AN1978 STMicroelectronics, AN1978 Datasheet - Page 9

• Manufacturer Part Number: AN1978
• Description: ST8004: SMART CARD INTERFACE
• Manufacturer: STMicroelectronics

Figure 11: OFF behaviour on VDD drop.
Figure 12: Deactivation sequence automatically when spikes on VDD are present.
Conditions:
V
V
V
5/3V=L.
CH1:CMDVCC
CH2: VDD
CH3: OFF
CH4: Vcc
When the V
the Vth2 value (about 2.1V) a
deactivation sequence starts and
the OFF pin goes low until
CMDVCC rising edge happens.
THSEL
DD
DDP
=4V to 2V;
Conditions:
Conditions:
V
V
V
V
V
V
5/3V=H.
5/3V=H.
CH1: Vcc
CH1: Vcc
CH2: V
CH2: V
CH3: RST pin.
CH3: RST pin.
When the V
When the V
down the Vth3 value (about
down the Vth3 value (about
3.0V) for more than 20µs. a
3.0V) for more than 20µs. a
deactivation
deactivation
starts; the RST pin (CH3) is
starts; the RST pin (CH3) is
the first that goes low.
the first that goes low.
=5V;
THSEL
THSEL
DD
DD
DDP
DDP
= Floating;
AN1978 - APPLICATION NOTE
=4.5V to 3V;
=4.5V to 3V;
=5V;
=5V;
= GND;
= GND;
DD
DD
DD
.
.
voltage falls below
DD
DD
voltage falls
voltage falls
sequence
sequence
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