MAX14502AETL+ Maxim Integrated Products, MAX14502AETL+ Datasheet - Page 22

• 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
Figure 9. Card Reader Flow Chart
go to sleep. Because the BUSY output (BSY bit in I
indicates Card Reader mode, the host µP may monitor
this output after commanding a mode change to deter-
mine when the change takes place (Figure 9). If the host
requests the other SD card to enter Card Reader mode,
the busy flag deasserts and reasserts to let the host
know that the change took place.
The MAX14500–MAX14503 feature a very simple con-
trol scheme for entering Card Reader mode that
requires a single logic (GPIO) from the host µP. The
simple control may only be used with the single SD port
versions. When I2C_SEL is connected low at startup,
the MODE input controls whether the device is in Pass
Thru or Card Reader mode. Driving MODE low enables
Pass Thru mode (Figure 10), and the host µP has a
direct connection to the SD card and USB connector
through internal analog switches. Driving MODE high
enables Card Reader mode between SD card 1 and
the PC through the USB connector (Figure 11).
BERR/INT functions as the bridge error output BERR
that asserts for card reader errors. Interrupts are not
enabled, the clock source is set to the default as
22
______________________________________________________________________________________
Simple Control (I2C_SEL = Low)
IF ASLEEP
• DISCONNECT SD
• ENUMERATE SD CARD
• OPEN USB SWITCHES
SWITCHES FOR CARD READER
• ASSERT BUSY
• SET BUSY FLAG
• ENUMERATE PC
TO ENTER CARD
PASS THRU
REQUEST
IF AWAKE
READER
2
C)
defined by the part number, and the BERR and BUSY
outputs are active. Upon MODE transitioning high, SD
card 1 connects to the USB connector in Card Reader
mode and BUSY asserts low. The BUSY output indi-
cates that the device is in Card Reader mode. BUSY
may be important to the host µP, as the time to com-
plete enumeration/de-enumeration may take a long
time (> 100ms).
The MAX14500–MAX14503 feature I
allows access to internal registers for complete control
over configuration, SD port analog switches, interrupts,
clock configuration, advanced power-on states, and
error status. I
MAX14500–MAX14503 to be in Card Reader or Pass
Thru mode, and allows either SD card to be connected
in Card Reader mode. While a SD card is connected in
Card Reader mode, the other SD port analog switches
can be independently controlled serially through I
Using the I
the supply current while maintaining control over the
SD port switches.
• DEENUMERATE SD CARD
• RESTORE SD SWITCHES TO I
NO SD COMMAND IN PROGRESS
• DEENUMERATE PC
• CLOSE USB SWITCHES
• DEASSERT BUSY
• CLEAR BUSY FLAG
(TRANSFER DATA)
CARD READER
TO SLEEP OR
PASS THRU
REQUEST
2
C bus to put the device to sleep minimizes
2
C control uses I
2
I
C SETTINGS
2
C Control (I2C_SEL = High)
SD COMMAND
IN PROGRESS
2
C to serially program the
2
C control that
2
C.