5
Detailed Description
The ICL32X7E interface ICs operate from a single +3V to
+5.5V power supply, guarantee a 250kbps minimum data
rate, require only four small external 0.1
F capacitors,
feature low power consumption, and meet all ElA RS-232C
and V.28 specifications. The circuit is divided into three
sections: charge pump, transmitters and receivers.
Charge-Pump
Intersil’s new ICL32XXE family utilizes regulated on-chip
dual charge pumps as voltage doublers, and voltage
inverters to generate
±5.5V transmitter supplies from a VCC
supply as low as 3V. This allows these devices to maintain
RS-232 compliant output levels over the
±10% tolerance
range of 3.3V powered systems. The efficient on-chip power
supplies require only four small, external 0.1
F capacitors
for the voltage doubler and inverter functions at VCC =3.3V.
See the Capacitor Selection section, and Table
3 for
capacitor recommendations for other operating conditions.
The charge pumps operate discontinuously (i.e., they turn off
as soon as the V+ and V- supplies are pumped up to the
nominal values), resulting in significant power savings.
Transmitters
The transmitters are proprietary, low dropout, inverting
drivers that translate TTL/CMOS inputs to EIA/TIA-232
output levels. Coupled with the on-chip
±5.5V supplies,
these transmitters deliver true RS-232 levels over a wide
range of single supply system voltages.
ICL3217E transmitter outputs disable and assume a high
impedance state when the device enters the automatic
powerdown mode. These outputs may be driven to
±12V
when disabled.
Both devices guarantee a 250kbps data rate for full load
conditions (3k
and 1000pF), V
CC ≥ 3.0V, with one
transmitter operating at full speed. Under more typical
conditions of VCC ≥ 3.3V, RL =3k, and CL = 250pF, one
transmitter easily operates at 800kbps.
Transmitter inputs float if left unconnected, and may cause
ICC increases. Connect unused inputs to GND for the best
performance.
Input Hysteresis
25
-
0.3
-
V
Input Resistance
25
357
k
TRANSMITTER OUTPUTS
Output Voltage Swing
All Transmitter Outputs Loaded with 3k
to Ground
Full
±5.0
±5.4
-
V
Output Resistance
VCC = V+ = V- = 0V, Transmitter Output = ±2V
Full
300
10M
-
Output Short-Circuit Current
Full
-
±35
±60
mA
Output Leakage Current
(ICL3217E Only)
VOUT = ±12V, VCC = 0V or 3V to 5.5V
In Automatic Powerdown
Full
-
±25
A
TIMING CHARACTERISTICS
Maximum Data Rate
(One Transmitter Switching)
VCC = 3.15V, C1 - C4 = 0.1F, RL = 3k, CL = 1000pF
Full
250
500
-
kbps
VCC = 3.0V, C1 - C4 = 0.22F, RL = 3k, CL = 1000pF
Full
250
286
-
kbps
VCC ≥ 4.5V, C1 - C4 = 0.1F, RL = 3k, CL = 1000pF
Full
250
310
-
kbps
Receiver Propagation Delay
Receiver Input to Receiver
Output, CL = 150pF
tPHL
25
-
0.3
-
s
tPLH
25
-
0.3
-
s
Transmitter Skew
tPHL - tPLH
Full
-
200
1000
ns
Receiver Skew
tPHL - tPLH
Full
-
100
500
ns
Transition Region Slew Rate
VCC = 3.3V, RL = 3k to 7k,
Measured From +3V to -3V or -3V
to +3V
CL = 200pF to 2500pF
25
4
15
30
V/
s
CL = 200pF to 1000pF
25
6
15
30
V/
s
ESD PERFORMANCE
RS-232 Pins (TOUT, RIN)
IEC61000-4-2, Air-Gap Discharge Method
25
-
±15
-
kV
IEC61000-4-2, Contact Discharge Method
25
-
±8-
kV
Human Body Model
25
-
±15
-
kV
All Other Pins
Human Body Model
25
-
±2-
kV
Electrical Specifications
Test Conditions: VCC = 3V to 5.5V, C1 - C4 = 0.1F; Unless Otherwise Specified.
Typicals are at TA = 25°C (Continued)
PARAMETER
TEST CONDITIONS
TEMP
(°C)
MIN
TYP
MAX
UNITS
ICL3207E, ICL3217E