MAX3224 Просмотр технического описания (PDF) - Maxim Integrated
Номер в каталоге
Компоненты Описание
Список матч
MAX3224
Maxim Integrated
MAX3224 Datasheet PDF : 20 Pages
| |||
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
Table 1. Output Control Truth Table
OPERATION
STATUS
FORCEON FORCEOFF
VALID
RECEIVER
LEVEL
Shutdown
(Forced Off)
X
0
X
Normal
Operation
1
1
X
(Forced On)
Normal
Operation
(AutoShutdown
0
1
X
Plus)
Shutdown (Auto-
Shutdown Plus)
0
1
X
Normal
Operation
INVALID*
1
Yes
Normal
Operation
INVALID*
1
X
Shutdown
INVALID*
1
No
Normal
Operation
INVALID* INVALID**
Yes
(AutoShutdown)
Shutdown
(AutoShutdown)
INVALID*
INVALID**
No
X = Don’t care
*INVALID connected to FORCEON
**INVALID connected to FORCEON and FORCEOFF
RECEIVER OR
TRANSMITTER
EDGE WITHIN
30sec
T_OUT
X
High-Z
X
Active
Yes
Active
No
High-Z
X
Active
Yes
Active
No
High-Z
X
Active
X
High-Z
R_OUT
(MAX3224/
MAX3225/
MAX3226/
MAX3227)
Active
Active
Active
Active
Active
Active
Active
Active
Active
R_OUT
(MAX3244/
MAX3245)
High-Z
Active
Active
Active
Active
Active
Active
Active
High-Z
R2OUTB
(MAX3244/
MAX3245)
Active
Active
Active
Active
Active
Active
Active
Active
Active
RS-232 Receivers
The receivers convert RS-232 signals to CMOS-logic
output levels. The MAX3224–MAX3227 feature inverting
outputs that always remain active (Table 1). The
MAX3244/MAX3245 have inverting three-state outputs
that are high impedance when shut down (FORCEOFF
= GND) (Table 1).
The MAX3244/MAX3245 feature an extra, always
active, noninverting output, R2OUTB. R2OUTB output
monitors receiver activity while the other receivers are
high impedance, allowing Ring Indicator applications to
be monitored without forward biasing other devices
connected to the receiver outputs. This is ideal for sys-
tems where VCC is set to ground in shutdown to
accommodate peripherals such as UARTs (Figure 2).
The MAX3224–MAX3227/MAX3244/MAX3245 feature
an INVALID output that is enabled low when no valid
RS-232 voltage levels have been detected on all receiv-
er inputs. Because INVALID indicates the receiver
input’s condition, it is independent of FORCEON and
FORCEOFF states (Figures 3 and 4).
AutoShutdown Plus Mode
The MAX3224–MAX3227/MAX3244/MAX3245 achieve a
1µA supply current with Maxim’s AutoShutdown
Plusfeature, which operates when FORCEOFF is high
and a FORCEON is low. When these devices do not
sense a valid signal transition on any receiver and trans-
mitter input for 30sec, the on-board charge pumps are
shut down, reducing supply current to 1µA. This occurs
if the RS-232 cable is disconnected or if the connected
_______________________________________________________________________________________ 9
Share Link: