ncn6001 ON Semiconductor, ncn6001 Datasheet - Page 16

• Manufacturer Part Number: ncn6001
• Description: Compact Smart Card Interface Ic
• Manufacturer: ON Semiconductor

DATA I/O LEVEL SHIFTER
that might exist between the microcontroller and the smart
card. A pulsed accelerator built−in circuit provides the fast
the I/O signal being Open Drain or Totem Pole on either
sides.
card system, provisions have been made to avoid CRD_IO
current overload. Depending upon the selected mode of
operation (ASYNC. or Sync), the card I/O line is
respectively connected to either I/O pin 1, or to the MOSI
register byte bit 2. On the other hand, the logic level present
at the card I/O is feedback to the mC via the MISO register
bit 3. The logic level present at pin 6 controls the connection
of the internal pullup as depicted in Table 6.
NOTE:
Table 6. I/O Pullup Resistor True Table
EN_RPU
The level shifter accommodates the voltage difference
The transaction is valid when the Chip Select pin is Low,
Since the device can operate either in a single or a multiple
From MOSI
decoding
High
Low
MOSI/b2
MOSI/b3
SYNC
EN_RPU
18 kW typical value
Internal 18 kW pullup active
Open, 18 kW disconnected
V
I/O Pullup Resistor
CC
I/O
9
GND
6
1
Q5
U1
R1
18 k
CARD ENABLE
V
Figure 7. Basic I/O Internal Circuit
Parallel Mode
Single Device
CC
Operation
Device
Q1
SEQ 1
POR
http://onsemi.com
NCN6001
200 ns
16
positive going transient according to the ISO7816−3
specifications. The basic I/O level shifter is depicted in
Figure 7.
NOTE: Both sides of the interface run with open drain load
LEVEL SHIFT
Q3
LOGIC AND
(worst case condition).
Figure 8. Typical I/O Rise and Fall Time
Q4
CRD_VCC
VCC
200 ns
Q2
GND
R2
Q5
18 k
13
20
CRD_VCC
CRD_IO