MAX3421EEHJ+T Maxim Integrated Products, MAX3421EEHJ+T Datasheet - Page 3

• Manufacturer Part Number: MAX3421EEHJ+T
• Description: IC USB PERIPH/HOST CNTRL 32TQFP
• Manufacturer: Maxim Integrated Products

Specifications of MAX3421EEHJ+T

• Controller Type: USB Peripheral Controller
• Interface: USB/Serial
• Voltage - Supply: 3 V ~ 3.6 V
• Current - Supply: 15mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-TQFP, 32-VQFP
• For Use With: MAX3421EVKIT-1+ - EVAL KIT FOR MAX3421E
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 2. The MAX3421E Connected to a Large Chip
Figure 3. Optical Isolation of USB Using the MAX3421E
Figure 4. The MAX3421E in an Embedded Host Application
V
POWER
ON/OFF
BUS
5V
USB
USB
MICRO,
ASIC,
DSP
REGULATOR
REGULATOR
FAULT
3.3V
3.3V
SPI
3, 4
INT
REGULATOR
MAX3421E
MAX3421E
SWITCH
V
3.3V
_______________________________________________________________________________________
BUS
MAX3421E
3, 4
SPI
INT
O
O
S
L
A
T
R
S
I
USB
"A"
SCLK
MOSI
MISO
SS
INT
V
GND
BUS
D+
D-
ASIC,
DSP,
USB Peripheral/Host Controller
ETC.
MICRO
USB
ASIC
"B"
DSP
POWER RAIL
PERIPHERAL
LOCAL
GND
LOCAL
POWER
USB
Typical Application Circuits (continued)
Two MAX3421E features make it easy to connect to
large, fast chips such as ASICs and DSPs (Figure 2).
First, the SPI interface can be clocked up to 26MHz.
Second, the V
running the system interface at a lower voltage than
the 3.3V required for V
The MAX3421E provides an ideal method for electrically
isolating a USB interface (Figure 3). USB employs flow
control in which the MAX3421E automatically answers
host requests with a NAK handshake, until the micro-
processor completes its data-transfer operations over
the SPI port. This means that the SPI interface can run
at any frequency up to 26MHz. Therefore, the designer
is free to choose the interface operating frequency and
to make opto-isolator choices optimized for cost or per-
formance.
Figure 4 shows a block diagram for a system in which
the MAX3421E operates as a USB host. A USB host
supplies 5V power to the V
nector to power USB peripherals. A system that pro-
vides power to an external peripheral should use
protection circuitry on the power pin to prevent an
external overcurrent situation from damaging the sys-
tem. A V
power control plus two additional features: it limits the
current delivered to the peripheral (for example to
200mA), and it indicates a fault (overcurrent) condition
to the SPI controller. Maxim offers a variety of V
switches with various current limits and features.
Consult the Maxim website for details.
A 3.3V regulator (for example, the MAX6349TL) powers
the MAX3421E, and optionally the system controller. If
the system controller operates with a lower voltage, the
MAX3421E SPI and I/O interface can run at the lower
voltage by connecting the system voltage (for exam-
ple, 2.5V or 1.8V) to the MAX3421E V
BUS
with SPI Interface
switch, such as the MAX4789, provides
L
pin and internal level translators allow
CC
.
BUS
pin of the USB “A” con-
L
pin.
BUS
3