MCP2210 datasheet(6/82 Pages) MICROCHIP

6 / 82 page

MCP2210

DS22288A-page 6

 2011 Microchip Technology Inc.

In order to meet the inrush current requirements of the

USB 2.0 specifications, the total effective capacitance

appearing across VBUS and ground must be no more

than 10 µF. If it is more than 10 µF, some kind of inrush

limiting is required. For more details on Inrush Current

Limiting, see the current Universal Serial Bus Specifi-

cation.

According to the USB 2.0 specification, all USB devices

must also support a Low-Power Suspend mode. In the

USB Suspend mode, devices must consume no more

than 500 µA (or 2.5 mA for high powered devices that

are remote wake-up capable) from the 5V VBUS line of

the USB cable.

The host signals the USB device to enter Suspend

mode by stopping all USB traffic to that device for more

than 3 ms.

The USB bus provides a 5V voltage. However, the USB

transceiver requires 3.3V for the signaling (on D+ and

D- lines).

During USB Suspend mode, the D+ or D- pull-up resis-

tor must remain active, which will consume some of the

allowed suspend current budget (500 µA/2.5 mA).

The VUSB pin is required to have an external bypass

capacitor. It is recommended that the capacitor be a

ceramic cap, between 0.22 and 0.47 µF.

Figure 1-3 shows a circuit where the MCP2210 internal

LDO is used to provide 3.3V to the USB transceiver.

The voltage on the VDD affects the voltage levels onto

the GP and SPI module pins (GP8-GP0, MOSI, MISO

and SCK). With VDD at 5V, these pins will have a logic

‘1’ of 5V with the variations specified in Section 4.1

“DC Characteristics”.

FIGURE 1-3:

TYPICAL POWER SUPPLY

OPTION USING THE 5V

PROVIDED BY THE USB

1.5.2.3

3.3V – Self Powered

Typically, many embedded applications are using 3.3V

or lower power supplies. When such an option is avail-

able in the target system, MCP2210 can be powered

up (VDD) from the existing power supply rail. The typi-

cal connections for MCP2210 powered from 3.3V rail

are shown in Figure 1-4.

In this example MCP2210 has both VDD and VUSB lines

tied to the 3.3V rail. These tied connections disable the

internal USB transceiver LDO of the MCP2210 to

regulate the power supply on VUSB pin. Another

consequence is that the ‘1’ logical level on the GP and

SPI pins will be at the 3.3V level, in accordance with the

variations

specified

Section 4.1

“DC

Characteristics”.

FIGURE 1-4:

USING AN EXTERNALLY

PROVIDED 3.3V POWER

SUPPLY

LDO

3.3V

USB

Transceiver

D+

VDD

VUSB

D-

OUT

5V (USB Bus)

or external

power supply

LDO

3.3V

D+

VDD

VUSB

D-

OUT

5V (USB Bus)

or external

power supply

External

USB

Transceiver

3.3V

LDO

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