MAX3349E Просмотр технического описания (PDF) - Maxim Integrated

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MAX3349E

Hi-Speed USB 2.0 Full-Speed Transceiver with UART Multiplexing Mode

Maxim Integrated 

Hi-Speed USB 2.0 Full-Speed Transceiver

with UART Multiplexing Mode

Timing Diagrams (continued)

IP 100%

90%

Ir

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

I

100%

90%

AMPERES

36.8%

10%

0

0 tRL

TIME

tDL

CURRENT WAVEFORM

10%

tR = 0.7ns to 1ns

30ns

t

60ns

Figure 10. Human Body Model Current Waveform

Figure 12. IEC 61000-4-2 Contact Discharge Model Current

Waveform

RC

50MΩ to 100MΩ

CHARGE-CURRENT-

LIMIT RESISTOR

RD

330Ω

DISCHARGE

RESISTANCE

HIGH-

VOLTAGE

DC

SOURCE

Cs

150pF

STORAGE

CAPACITOR

DEVICE

UNDER

TEST

Figure 11. IEC61000-4-2 ESD Contact Discharge Test Model

with a 0.1µF ceramic capacitor as close to the device

as possible.

Operating Modes

The MAX3349E operates in either USB mode or UART

mode, depending on the presence or absence of

VBUS. Bus detect output BD is logic-high when a volt-

age higher than VTH-VBUS is applied to VBUS, and

logic-low otherwise. The MAX3349E operates in USB

mode when BD is logic-high, and UART mode when

BD is logic-low.

USB Mode

In USB mode, the MAX3349E implements a full-speed

(12Mbps) USB interface on D+ and D-, with enumerate

and suspend functions. A differential USB receiver pre-

sents the USB state as a logic-level output RCV

(Table 3a). VP/VM are outputs of single-ended USB

receivers when OE is logic-high, allowing detection of

single-ended 0 (SE0) events. When OE is logic-low, VP

and VM serve as inputs to the USB transmitter. Drive

suspend input SUS logic-high to force the MAX3349E

into a low-power operating mode and disable the differ-

ential USB receiver (Table 3b).

UART Mode

The MAX3349E operates in UART mode when BD is

logic-low (VBUS not present). The Rx signal is the out-

put of a single-ended receiver on D+, and the Tx input

is driven out on D-. Signaling voltage thresholds for D+

and D- are determined by VUART, an externally applied

voltage between +2.7V and +3.3V.

Power-Supply Configurations

VL Logic Supply

In both USB and UART modes, the control interface is

powered from VL. The MAX3349E operates with logic-

side voltage (VL) as low as +1.4V, providing level shift-

ing for lower voltage ASICs and microcontrollers.

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