MAX14502AETL+ Maxim Integrated Products, MAX14502AETL+ Datasheet - Page 32

• 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 have four power-supply
inputs (Table 6). Bypass V
high-frequency, surface-mount ceramic capacitors as
close as possible to the supply pins.
Table 6. Power-Supply Inputs
Power-supply inputs:
1) V
2) V
3) V
4) V
32
SUPPLY
USB analog switches, PLL subsystem, and the USB
2.0 transceiver. This regulator can be internal to a
power-management IC, or it can be discrete and is
recommended to be powered from USB VBUS. This
supply must be present when the MAX14500–
MAX14503 are used in Card Reader mode to pass
USB signals in Pass Thru mode.
digital logic/internal microcontroller/flash memory.
There is an internal +1.8V LDO (CLDO) with shut-
down controlled by the state of the MODE input and
internal logic.
card level translator and SD card switches. V
needs to be present to pass SD signals in Pass Thru
mode.
digital I/O and I
V
V
V
V
TM
CC
SD
IO
______________________________________________________________________________________
TM
CC
SD
IO
Host Interface Power. This supply powers the
USB Transceiver Power. This supply powers the
SD Card Power. This supply powers the SD
Digital Logic Power. This supply powers the
USB transceiver and USB
switch power
Digital core 1.8V LDO
SD card level translator and SD
switches
Host microprocessor level
translator
2
C interface.
FUNCTION
CC
Power-Supply Modes
, V
IO
, V
SD
, and V
+2.91 to +3.4
+2.1 to +3.6
+2.0 to +3.6
+1.5 to +3.6
RANGE (V)
TM
with
SD
Power modes:
1) Idle. Only V
2) Pass Thru Mode. V
3) Card Reader Mode. All supplies are needed. When
The MAX14500–MAX14503 support Hi-Speed USB and
requires careful PCB layout. Use controlled-impedance
matched traces of equal lengths to the USB connector
with no discontinuities and a minimum number of
feedthroughs. All SD traces (CLK, CMD, DAT_) should
be of equal lengths and as short as possible.
I
to data and clock lines. There are tradeoffs between
power dissipation and speed, and a compromise must
be made in choosing pullup resistor values. Every
device connected to the bus introduces some capaci-
tance, even when the device is not in operation. I
specifies 300ns rise time to go from low to high (30% to
70%) for fast mode, which is defined for data rates up to
400kbps. To meet the rise time requirement, choose
pullup resistors so the rise time (t
where t
becomes too slow, the setup and hold times may not be
met and waveforms may not be recognized.
2
C requires pullup resistors to provide a logic-high level
can be updated, but no operation is possible.
voltage level at MODE can be detected. To allow
USB pass thru, the V
To allow SD pass thru, V
sent. Each supply is independent from the others
and no power-supply sequencing is required.
the card reader is actively transferring data, this mode
draws the most current, mainly from V
R
≈ 0.85 x R
IO
is required to be present. I
PULLUP
Choosing Pullup Resistors
IO
TM
needs to be present so the
Layout Considerations
supply needs to be present.
x C
SD
BUS
supply needs to be pre-
R
. If the transition time
) is less than 300ns
CC
and V
2
C registers
TM
.
2
C