MAX14500 Datasheet, PDF (20/41 Pages) Maxim Integrated Products – Hi-Speed USB-to-SD Card Readers with Bypass

Hi-Speed USB-to-SD Card
Readers with Bypass
SD
SLOT2
CCLK2
CCMD2
4 CDAT2_[3:0]
SD
SLOT1
CCRD_PRST
CCLK1
CCMD1
4 CDAT1_[3:0]
SD PORT 2 SWITCHES
HCLK2
HCMD2
HDAT2_[3:0]
SD
4 ^PORT2
SD PORT 1 SWITCHES
HCRD_PRST
HCLK1
HCMD1
HDAT1_[3:0]
SD
PORT1
4
D+
CD+
USB
CONNECTOR _D-
CD-
SD CARD INTERFACE
USB HS
CARD READER
USB
TRANSCEIVER
MAX14500–
MAX14503
USB SWITCHES
HOST PROCESSOR
HOST
I/O
HD+
USB
HD-
Figure 7. Default Startup (Pass Thru Mode)
Default Power-Up (Pass Thru Mode)
In the default Pass Thru mode, the MAX14500–
MAX14503 are transparent and the existing host func-
tions (access to SD cards and USB) are preserved
(Figure 7). The host µP reads and writes data to the SD
card from the SD port, and can communicate to a PC
through its existing full-speed USB port. All of the fea-
tures of the original chipset are intact. The MAX14500–
MAX14503 sleep when in Pass Thru mode (WAKEUP =
0), when the MODE input is low, or when the MODE bits
[2:1] in control register (0x00) are set to Card Reader
mode, not active. In Sleep mode, the internal microcon-
troller is turned off and current consumption is mini-
mized. The settings for SD port switches for card 1 and
card 2 are controlled by SD port switch bits [4:3] in the
control register.
Card Reader Mode
In Card Reader mode, the PC communicates with the
SD card through USB with an internal Hi-Speed SD
card reader, bypassing the host µP. Figure 8 shows
card reader mode with SD card 1 connected to the PC
with the internal card reader. The 40-pin TQFN can
connect to a single SD card in Card Reader mode. With
the 56-bump WLP operating under I²C control, either
SD card can be selected for Card Reader mode.
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