TDA8024T-T NXP Semiconductors, TDA8024T-T Datasheet - Page 9

• Manufacturer Part Number: TDA8024T-T
• Description: IC SMART CARD INTERFACE 28-SOIC
• Manufacturer: NXP Semiconductors

Specifications of TDA8024T-T

• Controller Type: Smart Card Interface
• Interface: Analog
• Voltage - Supply: 2.7 V ~ 6.5 V
• Current - Supply: 1.5mA
• Operating Temperature: -25°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 568-2448-2

Philips Semiconductors
8.2.2
If an external resistor bridge is connected to pin PORADJ
(R1 and R2 in Fig.1), then the following occurs:
Input PORADJ is biased internally with a pull-down current
source of 4 A which is removed when the voltage on
pin PORADJ exceeds 1 V. This ensures that after
detection of the external bridge by the IC during power-on,
the input current on pin PORADJ does not cause
inaccuracy of the bridge voltage.
The minimum threshold voltage should be higher than 2 V.
The maximum threshold voltage may be up to V
8.2.3
The voltage supervisor is used as Power-on reset and as
supply dropout detection during a card session.
Supply dropout detection is to ensure that a proper
deactivation sequence is followed before the voltage is too
low.
For the internal voltage supervisor to function, the system
microcontroller should operate down to 2.35 V to ensure a
proper deactivation sequence. If this is not possible,
external resistor values can be chosen to overcome the
problem.
8.2.3.1
For a microcontroller supplied by 3.3 V with a 5%
regulator and with resistors R1, R2 having a 1%
tolerance, the minimum supply voltage is 3.135 V.
V
the actual values of nominal resistors R1 and R2.
This can be shown as
0.99
0.99
2004 July 12
PORADJ
The internal threshold voltage V
external voltage and by the hysteresis, therefore:
where V
The reset pulse width t
16 ms.
IC card interface
V
V
th2(ext)(rise)
th2(ext)(fall)
R1 < S1 < 1.01
R2 < S2 < 1.01
W
FOR THE
A
= k
bridge
PPLICATION EXAMPLES
Microcontroller requiring a 3.3 V 20% supply
ITH AN EXTERNAL DIVIDER ON PIN
=
V
=
= 1.25 V typ. and V
DD
TDA8024AT)
1
1
, where
+
+
R1
------ -
R2
R1
------ -
R2
R1 and
R2
W
k
is doubled to approximately
V
=
V
bridge
bridge
-------------------- -
S1
th2
S1
+
hys(ext)
–
+
S2
is overridden by the
V
------------------- -
V
------------------- -
hys(ext)
hys(ext)
2
with S1 and S2
2
= 60 mV typ.
PORADJ (
DD
.
NOT
9
Transposed, this becomes
If V1 = V
activation will always be possible if V
and deactivation will always be done for V
Activation is always possible for
and deactivation is always possible for
That is V1 = 1.31 V and V2 = 1.19 V
and
Suppose R1 + R2 = 100 k , then
Deactivation will be effective at
V2
If the microcontroller continues to function down to 2.80 V,
the slew rate on V
that clock CLK is correctly delivered to the card until
time t
8.2.3.2
For a microcontroller supplied by a 3.3 V with a 1%
regulator and with resistors R1, R2 having a 0.1%
tolerance, the minimum supply voltage is 3.267 V.
The same calculations as in Section 8.2.3.1 conclude:
Therefore
Deactivation will be effective at
V2
If the microcontroller continues to function down to 2.97 V,
the slew rate on V
ensure that clock CLK is correctly delivered to the card
until time t
1
1
-- -
R2
R1
------ -
R2
k
+
1
=
R1
------ -
R2
0.98
(1 + 1.02
(1 + 1.002
12
+
100 k
------------------ -
3.267
-------------- - 1
1.310
2.365
(see Fig.9).
1.01
---------- -
0.99
th(ext)(rise)(max)
12
R2
Microcontroller requiring a 3.3 V 10% supply
3.135
-------------- - 1
R1
------ -
R2
1.31
(see Fig.9).
–
=
= 42.3 k and R1 = 57.7 k .
R1
------ -
R2
1.365) = 2.847 V in any case.
=
100 k
------------------ -
–
DD
1.491) = 2.967 V in any case.
DD
2.49
1
0.998
should be less than 2 V/ms to ensure
=
+
should be less than 0.20 V/ms to
and V2 = V
1
0.98
0.99
---------- -
1.01
+
=
= 40.14 k and R1 = 59.86 k .
1.02
1.491
=
1.365
------- -
R2
R1
V
th(ext)(fall)(min)
DD
R1
------ -
R2
Product specification
PORADJ
1
-- -
k
V1
------ -
V
k
TDA8024
DD
PORADJ
> V1
V2
------ -
k
.
< V2.