USB2227/USB2228

DS00002256A-page 14

 2007-2016 Microchip Technology Inc.

Note 1: Hot-insertion capable card connectors are required for all flash media. It is required for SD connector to have

Write Protect switch. This allows the chip to detect MMC card.

2: nMCE is normally asserted except when the 8051 is in standby mode.

3: VDD18 (Pin 106) and VDD18PLL (Pin 101) must have a 10uF +/-20% Low-ESR (equivalent series resis-

tance) <0.1 ohm bypass capacitor to VSSA. These capacitors must be as close to these pins as possible.

4.2

Buffer Type Descriptions

nTEST[1:0]

95

96

I

TEST input:

These signals are used for testing the chip. User should normally

tie them high externally, if the test function is not used.

Digital Power, Grounds and no Connects

VDD18

49

106

1.8v Digital Core Power:

+1.8V Core power

All VDD18 pins must be connected together on the circuit board.

VDD33

3

43

80

100

108

3.3v Power & Voltage Regulator Input:

3.3V Power & Regulator Input.

Pins 100 & 108 supply 3.3V power to the internal 1.8V regulators.

VSS

15

16

47

84

85

97

112

Ground:

Ground Reference

TABLE 4-1:

USB2227/USB2228 BUFFER TYPE DESCRIPTIONS

Buffer

Description

I

Input

IPU

Input with internal weak pull-up resistor.

IPD

Input with internal weak pull-down resistor.

IS

Input with Schmitt trigger

I/O8

Input/Output buffer with 8mA sink and 8mA source.

I/O8PU

Input/Output buffer with 8mA sink and 8mA source, with an

internal weak pull-up resistor.

I/O8PD

Input/Output buffer with 8mA sink and 8mA source, with an

internal weak pull-down resistor.

O8

Output buffer with 8mA sink and 8mA source.

O8PU

Output buffer with 8mA sink and 8mA source, with an internal

weak pull-up resistor.

O8PD

Output buffer with 8mA sink and 8mA source, with an internal

weak pull-down resistor.

ICLKx

XTAL clock input

OCLKx

XTAL clock output

I/O-U

Analog Input/Output Defined in USB specification

AIO

Analog Input/Output

Symbol

128-Pin

VTQFP

Buffer Type

Description