sp207et-tr Exar Corporation, sp207et-tr Datasheet - Page 9

• Manufacturer Part Number: sp207et-tr
• Description: Sp207 -5v, 5-driver/3-receiver Rs-232, Uses Small 0.1?f Capacitors
• Manufacturer: Exar Corporation

Date:05/26/2005
A typical application of this function would be
where a modem is interfaced to a computer in a
power–down mode. The ring indicator signal
from the modem could be passed through an
active receiver in the SP2XXB/SP213 that is
itself in the shutdown mode. The ring indicator
signal would propagate through the SP2XXB/
SP213 to the power management circuitry of the
Figure 6. Wake–Up Timing
R
DISABLE
R
DISABLE
R
SD
SD
SD
POWER UP WITH SD ACTIVE (Charge pump in shutdown mode)
POWER UP WITH SD DISABLED (Charge pump in active mode)
EXERCISING WAKE–UP FEATURE
ENABLE
ENABLE
OUT
OUT
OUT
V
t
t
WAIT
ENABLE
CC
+5V
+5V
+5V
0V
0V
0V
= +5V ±10%; T
t
t
t
= 2ms typical, 3ms maximum
0 (POWERUP)
0 (POWERUP)
0 (POWERUP)
= 1ms typical, 2ms maximum
DISABLE
t
t
ENABLE
WAIT
DATA VALID
t
t
WAIT
ENABLE
A
= 25°C
DATA VALID
+5V High-Speed RS232 Transceivers
9
ENABLE
t
computer to power up the microprocessor and
the SP2XXB/SP213 drivers. After the supply
voltage to the SP2XXB/SP213 reaches +5.0V,
the SHUTDOWN pin can be disabled, taking
the SP2XXB/SP213 out of the shutdown mode.
All receivers that are active during shutdown
maintain 500mV (typ.) of hysteresis.
ENABLE
DATA VALID
DATA VALID
t
DISABLE
ENABLE
© Copyright 2005 Sipex Corporation
DATA VALID