MAX3349EA Просмотр технического описания (PDF) - Maxim Integrated

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MAX3349EA

USB 2.0 Full-Speed Transceiver with UART Multiplexing Mode

Maxim Integrated 

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

USB Mode

In USB mode, the MAX3349EA 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 sus-

pend input SUS logic-high to force the MAX3349EA into

a low-power operating mode and disable the differen-

tial USB receiver (Table 3b).

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

GND with a 0.1µF ceramic capacitor as close to the

device as possible. There are high-impedance resistors

~2MΩ to ground on D+ and D- to prevent floating

nodes when in UART mode and nothing is connected.

Operating Modes

The MAX3349EA 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

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

logic-low otherwise. The MAX3349EA operates in USB

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

BD is logic-low.

UART Mode

The MAX3349EA 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 MAX3349EA 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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