ncn4557 ON Semiconductor, ncn4557 Datasheet - Page 9

• Manufacturer Part Number: ncn4557
• Description: 1.8 V/3.0 V Dual Sim/sam/smart Card Power Supply And Level Shifter
• Manufacturer: ON Semiconductor

and level shifter able to handle independently 2 smart card
interfaces. When one of these interfaces is operating the
other one is not active and conversely. Class B (3.0 V) and
C (1.8 V) cards can be used.
using the pins SEL0, SEL1 and ENABLE according to
Table 1.
Level Shifters
that might exist between the microcontroller and the smart
card. The RESET and CLOCK level shifters are
mono−directional and feature both the same architecture.
automatically adapt the voltage difference between the
Table 1. CARD AND CRD_V
The NCN4557 is a dual LDO−based DC/DC converter
The Card and the CRD_V
The level shifters accommodate the voltage difference
The bidirectional I/O line provides a way to
ENABLE
1
1
1
1
0
SEL1
ENABLE
X
C
0
0
1
1
in
V
= 0.1 mF
BAT
SEL0
CC
X
0
1
0
1
CC
power supply are selected
SELECTION
Figure 9. Simplified Block Diagram of the LDO
Card# / CRD_V
Q1
A & B Disabled
Card A / 1.8 V
Card A / 3.0 V
Card B / 1.8 V
Card B / 3.0 V
APPLICATION INFORMATION
I
lim
Voltage Regulator
http://onsemi.com
CC
NCN4557
+
−
V
9
ref
GND
+
Card Supply Converter
Drop−Out Voltage Regulators capable to supply a current
in excess of 50 mA under 1.8 V or 3.0 V. These voltages are
selected according to Table 1. Using the Boolean input
ENABLE pin the NCN4557 device can be disabled setting
the circuit in a shutdown mode for which the power
consumption features values typically in the range of a few
tens of nA. Figure 9 shows a simplified view of the
NCN4557 voltage regulator. The CRD_V
internally current limited and protected against short
circuits. The short−circuit current IV
typically in the range of 30 mA to 60 mA.
the LDO the CRD_V
1.0 mF bypass ceramic capacitor to the ground. At the
input, V
ceramic capacitor.
controller and the card in both directions. In addition with
the pull−up resistor, a dynamic pullup circuit (Figure 10,
Q1 and Q2) provides a fast charge of the stray capacitance,
yielding a rise time fully within the ISO7816, EMV and
GSM specifications.
The built−it NCN4557 DC/DC converters are Low
In order to guarantee a stable and satisfying operating of
R2
R1
BAT
will be bypassed to the ground with a 0.1 mF
CC
output will be connected to a
Cout = 1.0 mF
CRD_V
CC
CC
varies with V
CC
output is
BAT