Datasheet
MAX3421E
USB Peripheral/Host Controller
with SPI Interface
26
Maxim Integrated
inputs, and the GPX pin is configured to serve as a sec-
ond MAX3421E interrupt pin that activates only when a
GPIN pin changes state. One of the eight GPOUT pins
turns the V
BUS
switch on and off. Seven MAX3421E
GPIN and GPOUT pins are available to the system.
Short-Circuit Protection
The MAX3421E withstands V
BUS
shorts to D+ and D-
on the USB connector side of the 33Ω series resistors.
ESD Protection
D+, D-, and VBCOMP possess extra protection against
static electricity to protect the devices up to ±15kV. The
ESD structures withstand high ESD in all operating
modes: normal operation, suspend mode, and powered
down. VBCOMP and V
CC
require 1µF ceramic capacitors
connected to ground as close to the pins as possible. D+,
D-, and VBCOMP provide protection to the following limits:
• ±15kV using the Human Body Model
• ±8kV using the Contact Discharge method specified
in IEC 61000-4-2
• ±12kV using the IEC 61000-4-2 Air-Gap Method
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 22 shows the Human Body Model, and Figure 23
shows the current waveform generated when dis-
charged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of inter-
est, which then discharges into the test device through
a 1.5kΩ resistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. It does not specifi-
cally refer to integrated circuits. The major difference
between tests done using the Human Body Model and
IEC 61000-4-2 is a higher peak current in IEC 61000-4-
2, due to lower series resistance. Hence, the ESD with-
stand voltage measured to IEC 61000-4-2 generally is
lower than that measured using the Human Body
Model. Figure 24 shows the IEC 61000-4-2 model. The
MAX3421E
V
CC
V
L
INT
MOSI
MISO
SCLK
D+
D-
D+
D-
VBCOMP
SS
GND
V
BUS
33Ω
33Ω
5V SWITCH WITH
CURRENT LIMIT
AND OC DETECT
μP
USB
"A" CONNECTOR
GND
4.7μF
5V
XI
XO
C
XI
C
XO
12MHz
OUT IN
GPOUT
GPIN
ON
FLAG
3.3V
REGULATOR
WITH POR
1.0μF
CERAMIC
0.1μF
GPX
V
CC
GND
INT1
INT2
RES
Figure 21. MAX3421E in a Host Application