Smart Card Interface

16

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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

Note: Contact the factory for availability of other variants and

package options.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

PART

LOW STOP-

MODE POWER

LOW ACTIVE-

MODE POWER

PIN-

PACKAGE

DS8113-RNG+

Yes

Yes

28 SO

DS8113-JNG+

Yes

Yes

28 TSSOP

PACKAGE TYPE

PACKAGE CODE

DOCUMENT NO.

28 SO (300 mils)

W28+6

21-0042

28 TSSOP

U28+2

21-0066

Package Information

For the latest package outline information and land patterns,

“-” in the package code indicates RoHS status only. Package

drawings may show a different suffix character, but the drawing

pertains to the package regardless of RoHS status.