UNISONIC TECHNOLOGIES CO., LTD UT3243

UNISONIC TECHNOLOGIES CO., LTD
UT3243
CMOS IC
+3.0V TO +5.5V POWER
SUPPLY, 235KBPS,
MULTICHANNAEL RS-232 LINE
DRIVERS/RECEIVERS

DESCRIPTION
The UTC UT3243 consists of 3 drivers and 5 receivers. It meets
ElA/TIA-232 and V.28/V.24 specifications, it intended for notebook
computer applications. A high-efficiency, dual charge-pumps power
supply and a low-dropout transmitter combine to deliver true RS-232
performance from a single +3.0V ~ +5.5V power supply. A
guaranteed data rate of 120kbps provides compatibility with popular
software for communicating with PCs.
The UTC UT3243 achieves 1µA supply current in shutdown condition. When the UT3243 doesn’t detect a valid
signal level on its receiver inputs, the on-board power supply and drivers will shutdown, and when a valid level is
applied to any RS-232 receiver input, then the system turns on again. Therefore, the system saves power without
changes to the existing BIOS or operating system.
The UTC UT3243 requires only 0.1µF capacitors in 3.3V operation, and can operate from input voltages ranging
from +3.0V ~ +5.5V. It is ideal for 3.3V-only systems, 5.0V-only systems, or mixed 3.3V and 5.0V systems that
require true RS-232 performance.
The UTC UT3243 includes one complementary always-active receiver that can monitor an external device (such
as a modem) in shutdown, without forward biasing the protection diodes in a UART that may have VCC completely
removed.

FEATURES
* Operates With 3.0V ~ 5.5V Power Supply
* Three Drivers and Five Receivers
* Operates Up To 235 kbps
* Designed to Transmit at a Data Rate of 235 kbps
* Low Standby Current (1uA Typical)

* External Capacitors (4*0.1µF)
* Accepts 5.0V Logic Input With 3.3V Supply
* Always-Active Non-inverting Receiver Output (R2OUTB)
* Serial-Mouse Drivability
* ESD(HBM) Protected ±8KV(MIN.)
ORDERING INFORMATION
Ordering Number
Lead Free
Halogen Free
UT3243L-P28-T
UT3243G-P28-T
UT3243L-P28-R
UT3243G-P28-R
UT3243L-R28-T
UT3243G-R28-T
UT3243L-R28-R
UT3243G-R28-R
UT3243L-P28-R
Package
Packing
TSSOP-28
TSSOP-28
SSOP-28
SSOP-28
Tube
Tape Reel
Tube
Tape Reel
(1)Packing Type
(1) R: Tape Reel
(2)Package Type
(2) P28: TSSOP-28, R28: SSOP-28
(3)Lead Free
(3) L: Lead Free, G: Halogen Free
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UT3243


CMOS IC
PIN CONFIGURATION
C2+
1
28 C1+
C2-
2
V-
3
27 V+
26 VCC
R1IN
4
R2IN
5
25 GND
24 C1-
R3IN
6
23 FORCEON
R4IN
7
R5IN
8
T1OUT
9
UTC
UT3243
22 FORCEOFF
21 INVALID
20 R2OUTB
T2OUT 10
19 R1OUT
T3OUT 11
T3IN 12
18 R2OUT
17 R3OUT
T2IN 13
16 R4OUT
T1IN 14
15 R5OUT
PIN DESCRIPTION
PIN NO.
1
2
3
4~8
9~11
12~14
15~19
20
PIN NAME
C2+
C2VRXIN
TXOUT
TXIN
RXOUT
R2OUTB
21
INVALID
22
FORCEOFF
23
FORCEON
24
25
26
27
28
C1GND
VCC
V+
C1+
DESCRIPTION
Positive terminal of inverting charge-pump capacitor
Negative terminal of inverting charge-pump capacitor
-5.5V generated by the charge pump
RS-232 Receiver Inputs
RS-232 Transmitter Outputs
TTL/CMOS Transmitter Inputs
TTL/CMOS Receiver Outputs
Noninverting Receiver Output—active in shutdown
Output of the valid signal detector. Indicates if a valid RS-232 level is present on
receiver inputs logic “1”.
Drive low to shut down transmitters and on-board power supply. This over-rides all
automatic circuitry and FORCEON (Table 1).
Drive high to override automatic circuitry keeping transmitters on ( FORCEOFF must
be high) (Table 1).
Negative terminal of the voltage doubler charge-pump capacitor
Ground
+3.0V ~ +5.5V Supply Voltage
+5.5V generated by the charge pump
Positive terminal of the voltage doubler charge-pump capacitor
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UT3243

CMOS IC
BLOCK DIAGRAM
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UT3243

CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
VCC
V+
VVPUMP
RATINGS
UNIT
-0.3~+6
V
-0.3~+7
V
+0.3~-7
V
+13
V
T_IN, FORCEOFF , FORCEON
-0.3~+6
V
Input Voltages
VIN
R_IN
±25
V
T_OUT
±13.2
V
Output Voltages
VOUT
R_OUT, INVALID
-0.3~(VCC+0.3)
V
Short-Circuit Duration
T_OUT
SC
Continuous
696
mW
Power Dissipation(TA = 70°C)
PD
Derating above TA=70°C
8.70
mW/°C
Operating Temperature
TOPR
-40~+85
°C
Storage Temperature
TSTG
-65~+150
°C
Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
2. V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
VCC
V+ (Note 2)
V- (Note 2)
V+ +|V-| (Note 2)

ELECTRICAL CHARACTERISTICS
(VCC = +3.0V~+5.5V, C1~C4=0.1µF (Note 2), TA = TMIN to TMAX, unless otherwise specified)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN TYP
DC CHARACTERISTICS
All R_IN open, FORCEOFF =VCC,
1.0
Supply Current, Shutdown
ISHDN
VCC= 3.3V FORCEON = GND
FORCEOFF = GND
or 5.0V,
1.0
T
=
25°C
A
FORCEON = FORCEOFF = VCC,
Supply Current,
ICC
0.3
Shutdown Disabled
no load
LOGIC INPUTS AND RECEIVER OUTPUTS
T_IN, FORCEON, FORCEOFF
Low
VLGL
Input Logic Threshold
T_IN, EN, FORCEON,
2.0
VCC = 3.3V
High
VLGH
FORCEOFF
VCC = 5.0V
2.4
T_IN, EN, FORCEON, FORCEOFF
Input Leakage Current
IIN(LK)
±0.01
Output Leakage Current
IROUT(LK) Receivers disabled
±0.05
Low
VROUTL IOUT = 1.6mA
Output Voltage
High
VROUTH IOUT = -1.0mA
VCC - 0.6 VCC - 0.1
SHUTDOWN (FORCEON = GND, FORCEOFF = VCC)
Receiver Input
Thresholds to
Transmitters
INVALID
Output
Voltage
Receiver Threshold to
Transmitters Enabled
Enabled
VR(EN)
Disabled
Low
High
VR(DIS)
VINVL
VINVH
tWU
Positive threshold
Negative threshold
1µA supply current, Fig.1
IOUT = 1.6mA
IOUT = -1.0mA
Fig.1
Fig.2
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-2.7
-0.3
VCC - 0.6
250
MAX UNIT
10
µA
10
µA
1
mA
0.8
V
V
±1.0
±10
0.4
µA
µA
V
V
2.7
V
0.3
0.4
V
V
V
µs
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UT3243
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CMOS IC
ELECTRICAL CHARACTERISTICS(Cont.)
(VCC = +3.0V~+5.5V, C1~C4=0.1µF (Note 2), TA = TMIN to TMAX, Unless Otherwise Specified)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
Receiver Positive or
High
tINVH
Negative Threshold to
Fig.2
Low
tINVL
INVALID
RECEIVER INPUTS
Input Voltage Range
VRR
Input Threshold Low
VRINL
TA = 25°C
Input Threshold High
VRINH
TA = 25°C
VCC=3.3V
VCC=5.0V
VCC=3.3V
VCC=5.0V
Input Hysteresis
Input Resistance
TRANSMITTER OUTPUTS
VRINHYS
VRINRES TA = 25°C
Output Voltage Swing
VTOUTSW
Output Resistance
VTOUTRES
Output Short-Circuit Current
Output Leakage Current
MOUSE DRIVABILITY
ITSC
ITOUT(LK) VOUT=±12V, Transmitters disabled
Transmitter Output Voltage
VTOUT
All transmitter outputs loaded with
3kΩ to ground
VCC = V+ = V- = 0V,
Transmitter output = ±2V
T1IN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩ to GND,
T1OUT and T2OUT loaded with 2.5mA each
-25
0.6
0.8
TYP
MAX UNIT
1
µs
30
µs
25
V
3
1.2
1.5
1.5
1.8
0.3
5
±4.8
±5.4
V
300
10M
Ω
±35
V
2.4
2.4
V
V
kΩ
7
±60
±25
mA
µA
±4.8
V
TIMING CHARACTERISTICS
Maximum Data Rate
DR
Receiver Propagation Delay
Receiver Output Time
Enable
Disable
Transmitter Skew
Receiver Skew
Transition-Region Slew Rate
tPHL
tPLH
tR(EN)
tR(DIS)
tTS
tRS
SR
RL = 3kΩ, CL = 1000pF,
one transmitter switching
Receiver input to receiver output,
CL = 150pF
120
Normal operation
|tPHL – tPLH|　|tPHL – tPLH| VCC=3.3V, TA=25°C,
CL = 200pF~2500pF
RL = 3kΩ ~ 7kΩ,
measured from +3V
CL = 200pF~1000pF
~ -3V or -3V ~ +3V
4
235
kbps
0.3
0.3
200
200
200
100
1000
500
8.0
30
µs
ns
ns
ns
ns
V/µs
6
30
Notes: 1. Typical values are at TA = 25°C.
2. C1~C4 = 0.1µF, measured at 3.3V ±10%. C1 = 0.047µF, C2~C4 = 0.33µF, measured at 5.0V ±10%.
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UT3243

CMOS IC
DETAILED DESCRIPTION
Charge-Pump Voltage Converter
The UTC UT3243 consists of a regulated dual charge pumps that provide output voltages of +5.5V and -5.5V,
regardless of the input voltage (VCC) changing from +3.0V to +5.5V.
The charge pumps operate in a discontinuous mode: if the output voltages are less than 5.5V, the charge pumps
are enabled; if the output voltages exceed 5.5V, the charge pumps are disabled.
Each charge pump requires a flying capacitor (C1, C2) and a reservoir capacitor (C3, C4) to generate the V+ and
V- supplies, refer to application circuit.
RS-232 Transmitters
UTC UT3243’s transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232
levels. They guarantee a 120kbps data rate with worst-case loads of 3kΩ in parallel with 1000pF, providing
compatibility with PC-to-PC communication software. Typically, the UTC UT3243 can operate at data rates of
235kbps.
Transmitters can be paralleled to drive multiple receivers or mouse. When FORCEOFF is driven to ground, or
shutdown circuitry senses invalid voltage levels at all receiver inputs, the transmitters are disabled and the outputs
are forced into a high-impedance state.
RS-232 Receivers
The UTC UT3243’s receivers convert RS-232 signals to CMOS-logic output levels. All receivers have one
inverting three-state output. If the receivers is in shutdown, the outputs of receivers are high impedance.
The UTC UT3243 has an always-active complementary output (R2OUTB). R2OUTB is an extra output that monitors
receiver activity while the other receivers are high impedance. This allows Ring Indicator to be monitored without
forward biasing other devices connected to the receiver outputs. This is ideal for systems where VCC is set to 0V in
shutdown to accommodate peripherals.
Table 1.
FORCEOFF Control
Truth Table
T_OUT
R_OUT
R2OUTB
0
High-Z
High-Z
Active
1
Active (Note 3)
Active (Note 3)
Active
Note: 3. If the part is in shutdown mode ( FORCEOFF = VCC, FORCEON = GND), it is shutdown if no valid RS-232
levels are present on all receiver inputs.
FORCEOFF
Shutdown Function
A 1µA supply current is achieved with shutdown feature, which operates when FORCEON is low and FORCEOFF
is high. When the UTC UT3243 senses no valid signal levels on all receiver inputs for 30µs, the on-board power
supply and drivers are shut off, reducing supply current to 1µA. This occurs if the RS-232 cable is disconnected or
the connected peripheral transmitters are turned off. The system turns on again when a valid level is applied to any
RS-232 receiver input. As a result, the system saves power without changes to the existing BIOS or operating
system. INVALID indicates the receiver inputs’ condition, when using shutdown function, the INVALID output is high
when the device is on and low when the device is shut down.
Table 2. Shutdown Logic Control Truth Table
FORCEOFF
RS-232 SIGNAL AT
RECEIVER INPUT
INPUT
Yes
H
No
H
No
H
Yes
L
No
L
FORCEON
INPUT
X
H
L
X
X
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INVALID
OUTPUT
H
L
L
H
L
TRANSCEIVER STATUS
Normal Operation
Normal Operation (Forced On)
Shutdown
Shutdown (Forced Off)
Shutdown (Forced Off)
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CMOS IC
DETAILED DESCRIPTION(Cont.)
Table 2 summarizes the UTC UT3243 operating modes. FORCEON and FORCEOFF override the automatic
circuitry and force the transceiver into its normal operating state or into its low-power standby state. When neither
control is asserted, the IC selects between these states automatically based on receiver input levels.
Transmitters Enabled, INVALID High
+2.7V
Receiver Input Levels
Indeterminate
+0.3V
0V
Shutdown, Transmitters Disabled,
1µA Supply Current, INVALID Low
-0.3V
Indeterminate
-2.7V
Transmitters Enabled, INVALID High
Fig.1 Shutdown Input Levels
When shutdown, the UTC UT3243’s charge pumps are turned off, V+ decays to VCC, V- decays to ground, the
transmitter outputs are disabled (high impedance). The time required to exit shutdown is typically 100µs.
Fig.2 Shutdown Input Timing
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UT3243

CMOS IC
TYPICAL APPLICATION CIRCUIT
3.0V~5.5V
CBYPASS
VCC
C1+
V+
C1
C3
UTC
UT3243
C1C2+
V-
C2
C4
C2T1IN
LOGIC
INPUTS
T2IN
GND
T2OUT
T2
T3IN
VCC
T1OUT
T1
T3OUT
T3
FORCEOFF
INVALID
SHUTDOWN
FORCEON
R2OUTB
RS-232
OUTPUTS
TO POWER
MANAGEMENT
UNIT
R2B
R1OUT
R1IN
R1
5kΩ
R2OUT
LOGIC
OUTPUTS
R2IN
R2
5kΩ
R3OUT
R2IN
R3
5kΩ
R4OUT
RS-232
INPUTS
R4IN
R4
5kΩ
R5OUT
R5IN
R5
5kΩ
GND
Fig.3 Application Circuit
Table 3. Required Capacitor Value
VCC (V)
3.0~3.6
3.15~3.6
4.5~5.5
3.0~5.5
C1 (µF)
0.22
0.1
0.047
0.22
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C2, C3, C4 (µF)
0.22
0.1
0.33
1
CBYPASS (µF)
0.22
0.1
0.047
0.22
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UT3243

CMOS IC
TYPICAL CHARACTERISTICS
Charge-Pump (C1~C4=0.1µF)
C1+
C1+
C1-
C1-
C2+
C2+
C2-
C2-
VCC=3V, OUT=3KΩ
VCC=3V, No Load
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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