Pcb layout, Driving high-capacitive load, Wire interface translation – Rainbow Electronics MAX13047E User Manual

Page 12: Push-pull vs. open-drain driving, Timing characteristics

MAX13046E/MAX13047E

1-Wire Interface Translation

The MAX13046E/MAX13047E are ideal for level transla-
tion between a low-voltage ASIC and 1-Wire device. A
typical application involves interfacing a low-voltage
microprocessor to an external memory, such as the
DS2502. The maximum data rate depends on the
1-Wire device. For the DS2502, the maximum data rate
is 16.3kbps. A 5kΩ pullup resistor is recommended
when interfacing with the DS2502.

Push-Pull vs. Open-Drain Driving

The MAX13046E/MAX13047E can be driven in a push-
pull or open-drain configurations. For open-drain con-
figuration, internal 10kΩ resistors pull up I/O V

and I/O

to their respective power supplies. See the

Timing

Characteristics

table for maximum data rates when

using open-drain drivers.

PCB Layout

The MAX13046E/MAX13047E require good PCB layout
for proper operation and optimal rise/fall time perfor-
mance. Ensure proper high-frequency PCB layout even
when operating at low data rates.

Driving High-Capacitive Load

Capacitive loading on the I/O lines impacts the rise time
(and fall time) of the MAX13046E/MAX13047E when dri-
ving the signal lines. The actual rise time is a function of
the load capacitance, parasitic capacitance, the supply
voltage, and the drive impedance of the MAX13046E/
MAX13047E.

Operating the MAX13046E/MAX13047E at a low data rate
does NOT increase capacitive load driving capability.

Single- and Dual-Bidirectional
Low-Level Translator

______________________________________________________________________________________

100%

90%

36.8%

TIME

CURRENT WAVEFORM

PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)

10%

AMPERES

Figure 2b. Human Body Current Waveform

CHARGE-CURRENT-

LIMIT RESISTOR

DISCHARGE

RESISTANCE

STORAGE
CAPACITOR

100pF

1500

HIGH-

VOLTAGE

SOURCE

DEVICE

UNDER

TEST

Figure 2a. Human Body ESD Test Model

100%

90%

60ns

10%

tr = 0.7ns TO 1ns

PEAK

30ns

Figure 3b. IEC 61000-4-2 ESD Generator Current Waveform