MAX14502AETL+ Maxim Integrated Products, MAX14502AETL+ Datasheet - Page 18

• Manufacturer Part Number: MAX14502AETL+
• Description: IC CARD READER USB-SD 40-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Smart Card Interface ICr

Specifications of MAX14502AETL+

• Applications: USB
• Interface: I²C
• Voltage - Supply: 1.8 V ~ 3.3 V
• Package / Case: 40-TQFN Exposed Pad
• Mounting Type: Surface Mount
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Hi-Speed USB-to-SD Card
Readers with Bypass
The MAX14500–MAX14503 can be added to devices
that have an SD card slot and a USB full-speed port
(12Mbps) to provide a Hi-Speed USB path to an SD
card bypassing the host microprocessor (µP), allowing
for faster SD card transfers (Figures 1–4). Without the
MAX14500–MAX14503, a host µP with a full-speed USB
port moves data between an SD card and a host PC at
12Mbps when transferring data from an SD card
through USB. The host µP has additional overhead
because it has to accept data from the SD cards,
process the data by putting it in USB format, and then
transfer the data through the USB port. The MAX14500–
MAX14503 create an alternate path from the SD card to
USB, providing USB Hi-Speed capability. By bypassing
the host µP using the MAX14500–MAX14503, SD card
read and write operations are not limited by host µP
overhead and USB full-speed data rates.
The MAX14500–MAX14503 operate in Pass Thru and
Card Reader mode. In Pass Thru mode, the MAX14500–
MAX14503 are transparent to the host µP. All read and
write operations pass from the host µP SD port to the SD
card without modification. All of the features of the original
device are intact and there is no need to change firmware
in the host µP. In Card Reader mode, the SD card is con-
nected to the PC with the internal USB Hi-Speed card
reader, bypassing the host µP.
Figure 6. I
18
______________________________________________________________________________________
SDA
SCL
2
C Timing Diagram
t
HD,STA
CONDITION
START
Detailed Description
t
LOW_I2C
t
R_I2C
t
HIGH_I2C
t
SU,DAT
t
F_I2C
t
HD,DAT
t
SU,STA
START CONDITION
The MAX14500–MAX14503 can be controlled in two
ways. The simple control method uses a single output
from a µP or ASIC to select Pass Thru or Card Reader
mode. Only one SD card can be used as a Hi-Speed
USB card reader in simple control. I
more configuration options and provides status informa-
tion along with error conditions and additional interrupts.
Two SD cards can be connected and each set of SD
port switches can be controlled independently (two SD
port version under I
must not change after V
With I
internal registers for configuration, error checking, con-
trol, and status reporting. The control and configuration
registers have various functions including wakeup, SD
card selection, interrupt enable, and SD switch settings.
The status registers give the status of errors, SD card
detection, power supplies, and interrupts. Putting the
MAX14500–MAX14503 to sleep puts the device into
Pass Thru mode. The state of SD port switches for card 1
and card 2 can be changed while in Pass Thru. Some
I
Card Reader mode. For register settings that involve
Card Reader mode, (when in Sleep mode), program-
ming the I
actions do not execute until the internal logic wakes up
or Card Reader mode is entered. The register map indi-
cates when register bit changes take effect.
REPEATED
2
C commands are executed upon waking up or entering
t
R_I2C
2
C control, the I
t
HD,STA
Timing Diagrams (continued)
2
C registers changes the values, but the
2
2
C control). The state of I2C_SEL
C bus is used to read and write to
IO
t
SU,STO
is applied.
t
F_I2C
CONDITION
STOP
t
BUF
2
C control allows
CONDITION
START