

I'm developing a battery-powered device. I plan to connect the VCCIO to the battery (2-3V), and connect VCC to the USB (5V). (As described in Chapter 5.6 Variable IO Voltage Supply http://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_UMFT230XA.pdf).
What VCCIO current will be in case when usb is connected and when is not?
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Re: FT230X VCCIO current
« Reply #1 on: April 12, 2018, 04:44:18 PM »

Hello,

The VCC and VCCIO supplies should power on and off together and so should be supplied from the same overall source (even if VCCIO is derived from a regulator, this regulator should have the same source as VCC).

For example, you could
- Power VCC, VCCIO, 3v3out from a 3v3 rail in your device (self powered config)
- Power VCC from USB 5V and power VCCIO from 3v3OUT on the FT230X (bus powered config)
- Power VCC from USB 5V and power VCCIO from a regulator sourced from USB 5V (bus powered config) giving 3v3 or 1v8 VCCIO.

If you use the first option, you can use the VBUS Sense CBUS line to sense USB Vbus through a voltage divider to put the device in a low power suspend state when no USB host is present.

The second and third options will use power from the USB port and so won't use as much battery power. You can feed USB Vbus through a divider into an input line on your MCU and your code can use this signal to tristate it's connections to the RxD and CTS lines of the FT230X (since these are both outputs from the MCU) so that you don't have leakage from the MCU to the FT230X in their idle high state.

Best Regards, FTDI Community


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r6mf49t2

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Re: FT230X VCCIO current
« Reply #2 on: April 16, 2018, 06:33:40 AM »

This contradicts the following document: http://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_UMFT230XA.pdf

Quote
The FT230X can process signals at CMOS/TTL logic levels in the range of 1.8V to 3.3V.
Figure 5.4 shows a configuration where the FT230X is interfaced to a device with IOs operating in the range of 1.8V – 3.3V. The IO ports of this module need to be powered with a voltage level that is equal to the level of the signals it is processing. Since the FT230X’s embedded voltage regulator only outputs 3V3 the IO ports will need to be powered from another power source when operating at voltage levels other than 3.3V.

If power is applied to VCCIO and no power is applied to VCC all Ios will be at an unknown state, this however will not damage the chip.
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Re: FT230X VCCIO current
« Reply #3 on: April 17, 2018, 01:21:50 PM »

Hello,

Please note that our recommendations are not intended to contradict or replace the datasheet, and are intended as additional helpful advice only. The device datasheet still provides the most up to date device information and so you can still refer to the configurations shown there.

By powering your regulator from the same source as VCC, you can avoid the case mentioned whereby the IOs are at unknown states which is advantageous for many use cases.

Best Regards, FTDI Community
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