tda8025hn NXP Semiconductors, tda8025hn Datasheet - Page 8

• Manufacturer Part Number: tda8025hn
• Description: Ic Card Interface
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8025_1
Product data sheet
8.2.1 Block diagram
8.2.2 Description
8.2 Voltage supervisors
After powering up the device, pin OFFN remains LOW until pins CMDVCCN and PRES
are both HIGH or pin CMDVCCN is HIGH and pin PRESN is LOW. During power off, pin
OFFN is driven LOW when V
When pin CMDVCCN is HIGH, the internal oscillator frequency (f
frequency (inactive) mode to reduce power consumption.
The voltage supervisors provide both the Power-On Reset (POR) and supply drop-out
detection functions. They control the internal regulated supply voltage (V
the microcontroller interface supply voltage (V
the TDA8025.
By monitoring both V
voltages are high enough to ensure correct operation of the TDA8025 and flawless
communication between it and the microcontroller. This information is combined and sent
to the digital controller in order to reset the TDA8025.
An extension of the power-on reset pulse width of
TDA8025 in inactive mode after the supply voltage power on or off sequences (see
Figure
Fig 4.
Fig 5.
(internal signal)
V
DD(INTREGD)
5).
V
ALARMN
th
Voltage supervisor circuit
Voltage supervisors V
+ V
V
hys
th
DD(INTREGD)
V
DD(INTF)
Power on
Rev. 01 — 6 April 2009
R1
R2
V
DD(INTREGD)
DD(INTREGD)
PORADJ
DD(INTREGD)
t
w(POR)
and V
DD(INTF)
is below the falling threshold voltage (V
and V
DD(INTF)
V
REFERENCE
, the voltage supervisors ensure these
Supply dropout
DD(INTREGD)
DD(INTF)
VOLTAGE
8 ms (t
) to ensure problem-free operation of
t
w(POR)
w(POR)
001aai961
osc(int)
) is used to maintain the
) is switched to Low
TDA8025
© NXP B.V. 2009. All rights reserved.
IC card interface
DD(INTREGD)
Power off
001aai962
th
).
) and
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