MAX14500 Datasheet, PDF (31/41 Pages) Maxim Integrated Products – Hi-Speed USB-to-SD Card Readers with Bypass

Hi-Speed USB-to-SD Card
Readers with Bypass
MECHANICAL CARD
DETECT SWITCH
SD CARD
CCRD_PRST
CCMD1
CCLK1
CDAT1_[3:0]
MAX14500–MAX14503 SD
PORT1 SWITCH
≤ V_SD
HCRD_PRST
HCMD1
HCLK1
HDAT1_[3:0]
CARD PRESENT INPUT
HOST SD PORT
MECHANICAL CARD
DETECT SWITCH
MAX14500–MAX14503 SD
PORT2 SWITCH
≤ V_SD
SD CARD
CCMD2
CCLK2
CDAT2_[3:0]
HCMD2
HCLK2
HDAT2_[3:0]
CARD PRESENT INPUT
HOST SD PORT
Figure 21. Host Card Detection Schemes
SD Port Switches
The SD port analog switches change states immediately
whether the MAX14500–MAX14503 are in Sleep mode
(WAKEUP = 0) or awake. If the internal USB Hi-Speed
SD card reader is in operation, the SD card switches for
the selected path are opened automatically. Any writes
to the SD port switch bits for that path are ignored. The
SD port analog switches for the path not being used for
the card reader are controllable by the host µP, and any
writes to these bits affect state changes immediately.
Card Detection
The MAX14500–MAX14503 provide an analog switch to
pass the card present signal on SD card slot 1. This
allows the host µP to continue using the SD slot card
present switch (see Figure 21). The internal analog
switch can be bypassed if an alternate algorithm is
used to detect card data change. The second SD card
path does not provide this analog switch so if this path
is used for another SD card socket, an alternate card-
detection mechanism for the host µP may be needed. If
the second SD card path is used for an SD interface
NAND chip, no card detection is required.
The MAX14500–MAX14503 do not use the SD card slot
switch to detect insertion and removals. Instead, a pro-
tocol-based detection mechanism is used that polls for
the presence or absence of an SD card. This allows
both path 1 and path 2 to support an SD card slot with
removable SD cards without a connection between
the MAX14500–MAX14503 and the SD socket card pre-
sent switch. The pullup voltage for the card slot detec-
tion may be any voltage equal to or less than V_SD.
Enumeration
The MAX14500–MAX14503 enumerate to the USB
mass storage class and appear as a USB mass stor-
age device on most operating systems.
USB Hi-Speed vs. Full-Speed
The MAX14500–MAX14503 support USB Hi-Speed and
full-speed operation. The MAX14500–MAX14503 operate
at 480Mbps when plugged into a Hi-Speed USB host,
and at 12Mbps when plugged into a full-speed host.
USB VID/PID
Using I²C, the MAX14500–MAX14503 have dedicated
I²C registers for vendor identification (VID) and product
identification (PID). The programmed 16-bit default val-
ues are shown in the Register Map section. The factory
default values can be replaced with your company’s VID
and PID.
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