MAX3349EA Просмотр технического описания (PDF) - Maxim Integrated

Номер в каталоге

Компоненты Описание

производитель

MAX3349EA

USB 2.0 Full-Speed Transceiver with UART Multiplexing Mode

Maxim Integrated 

USB 2.0 Full-Speed Transceiver with UART

Multiplexing Mode

Table 1. Power-Supply Configuration

VBUS(V)

+4.0 to +5.5

+4.0 to +5.5

GND or Unconnected

VTRM(V)

+3.0 to +3.6 Output

+3.0 to +3.6 Output

High Impedance

VL(V)

+1.4 to +2.75

GND or Unconnected

+1.4 to +2.75

VUART(V)

GND, Unconnected, or

+2.7V to +3.3V

GND, Unconnected, or

+2.7V to +3.3V

+2.7V to +3.3V

CONFIGURATION

USB Mode

Disable Mode

UART Mode

Table 2. USB Transmit Truth Table (OE = 0)

INPUTS

VP

VM

D+

0

0

0

0

1

0

1

0

1

1

1

1

OUTPUTS

D-

0

1

0

1

Table 3a. USB Receive Truth Table (OE = 1,

SUS = 0)

INPUTS

D+

D-

0

0

0

1

1

0

1

1

OUTPUTS

VP

VM

RCV

0

0

RCV*

0

1

0

1

0

1

1

1

X

* = Last state.

X = Undefined.

USB Mode

The MAX3349EA is in USB mode when VBUS is greater

than VTH-BUS and the bus detect output (BD) is logic-

high. In USB mode, power for the MAX3349EA is

derived from VBUS, typically provided through the USB

connector. An internal linear regulator generates the

required +3.3V VTRM voltage from VBUS. VTRM powers

the internal USB transceiver circuitry and the D+ enu-

meration resistor. Bypass VTRM to GND with a 1µF

ceramic capacitor as close to the device as possible.

Do not power external circuitry from VTRM.

Disable Mode

Connect VBUS to a system power supply and leave VL

unconnected or connect to ground to enter disable

mode. In disable mode, D+ and D- are high imped-

ance, and withstand external signals up to +5.5V. OE,

SUS, and control signals are ignored.

Table 3b. USB Receive Truth Table (OE = 1,

SUS = 1)

INPUTS

D+

D-

0

0

0

1

1

0

1

1

OUTPUTS

VP

VM

RCV

0

0

0

0

1

0

1

0

0

1

1

0

UART Mode

Connect VL and VUART to system power supplies, and

leave VBUS unconnected or below VTH-BUS to operate

the MAX3349EA in UART mode. The MAX3349EA sup-

ports VUART from +2.7V to +3.3V (see Table 1).

USB Control Signals

OE

OE controls the direction of communication for USB

mode. When OE is logic-low, VP and VM operate as

logic inputs, and D+/D- are outputs. When OE is logic-

high, VP and VM operate as logic outputs, and D+/D-

are inputs. RCV is the output of the differential USB

receiver connected to D+/D-, and is not affected by the

OE logic level.

ENUM

Drive ENUM logic-high to enable the internal 1.5kΩ

pullup resistor from D+ to VTRM. Drive ENUM logic-low

to disable the internal pullup resistor and logically dis-

connect the MAX3349EA from the USB.

SUS

Operate the MAX3349EA in low-power USB suspend

mode by driving SUS logic-high. In suspend mode, the

USB differential receiver is turned off and VBUS con-

sumes 38µA (typ) of supply current. The single-ended

VP and VM receivers remain active to detect a SE0

state on USB bus lines D+ and D-. The USB transmitter

remains enabled in suspend mode to allow transmis-

sion of a remote wake-up on D+ and D-.

______________________________________________________________________________________ 11

Share Link: