ISL4241E Intersil Corporation, ISL4241E Datasheet - Page 7

• Manufacturer Part Number: ISL4241E
• Description: QFN Packaged, +/-15kV Esd Protected, +2.7V to +5.5V, 10Nanoamp, 250kbps, RS-232 Transmitters/receivers
• Manufacturer: Intersil Corporation

Powerdown Functionality
The already low current requirement drops significantly
when the device enters powerdown mode. In powerdown,
supply current drops to 10nA, because the on-chip charge
pump turns off (V+ collapses to V
and the transmitter outputs three-state. Inverting receiver
outputs disable only in manual powerdown; refer to Table 2
for details. This micro-power mode makes the ISL424XE
ideal for battery powered and portable applications.
ISL4241E
ISL4243E
RECEIVER
PRESENT
SIGNAL
FIGURE 2. POWER DRAIN THROUGH POWERED DOWN
INPUT?
RS-232
YES
YES
N.A.
N.A.
N.A.
N.A.
NO
NO
NO
AT
POWERED
DOWN
UART
GND
V
CC
PERIPHERAL
FORCEOFF
SHDN OR
INPUT
Rx
Tx
H
H
H
H
H
L
L
L
L
V
CC
SHDN = GND
V
OUT
FORCEON
INPUT
N.A.
N.A.
N.A.
N.A.
= V
7
H
X
X
L
L
CC
CC
TABLE 2. POWERDOWN AND ENABLE LOGIC TRUTH TABLE
, V- collapses to GND),
INPUT
RS-232 CHIP
N.A.
N.A.
N.A.
N.A.
N.A.
EN
H
H
L
L
OLD
V
CURRENT
FLOW
CC
TRANSMITTER
OUTPUTS
High-Z
High-Z
High-Z
High-Z
High-Z
Active
Active
Active
Active
ISL4241E, ISL4243E
RECEIVER
OUTPUTS
High-Z
High-Z
High-Z
High-Z
Active
Active
Active
Active
Active
Software Controlled (Manual) Powerdown
Most devices in the ISL424XE family provide pins that allow
the user to force the IC into the low power, standby state.
On the ISL4241E, the powerdown control is via a simple
shutdown (SHDN) pin. Driving this pin high enables normal
operation, while driving it low forces the IC into it’s
powerdown state. Connect SHDN to V
function isn’t needed. Note that all the receiver outputs
remain enabled during shutdown (see Table 2). For the
lowest power consumption during powerdown, the receivers
FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN
POWERED
OUTPUTS
DOWN
UART
R
Active
Active
Active
Active
Active
Active
Active
Active
Active
OUTB
V
WAKE-UP
CC
LOGIC
TO
R
T
SHDN = GND, EN = V
X
X
FORCEOFF = GND
OUTPUT
INVALID
TRANSITION
DETECTOR
N.A.
N.A.
N.A.
N.A.
H
H
L
L
L
V
OR
OUT
R2
Manual Powerdown
Manual Powerdown w/Rcvr. Disabled
Normal Operation
Normal Operation w/Rcvr. Disabled
Normal Operation
(Auto Powerdown Disabled)
Normal Operation
(Auto Powerdown Enabled)
Powerdown Due to Auto Powerdown
Logic
Manual Powerdown
Manual Powerdown
R2
= HI-Z
V
OUTB
T1
CC
OUT
IN
CC
MODE OF OPERATION
CC
ISL424XE
if the powerdown
R2
T1
OUT
IN