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NCN4557
http://onsemi.com
4
PIN DESCRIPTIONS
PIN
Name
Type
Description
1
CRD_VCCB
POWER
This pin is connected to the Card power supply pin (C1) (Card B).The corresponding LDO is
programmable using the pins SEL0, SEL1 and ENABLE to provide 1.8 V, 3.0 V or 0 V (disable).
CRD_VCCB can not be active when CRD_VCCA is active and conversely.
2
VDD
POWER
This pin is connected to the controller power supply. It configures the level shifter input stage to accept
the signal coming from the microcontroller. A 0.1
mF capacitor shall be used to bypass the power supply
voltage. When VDD is below 1.5 V typical CRD_VCCA and B are disabled; the NCN4557 comes into a
shutdown mode.
3
VBAT
POWER
DC/DC converter power supply input shared by the LDOs A & B. This pin has to be bypassed by a
0.1
mF capacitor.
4
CRD_VCCA
POWER
This pin is connected to the Card power supply pin (C1) (Card A).The corresponding LDO is
programmable using the pins SEL0, SEL1 and ENABLE to provide 1.8 V, 3.0 V or 0 V (disable).
CRD_VCCA can not be active when CRD_VCCB is active and conversely.
5
CRD_CLKA
OUTPUT
This pin is connected to the clock pin (C3) of the card connector A. The clock (CLK) signal comes from
the external clock generator (standalone clock source or microcontroller). The internal level shifter
adapts the voltage levels CLK to CRD_CLKA. An internal active pull down NMOS device maintains this
pin to Ground during either the CRD_VCCA startup sequence, or when CRD_VCCA = 0 V.
6
CRD_RSTA
OUTPUT
This pin is connected to the RESET pin (C2) of the card connector A. A level translator adapts the
RESET signal from the microcontroller to the external card A. The output current is internally limited to
15 mA max. Similarly to the CRD_CLK A or B pins this pin is maintained Low when CRD_VCCA = 0 V
and during the corresponding LDO transient phase of powerup.
7
CRD_I/OA
INPUT /
OUTPUT
This pin handles the connection to the serial I/O pin (C7) of the card connector A. A bidirectional level
translator adapts the serial I/O signal between the card and the microcontroller. A 14 k
W (typical)
pullup resistor provides a High Impedance state to the card I/O link; during the operating phase, a
dynamic pullup circuit is activated making the CRD_I/OA rise time compliant with the ISO7816, EMV,
GSM and related standards. An internal active pulldown MOS device forces this pin to Ground during
either the CRD_VCCA startup sequence or when CRD_VCCA = 0 V. The CRD_I/OA pin is internally
limited by a 15 mA max current.
8
I/O
INPUT /
OUTPUT
This pin is connected to an external microcontroller or cellular phone management unit (Baseband circuit
or PMU). A bidirectional level translator adapts the serial I/O signal between the smart card A or B and
the controller. Only one card, the selected card, communicates through the bidirectional I/O interface. A
builtin 18 k
W typical resistor provides a high impedance state when the interface is not activated. An
additional dynamic pullup circuit accelerates the I/O rise time making the bidirectional channel perfectly
balanced in regards to the standard rise time requirements.
9
RST
INPUT
The RESET signal present at this pin is connected to the card through the internal level shifter which
translates the levels according to the CRD_VCCA or B programmed value.
10
CLK
INPUT
The clock signal, coming from the external controller, must have a Duty Cycle within the Min/Max values
defined by the specification (typically 50%). The builtin level shifter translates the input signal to the
external card CLK input.
11
SEL1
INPUT
SEL1 allows the selection of the Card A or B (Table 1).
SEL1 = Low
! Card A selected
SEL1 = High
! Card B selected
12
SEL0
INPUT
SEL0 allows programming CRD_VCCA or B (1.8 V or 3.0 V) (Table 1).
SEL0 = Low
! CRD_VCCA/B = 1.8 V
SEL0 = High
! CRD_VCCA/B = 3.0 V
13
ENABLE
INPUT
Power Up and Down pin:
ENABLE = Low
! Low current shutdown mode activated
ENABLE = High
! Normal Operation
A Low level on this pin switches off the card interface.
14
CRD_I/OB
INPUT /
OUTPUT
This pin handles the connection to the serial I/O pin (C7) of the card connector B. A bidirectional level
translator adapts the serial I/O signal between the card and the microcontroller. A 14 k
W (typical)
pullup resistor provides a High Impedance state to the card I/O link; during the operating phase a
dynamic pullup circuit is activated making the CRD_I/OB rise time compliant with the ISO7816, EMV,
GSM and related standards. An internal active pulldown MOS device forces this pin to Ground during
either the CRD_VCCB startup sequence or when CRD_VCCB = 0 V. The CRD_I/OB pin is internally
limited by a 15 mA maximum current.
15
CRD_RSTB
OUTPUT
This pin is connected to the RESET pin of the card connector B. A level translator adapts the RESET
signal from the microcontroller to the external card B. The output current is internally limited by a 15 mA
max current. Similarly to the CRD_CLK A or B pins this pin is maintained Low when CRD_VCCB = 0 V
and during the corresponding LDO transient phase of powerup.
16
CRD_CLKB
OUTPUT
This pin is connected to the clock pin (C3) of the card connector B. The clock (CLK) signal comes from
the external clock generator (standalone clock source or microcontroller). The internal level shifter
adapts the voltage levels CLK to CRD_CLKB. An internal active pull down NMOS device maintains this
pin to Ground during either the CRD_VCCB startup sequence, or when CRD_VCCB = 0 V.
17
GND
This pin number is the Exposed Pad which is the electrical Ground of the device. It must be soldered to
the PCB ground plane.