Maxim Integrated
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www.maximintegrated.com
Evaluates: USB2GPIO
USB2GPIO# Adapter Board
Detailed Description of Hardware
The USB2GPIO# board uses the FT2232HQ (U1), a USB
2.0 high-speed (480Mbps)-to-UART/FIFO IC, to process
commands sent by a program running on the PC. Each
particular EV kit has its own custom software specific
to that kit. The operation of this board is USB-to-dual-
channel I
2
C and SPI engine with additional GPIO channels.
The subsystem block diagram and simplified power tree
are shown in
Figure 3
.
The VCCIO and +3.3V voltage supplies are generated
by two MAX1556ETBs (U5 and U6), 1.2A, highly efficient
PWM step-down DC-DC converters. The 5V supply volt-
age input for these ICs is provided by the Micro-USB
supply terminal available from the laptop. The 3V3 sup-
ply provides power to the FDTI chip’s VREGIN pin and
its internal oscillator through an LC filter, and the 4K
MICROWIRE EEPROM (93LC66BT). The USB-to-I
2
C/SPI
engine is powered by 3.3V at the VREGIN pin and the core
voltage of 1.8V for the IC is generated at VREGOUT. This
VCORE is used within the FTDI IC itself for its internal logic
processes and there is an external 12MHz crystal across
OSCI and OSCO pins of the FTDI IC. See
USB2GPIO#
Adapter Board Schematic
for details.
Pmod and Connector Supply Voltages
The USB2GPIO# is designed to supply power (V_OUT) to
external boards through the connectors X2 and X3. This
voltage is defined by the type of board connected to X3,
and when the user selects that tab in the Munich GUI,
V_OUT is automatically set to the correct level, either
1.8V, 2.5V, 3.3V, or 5.0V.
Figure 3. USB2GPIO# Subsystem Block Diagram
USB
FT2232HQ
U1
SWITCHES
MAX4983, U2, U4
DC-DC
MAX1556, U5
DC-DC
MAX1556, U6
12-PIN
X3
20-PIN
X2
+5V
VCCIO
+3V3
V_OUT
SPI/I2C
V_OUT
GPIO
SELE CT
VOLTAGE
OUTPUT
M1 - M5
V_OUT
VCCIO
+5V
M3
M1
VCCIO
+3V3
