DS8024-RJX+ Maxim Integrated Products, DS8024-RJX+ Datasheet - Page 11

• Manufacturer Part Number: DS8024-RJX+
• Description: IC INTERFACE SMART CARD 28-TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of DS8024-RJX+

• Applications: Smart Card
• Interface: Analog
• Voltage - Supply: 2.7 V ~ 6 V
• Package / Case: 28-TSSOP
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

When the host microcontroller is done communicating
with the smart card, it sets the CMDVCC line high to
execute an automatic deactivation sequence and
returns the card interface to the inactive mode.
The following sequence of events occurs during a
deactivation sequence (Figure 5):
The card voltage (V
80mA continuously at 5V or 65mA at 3V. An internal
overload detector triggers at approximately 120mA.
Current samples to the detector are filtered. This allows
spurious current pulses (with a duration of a few µs) up
to 200mA to be drawn without causing deactivation.
The average current must stay below the specified
maximum current value.
See the Applications Information section for recommen-
dations to help maintain V
The DS8024 integrates circuitry to monitor the following
fault conditions:
1) RST goes low (t
2) CLK is held low (t
3) I/O, AUX1, and AUX2 are pulled low (t
4) V
5) When V
6) All card contacts become low impedance to GND;
7) The internal oscillator returns to its lower frequency.
• Short-circuit or high current on V
• Card removal while the interface is activated
• V
• Card voltage generator operating out of the speci-
• Overheating
times the period of the internal oscillator (approxi-
mately 25µs).
tion sequence is complete (at t
I/OIN, AUX1IN, and AUX2IN remain at V
up through an 11kΩ resistor).
fied values (V
too high)
CC
DD
starts to fall (t
dropping below threshold
CC
reaches its inactive state, the deactiva-
______________________________________________________________________________________
Deactivation Sequence
DDA
10
CC
12
).
14
too low or current consumption
) generator can supply up to
= t
CC
= t
10
10
voltage accuracy.
Fault Detection
+ 0.5 × T), where T is 64
V
+ 1.5 × T).
CC
DE
CC
).
Generator
13
= t
DD
10
(pulled
+ T).
There are two different cases for how the DS8024
reacts to fault detection (Figure 6):
The DS8024 has a debounce feature with an 8ms typi-
cal duration (Figure 6). When a card is inserted, output
OFF goes high after the debounce time delay. When
the card is extracted, an automatic deactivation
sequence of the card is performed on the first true/false
transition on PRES and output OFF goes low.
The DS8024 (like the TDA8024) does not support a low-
power stop mode. For applications requiring low-power
support, refer to the DS8113.
The DS8024 supports two smart card V
and 5V. The power select is controlled by the 5V/3V
signal as shown in Table 3. V
ed to a logic-high state, and V
to a logic-low state.
Table 3. V
• Outside a Card Session (CMDVCC High). Output
• Within a Card Session (CMDVCC Low). Output
5V/3V
Smart Card Interface
OFF is low if a card is not in the card reader and
high if a card is in the reader. The V
monitored—a decrease in input voltage generates
an internal power-on reset pulse but does not
affect the OFF signal. Short-circuit and tempera-
ture detection are disabled because the card is
not powered up.
OFF goes low when a fault condition is detected,
and an emergency deactivation is performed auto-
matically (Figure 7). When the system controller
resets CMDVCC to high, it may sense the OFF
level again after completing the deactivation
sequence. This distinguishes between a card
extraction and a hardware problem (OFF goes high
again if a card is present). Depending on the con-
nector’s card-present switch (normally closed or
normally open) and the mechanical characteristics
of the switch, bouncing can occur on the PRES sig-
nals at card insertion or withdrawal.
0
0
1
1
Stop Mode (Low-Power Mode)
CC
CMDVCC
Smart Card Power Select
0
1
0
1
Select and Operation Mode
SELECT (V)
V
CC
3
3
5
5
CC
CC
is 5V if 5V/3V is assert-
is 3V if 5V/3V is pulled
CARD INTERFACE
CC
Inactivated
Inactivated
Activated
Activated
STATUS
DD
voltages: 3V
supply is
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