Rainbow Electronics DS8314 - Manual (Page 16)

DS8313/DS8314
Smart Card Interface
16 ______________________________________________________________________________________
Applications Information
Performance can be affected by the layout of the appli-
cation. For example, an additional cross-capacitance of
1pF between card reader contacts C2 (RST) and C3
(CLK) or C2 (RST) and C7 (I/O) can cause contact C2
to be polluted with high-frequency noise from C3 (or
C7). In this case, include a 100pF capacitor between
contacts C2 and CGND.
Application recommendations include the following:
• Ensure there is ample ground area around the
DS8313/DS8314 and the connector; place the
DS8313/DS8314 very near to the connector; decou-
ple the V
DD and V DDA lines separately. These lines
are best positioned under the connector.
• The device and the host microcontroller must use
the same V DD supply. Pins CLKDIV1, CLKDIV2,
RSTIN, PRES, I/OIN, 5V/3V, 1_8V, CMDVCC, and
OFF are referenced to V
DD
; if pin XTAL1 is to be
driven by an external clock, also reference this pin
to V
DD .
• Trace C3 (CLK) should be placed as far as possi-
ble from the other traces.
• The trace connecting CGND to C5 (GND) should
be straight (the two capacitors on C1 (V CC ) should
be connected to this ground trace).
• Avoid ground loops between CGND and GND.
• Decouple V
DDA
and V
DD
separately. If two sup-
plies are the same in the application, they should
be connected in a star on the main trace
With all these layout precautions, noise should be kept to
an acceptable level and jitter on C3 (CLK) should be less
than 100ps. Reference layouts are available on request.
Technical Support
For technical support, go to https://support.maxim-
ic.com/micro .
Selector Guide
Note: Contact the factory for availability of other variants and package options.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
* Future product—contact factory for availability.
PART
LOW STOP-MODE
POWER
LOW ACTIVE-
MODE POWER
PRES POLARITY V DDA INPUTS PIN-PACKAGE
DS8313-RJX+ Yes Yes Positive 2 28 TSSOP
DS8313-RRX+ Yes Yes Positive 2 28 SO
DS8313L-RJX+* Yes Yes Negative 2 28 TSSOP
DS8313L-RRX+* Yes Yes Negative 2 28 SO
DS8314-RJX+* Yes Yes Positive 1 28 TSSOP
DS8314-RRX+* Yes Yes Positive 1 28 SO
DS8314L-RJX+* Yes Yes Negative 1 28 TSSOP
DS8314L-RRX+* Yes Yes Negative 1 28 SO