FN6041 Rev 2.00 Page 1 of 13
June 16, 2010
FN6041
Rev 2.00
June 16, 2010
ISL4270E
QFN Packaged, ±15kV ESD Protected, +3V to +5.5V, 300nA, 250kbps, RS-232
Transceivers with Enhanced Automatic Powerdown and a Separate Logic Supply
DATASHEET
The Intersil ISL4270E is a 3.0V to 5.5V powered RS-232
transceiver which meets ElA/TIA-232 and V.28/V.24
specifications, even at VCC = 3.0V. Additionally, it provides
15kV ESD protection (IEC61000-4-2 Air Gap and Human
Body Model) on transmitter outputs and receiver inputs
(RS-232 pins). Targeted applications are PDAs, Palmtops,
and notebook and laptop computers where the low
operational, and even lower standby power consumption is
critical. Efficient on-chip charge pumps, coupled with manual
and enhanced automatic powerdown functions, reduce the
standby supply current to a 300nA trickle. Tiny 5mmx5mm
Quad Flat No-Lead (QFN) packaging, and the use of small,
low value capacitors ensure board space savings as well.
Data rates greater than 250kbps are guaranteed at worst
case load conditions.
The ISL4270E features a VL pin that adjusts the logic pin
output levels and input thresholds to values compatible with
the VCC powering the external logic (e.g., a UART).
This device includes an enhanced automatic powerdown
function which powers down the on-chip power-supply and
driver circuits. This occurs when all receiver and transmitter
inputs detect no signal transitions for a period of 30 seconds.
It power back up, automatically, whenever it senses a
transition on any transmitter or receiver input.
Table 1 summarizes the features of the ISL4270E, while
Application Note AN9863 summarizes the features of each
device comprising the 3V RS-232 family.
Features
• Available in Near Chip Scale QFN (5mmx5mm) Package
•V
L Supply Pin for Compatibility with Mixed Voltage
Systems
• ESD Protection for RS-232 I/O Pins to 15kV (IEC61000)
• Manual and Enhanced Automatic Powerdown Features
• Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V
• On-Chip Charge Pumps Require Only Four External
0.1F Capacitors
• Receivers Stay Active in Powerdown
• Very Low Supply Current . . . . . . . . . . . . . . . . . . . . 300A
• Guaranteed Minimum Data Rate . . . . . . . . . . . . . 250kbps
• Wide Power Supply Range . . . . . . . Single +3V to +5.5V
• Low Supply Current in Powerdown State. . . . . . . . 300nA
• Pb-Free (RoHS Compliant)
Applications
• Any System Requiring RS-232 Communication Ports
- Battery Powered, Hand-Held, and Portable Equipment
- Laptop Computers, Notebooks, Palmtops
- Digital Cameras
- PDA’s and PDA Cradles
- Cellular/Mobile Phones
Ordering Information
PART NUMBER
(Note)
PART
MARKING
TEMP.
RANGE
(°C) PACKAGE
PKG.
DWG. #
ISL4270EIRZ* ISL4270 EIRZ -40 to +85 32 Ld QFN
(Pb-free)
L32.5x5B
*Add “-T” suffix for tape and reel. Please refer to TB347 for details on
reel specifications.
NOTE: These Intersil Pb-free plastic packaged products employ
special Pb-free material sets, molding compounds/die attach
materials, and 100% matte tin plate plus anneal (e3 termination
finish, which is RoHS compliant and compatible with both SnPb and
Pb-free soldering operations). Intersil Pb-free products are MSL
classified at Pb-free peak reflow temperatures that meet or exceed
the Pb-free requirements of IPC/JEDEC J STD-020.
TABLE 1. SUMMARY OF FEATURES
PART NUMBER
NO. OF
Tx.
NO. OF
Rx.
DATA RATE
(kbps)
Rx. ENABLE
FUNCTION?
VL LOGIC
SUPPLY PIN?
MANUAL
POWER- DOWN?
ENHANCED AUTOMATIC
POWERDOWN FUNCTION?
ISL4270E 3 3 250 NO YES YES YES
ISL4270E
FN6041 Rev 2.00 Page 2 of 13
June 16, 2010
Pinout
ISL4270E (QFN)
TOP VIEW
NC
C2+
C2-
V-
T1IN
T2IN
INVALID
T1OUT
T2OUT
T3OUT
R1IN
R2IN
R3IN
NC
NC
T3IN
FORCEON
R3OUT
R2OUT
VL
R1OUT
C1-
V+
C1+
FORCEOFF
VCC
NC
GND
NC
7
11 12 13 14 15910
6
1
2
3
4
5
8
16
18
19
24
23
22
21
20
17
2728293031 252632
NC
NC
NC
PD
Pin Descriptions
PIN FUNCTION
VCC System power supply input (3.0V to 5.5V).
V+ Internally generated positive transmitter supply (+5.5V).
V- Internally generated negative transmitter supply (-5.5V).
GND Ground connection. This is also the potential of the thermal pad (PD).
C1+ External capacitor (voltage doubler) is connected to this lead.
C1- External capacitor (voltage doubler) is connected to this lead.
C2+ External capacitor (voltage inverter) is connected to this lead.
C2- External capacitor (voltage inverter) is connected to this lead.
TIN TTL/CMOS compatible transmitter Inputs. The switching point is a function of the VL voltage.
TOUT 15kV ESD Protected, RS-232 level (nominally 5.5V) transmitter outputs.
RIN 15kV ESD Protected, RS-232 compatible receiver inputs.
ROUT TTL/CMOS level receiver outputs. Swings between GND and VL.
VLLogic-Level Supply. All TTL/CMOS inputs and outputs are powered by this supply.
INVALID Active low output that indicates if no valid RS-232 levels are present on any receiver input. Swings between GND and VL.
FORCEOFF Active low to shut down transmitters and on-chip power supply. This overrides any automatic circuitry and FORCEON (see Table 2).
The switching point is a function of the VL voltage.
FORCEON Active high input to override automatic powerdown circuitry thereby keeping transmitters active (FORCEOFF must be high). The
switching point is a function of the VL voltage.
PD Exposed Thermal Pad. Connect to GND.
ISL4270E
FN6041 Rev 2.00 Page 3 of 13
June 16, 2010
Typical Operating Circuit
27
VCC
T1OUT
T2OUT
T3OUT
T1IN
T2IN
T3IN
T1
T2
T3
0.1F
+0.1F
+
0.1F
5
6
23
22
10 21
29
31
30
4
V+
V-
C1+
C1-
C2+
C2-
+
0.1F
2
3
R1OUT R1IN
20
5k
R2OUT R2IN
19
13
5k
R3OUT R3IN
18
12
5k
14
C1
C2
+C3
C4
FORCEON
FORCEOFF
11
GND
28
+3.3V +0.1F
26
VCC
TTL/CMOS
LOGIC LEVELS
RS-232
LEVELS
RS-232
LEVELS
R1
R2
R3
7
INVALID
TO POWER
CONTROL LOGIC
VL
15
LOGIC VCC +
0.1F
