DS8113 Datasheet, PDF (16/17 Pages) Maxim Integrated Products – Smart Card Interface

Smart Card Interface
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
DS8113 and the connector; place the DS8113
very near to the connector; decouple the VDD and
VDDA lines separately. These lines are best posi-
tioned under the connector, connected in a star on
the main trace.
• The DS8113 and the host microcontroller must use
the same VDD supply. Pins CLKDIV1, CLKDIV2,
RSTIN, PRES, AUX1IN, I/OIN, AUX2IN, 5V/3V,
1_8V, CMDVCC, and OFF are referenced to VDD;
if pin XTAL1 is to be driven by an external clock,
also reference this pin to VDD.
• 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 (VCC)
should be connected to this ground trace).
• Avoid ground loops among CGND, PGND, and
GND.
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, designs, and an
evaluation kit are available on request.
Selector Guide
PART
LOW STOP- LOW ACTIVE- PIN-
MODE POWER MODE POWER PACKAGE
DS8113-RNG+
Yes
Yes
28 SO
Note: Contact the factory for availability of other variants and
package options.
+Denotes a lead-free package.
Package Information
(For the latest package outline information, go to
www.maxim-ic.com/packages.)
PACKAGE TYPE
28 SO (300 mils)
DOCUMENT NO.
21-0042
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