MAX14978 Datasheet, PDF (13/15 Pages) Maxim Integrated Products – SuperSpeed USB Passive Switch (Low/Full/Hi/SuperSpeed)

SuperSpeed USB Passive Switch
(Low/Full/Hi/SuperSpeed)
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents test
setup, test methodology, and test results.
Human Body Model
Figure 6a shows the Human Body Model, and Figure 6b
shows the current waveform it generates when dis-
charged into a low-impedance state. This model consists
of a 100pF capacitor charged to the ESD voltage of inter-
est, which is then discharged into the test device through
a 1.5kI resistor.
IEC 61000-4-2
The main difference between tests done using the Human
Body Model and IEC 61000-4-2 is higher peak current
in IEC 61000-4-2. Because series resistance is lower in
the IEC 61000-4-2 ESD test model (Figure 7a) the ESD-
withstand voltage measured to this standard is generally
lower than that measured using the Human Body Model.
Figure 7b shows the current waveform for the Q8kV IEC
61000-4-2 Level 4 ESD Contact Discharge test.
The Air Gap Discharge test involves approaching the
device with a charged probe. The Contact Discharge
method connects the probe to the device before the
probe is energized.
Layout
High-speed switches require proper layout and design
procedures for optimum performance. Keep design-
controlled impedance PCB traces as short as pos-
sible or follow impedance layouts per the SuperSpeed
USB specification. Ensure that power-supply bypass
capacitors are placed as close as possible to the device.
Multiple bypass capacitors are recommended. Connect
all grounds and the exposed pad to large ground planes
where possible.
R_C
1MΩ
RD
1500Ω
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
HIGH-
VOLTAGE
DC
SOURCE
CS
100pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
RC
50MΩ TO 100MΩ
RD
330Ω
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
HIGH-
VOLTAGE
DC
SOURCE
CS
150pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 6a. Human Body ESD Test Model
I_P 100%
90%
AMPERES
36.8%
10%
0
0 _tRL
I_R
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
TIME
t_DL
CURRENT WAVEFORM
Figure 6b. Human Body Current Waveform
Figure 7a. IEC 61000-4-2 ESD Test Model
I
100%
90%
10%
tR = 0.7ns TO 1ns
30ns
t
60ns
Figure 7b. IEC 61000-4-2 ESD Generator Current Waveform
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