NCN8025A ONSEMI [ON Semiconductor], NCN8025A Datasheet - Page 9

• Manufacturer Part Number: NCN8025A
• Description: Compact SMART CARD Interface IC
• Manufacturer: ONSEMI [ON Semiconductor]

9. Guaranteed by design and characterization.
POWER SUPPLY
power supplies: V
The applied V
goes below 2.30 V typical (UVLO
sequence is automatically performed. In that case the
interrupt (INT) pin is set Low.
to provide the 1.8 V, 3 V or 5 V power supply voltage
(CVCC) to the card. V
CVCC is the LDO output. The typical distributed reservoir
output capacitor connected to CVCC is 100 nF + 220 nF. The
capacitor of 100 nF is connected as close as possible to the
CVCC’s pin and the 220 nF one as close as possible to the
card connector C1 pin. Both feature very low ESR values
(lower than 50 mW). The decoupling capacitors on V
V
be connected close to the respective IC pins.
5 V continuously over the V
specification table), the absolute maximum current being
internally limited below 150 mA (Typical at 120 mA).
the pins VSEL0 and VSEL1 and according to the below table:
mode which can be 5V/3V (VSEL0 connected to Ground)
or 1.8V/3V (VSEL0 connected to V
VSEL1 are usually programmed before activating the smart
card interface that is when /CMDVCC is High.
They can be applied to the interface in any sequence. After
powering the device INT pin remains Low until a card is
inserted.
SMART CARD INTERFACE SECTION
F
T
Table 1. CVCC PROGRAMMING
DDP
CLKIN
Symbol
Temp
The NCN8025 / NCN8025A smart card interface has two
V
A Low Drop−Out (LDO) and low noise regulator is used
The CVCC pin can source up to 70 mA at 1.8 V, 3 V and
The card V
VSEL0 can be used to select the CVCC programming
There’s no specific sequence for applying V
debounce
I
I
T
I
CCLK
CRST
CI/O
T
deact
DD
VSEL0
act
respectively 100 nF and 10 mF + 100 nF have also to
0
0
1
1
SD
= 10 MHz)
is common to the system controller and the interface.
Debounce time PRES and PRES (Note 9)
CI/O, CAUX1, CAUX2 current limitation
CCLK current limitation
CRST current limitation
Activation Time (Note 9)
Deactivation Time (Note 9)
Shutdown temperature (Note 9)
CC
DD
voltage (CVCC) can be programmed with
range can go from 2.7 V up to 5.5 V. If V
VSEL1
DD
0
1
0
1
and V
DDP
DDP
DDP
is the LDO’s input voltage.
.
range (see corresponding
VDD
CVCC
DD
CI/O, CAUX1, CAUX2, CCLK, CRST, PRES, PRES (V
3.0 V
5.0 V
3.0 V
1.8 V
) a power−down
Rating
). VSEL0 and
DD
or V
DD
http://onsemi.com
DDP
and
DD
.
9
SUPPLY VOLTAGE MONITORING
Power−On Reset (POR) circuitry and the under−voltage
lockout (UVLO) detection (V
detection). PORADJ pin allows the user, according to the
considered application, to adjust the V
If not used PORADJ pin is connected to Ground
(recommended even if it may be left unconnected).
prevent under voltage operation. At power up, the system
initializes the internal logic during POR timing and no further
signal can be provided or supported during this period.
reached the minimum V
/ NCN8025A will detect an Under−Voltage situation when
the input supply voltage will drop below 2.30 V typical.
When V
deactivation sequence is performed.
the V
according to the below relationship considering an external
resistor divider R1 / R2 (see block diagram Figure 1):
threshold (V
can be interesting to adjust this threshold at a higher value
and by the way increase the V
level which enables a deactivation sequence if the V
voltage is too low.
minimum supply voltage insuring a correct operating is
higher than 2.6 V; increasing UVLO
consequently necessary. Considering for instance a resistor
bridge with R1 = 56 kW, R2 = 42 kW and V
typical the V
to:
The supply voltage monitoring block includes the
The input supply voltage is continuously monitored to
The system is ready to operate when the input voltage has
The device is inactive during power−on and power−off of
PORADJ pin is used to modify the UVLO threshold
If PORADJ is connected to Ground the V
For example, there are microcontrollers for which the
DD
DD
supply (8 ms reset pulse).
UVLO +
goes down below the UVLO falling threshold a
DD
DD
falling) is typically 2.30 V. In some cases it
dropout detection level can be increased up
UVLO +
56k ) 42k
Min
30
30
5
−
−
−
−
DD
DD
42k
. Considering this, the NCN8025
= 3.3 V; V
R1 ) R2
R2
DD
V
150
Typ
8
−
−
−
−
−
POR−
supply dropout detection
DDP
DD
V
VDD
POR
DD
+ 2.96 V
= 5 V; T
voltage dropout
Max
UVLO threshold.
100
250
12
15
70
20
(V
−
POR−
DD
amb
DD
falling) is
= 1.27 V
= 25°C;
UVLO
Unit
(eq. 1)
(eq. 2)
mA
mA
mA
ms
°C
ms
ms
DD