MC145574AAC Freescale Semiconductor, MC145574AAC Datasheet - Page 121

• Manufacturer Part Number: MC145574AAC
• Description: IC TRANSCEIVER ISDN 32-LQFP
• Manufacturer: Freescale Semiconductor
• Type: Transceiverr

Specifications of MC145574AAC

• Voltage - Supply: 4.75 V ~ 5.25 V
• Mounting Type: Surface Mount
• Package / Case: 32-LQFP
• Number Of Line Interfaces: 1
• Control Interface: HDLC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of Drivers/receivers: -
• Protocol: -
• Lead Free Status / Rohs Status: Compliant

MOTOROLA
17.2.1
17.2.2
17.1
17.2
POWER SUPPLY STRATEGY
The MC145574 operates from a 5 V
This regulator has an output of 3.2 V. This regulated 3 V supply powers all of the internal digital logic,
resulting in reduced power consumption. The analog receiver/transmitter blocks are powered from
the 5 V supply.
The 3 V regulated output is present on the V DD 3 pin. A capacitor of 100 nF should be connected
between this pin and V SS to provide filtering for the internal regulator.
If a more efficient 3 V supply is available in the application circuit, then the V DD 3 pin can be driven
directly with this external supply. The internal 3 V regulator should then be disabled via the SCP to
gain a further improvement in device power consumption. This can be achieved by setting OR7(7).
The 5 V supply is still required when an external 3 V supply is being used.
The digital output drivers have a separate +ve supply pin, V DD I/O. This pin should be connected to
V DD 5 if 5 V output drivers are required, or the V DD 3 pin if 3 V output drivers are required. This option
allows the device to be easily interfaced to 3 V or 5 V CMOS or TTL devices. Using 3 V drivers will
give reduced power consumption while still being able to interface to 3 V CMOS and TTL devices.
All the digital inputs operate from the 3 V regulated supply (V DD 3) and are TTL and CMOS compatible.
The input ESD protection is connected to V DD 5 (the 5 V supply) ensuring that the inputs are compatible
with 3 V or 5 V CMOS and TTL input levels.
The 15.36 MHz crystal oscillator is powered from the 3 V regulated supply (V DD 3) to minimize its
power consumption. The XTAL oscillator circuit can be disabled via the SCP control bit (OR8(5)) if
an external 15.36 MHz clock source is available, further improving power consumption.
POWER MODES
The MC145574 has four distinct modes in which the maximum power consumption of the device is
specified.
Normal Operation
In this mode, the device is free to operate and activate or be activated from the S/T–interface.
In this mode, the device consumes the maximum power when it is forced to transmit the 96 kHz test
signal into the correctly terminated (50
96 kHz test signal.
Transmit Power-Down
In this mode, the device has its transmit circuitry powered down. This is achieved by setting the NR0(2)
in the SCP. The receiver is still fully active and able to respond to S/T–interface initiated activation.
The power consumption is measured with RxINFO = INFO 0. This mode can be entered or exited
in SCP or GCI mode.
Freescale Semiconductor, Inc.
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MC145574
5% supply. The MC145574 has an on–chip linear regulator.
POWER MODE OPERATION
) interface circuit. The receiver should also be receiving a
17
17–1