MAX3228EEBV-T ,±15kV ESD-Protected +2.5V to +5.5V RS-232 Transceivers in UCSP and WLPFeatures♦ 6 ✕ 5 Chip-Scale Package (UCSP) and WLPThe MAX3228E/AE and MAX3229E/AE are +2.5V toPackag ..
MAX322CPA ,Precision, Dual-Supply, SPST Analog SwitchesApplicationsMAX320ESA -40°C to +85°C 8 SOBattery-Operated Systems Sample-and-Hold CircuitsMAX320EJA ..
MAX322CSA ,Precision, Dual-Supply, SPST Analog SwitchesGeneral Description ________
MAX322CSA+ ,Precision, Dual Supply, SPST, Analog CMOS SwitchesApplicationsMAX320ESA -40°C to +85°C 8 SOBattery-Operated Systems Sample-and-Hold CircuitsMAX320EJA ..
MAX322CUA ,Precision, Dual-Supply, SPST Analog SwitchesFeaturesThe MAX320/MAX321/MAX322 are precision, dual,' Low On-Resistance, 35Ω max (16Ω typical)SPST ..
MAX322CUA ,Precision, Dual-Supply, SPST Analog SwitchesMAX320/MAX321/MAX32219-0350; Rev 0; 12/94Precision, Dual-Supply, SPST Analog Switches_______________
MAX665CWE ,8V CMOS Switched-Capacitor Voltage Converterapplications.
The MAX665 can also double the output voltage of an
input power supply or battery, ..
MAX665EPA ,8V CMOS Switched-Capacitor Voltage ConverterGeneral Description
The MAX665 charge-pump voltage inverter converts a
+1.5V to +8V input to a ..
MAX665MJA ,8V CMOS Switched-Capacitor Voltage ConverterFeatures
. 0.65V Loss at 100mA Load
. 6.59 Output Impedance
. Pln-Compatlble High-Current ICL766 ..
MAX6660AEE ,Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus InterfaceELECTRICAL CHARACTERISTICS(V = +3V to +5.5V, V = +12V, T = -40°C to +125°C, unless otherwise specif ..
MAX6660AEE ,Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus InterfaceFeatures♦ Integrated Thermal Sensing and Fan-RegulationThe MAX6660 is a remote temperature sensor a ..
MAX6660AEE ,Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus InterfaceApplications+3V TO +5.5VPC0.1μF50ΩNotebooks10kΩTelecom Systems+12VEACHIndustrial Control SystemsSer ..
MAX3228AEEWV+T-MAX3228EEBV-T
±15kV ESD-Protected +2.5V to +5.5V RS-232 Transceivers in UCSP and WLP
General DescriptionThe MAX3228E/AE and MAX3229E/AE are +2.5V to
+5.5V powered EIA/TIA-232 and V.28/V.24 communica-
tions interfaces with low power requirements, high data-
rate capabilities, and enhanced electrostatic discharge
(ESD) protection, in a chip-scale package (UCSP™)
and WLP Package. All transmitter outputs and receiver
inputs are protected to ±15kV using IEC 1000-4-2 Air-
Gap Discharge, ±8kV using IEC 1000-4-2 Contact
Discharge, and ±15kV using the Human Body Model.
The MAX3228E/AE and MAX3229E/AE achieve a 1µA
supply current with Maxim’s AutoShutdown™ feature.
They save power without changes to existing BIOS or
operating systems by entering low-power shutdown
mode when the RS-232 cable is disconnected, or when
the transmitters of the connected peripherals are off.
The transceivers have a proprietary low-dropout trans-
mitter output stage, delivering RS-232 compliant perfor-
mance from a +3.1V to +5.5V supply, and RS-232
compatible performance with a supply voltage as low
as +2.5V. The dual charge pump requires only four
small 0.1µF capacitors for operation from a +3.0V sup-
ply. Each device is guaranteed to run at data rates of
250kbps while maintaining RS-232 output levels.
The MAX3228E/AE and MAX3229E/AE offer a separate
power-supply input for the logic interface, allowing con-
figurable logic levels on the receiver outputs and trans-
mitter inputs. Operating over a +1.65V to VCCrange, VL
provides the MAX3228E/AE and MAX3229E/AE com-
patibility with multiple logic families.
The MAX3229E/AE contains one receiver and one
transmitter. The MAX3228E/AE contains two receivers
and two transmitters. The MAX3228E/AE and
MAX3229E/AE are available in tiny chip-scale and WLP
packaging and are specified across the extended
industrial temperature range of -40°C to +85°C.
ApplicationsPersonal Digital Assistants
Cell Phone Data Lump Cables
Set-Top Boxes
Handheld Devices
Cell Phones
Features6 ✕5 Chip-Scale Package (UCSP) and WLP
PackageESD Protection for RS-232 I/O Pins:
±15kV—IEC 1000-4-2 Air-Gap Discharge
±8kV—IEC 1000-4-2 Contact Discharge
±15kV—Human Body Model1µA Low-Power AutoShutdown250kbps Guaranteed Data RateMeets EIA/TIA-232 Specifications Down to +3.1VRS-232 Compatible to +2.5V Allows Operation
from Single Li+ CellSmall 0.1µF CapacitorsConfigurable Logic Levels
MAX3228E/MAX3228AE/MAX3229E/MAX3229AE
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLPMAX3228E/AE
5kΩ
T2OUTT2IN
TTL/CMOS
INPUTS
C2-
C2+
C1-
C1+A5
20μA20μAB5
VCC
2.5V TO 5.5V
0.1μF
0.1μF
0.1μF
CBYPASS
0.1μF
0.1μF
FORCEOFFFORCEON
INVALID
T1OUTT1IN
GND
TO POWER-
MANAGEMENT
UNIT
RS-232
OUTPUTS
1.65V TO 5.5V
5kΩ
R2INR2OUT
TTL/CMOS
OUTPUTS
R1INR1OUT
RS-232
INPUTS
0.1μF
Typical Operating Circuits19-2139; Rev 2; 10/08
+Denotes a lead-free/RoHS-compliant package.
*Requires solder temperature profile described in the Absolute
Maximum Ratings section.
*UCSP reliability is integrally linked to the user’s assembly meth-
ods, circuit board material, and environment. Refer to the UCSP
Reliabilitly Notice in the UCSP Reliability section of this data
sheet for more information.
T = Tape and reel.
Ordering Information
PARTTEMP RANGEBUMP-PACKAGE
MAX3228EEBV-T-40°C to +85°C6 x 5 UCSP*
MAX3228AEEWV+T-40°C to +85°C6 x 5 WLP
MAX3229EEBV-T-40°C to +85°C6 x 5 UCSP*
MAX3229AEEWV+T-40°C to +85°C6 x 5 WLP
UCSP is a trademark of Maxim Integrated Products, Inc.
AutoShutdown is a trademark of Maxim Integrated Products, Inc.
Typical Operating Circuits continued at end of data sheet.
Pin Configurations appear at end of data sheet.
MAX3228E/MAX3228AE/MAX3229E/MAX3229AE
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
ABSOLUTE MAXIMUM RATINGSStresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VCCto GND...........................................................-0.3V to +6.0V
V+ to GND.............................................................-0.3V to +7.0V
V- to GND..............................................................+0.3V to -7.0V
V+ to |V-| (Note 1)................................................................+13Vto GND..............................................................-0.3V to +6.0V
Input Voltages
T_IN_, FORCEON, FORCEOFFto GND.....-0.3V to (VL+ 0.3V)
R_IN_ to GND...................................................................±25V
Output Voltages
T_OUT to GND...............................................................±13.2V
R_OUT INVALIDto GND............................-0.3V to (VL+ 0.3V)
INVALIDto GND..........................................-0.3V to (VCC+0.3V)
Short-Circuit Duration T_OUT to GND........................Continuous
Continuous Power Dissipation (TA= +70°C)
6 ✕5 UCSP (derate 10.1mW/°C above TA= +70°C)...805mW
6 ✕5 WLP (derate 20mW/°C above TA= +70°C)............1.6W
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Bump Temperature (Soldering) (Note 2)
Infrared (15s)...............................................................+200°C
Vapor Phase (20s).......................................................+215°C
ELECTRICAL CHARACTERISTICS(VCC= +2.5V to +5.5V, VL= +1.65V to +5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%, TA= TMINto TMAX. Typical values are at TA=
+25°C, unless otherwise noted.) (Note 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
DC CHARACTERISTICSVL Input Voltage RangeVL1.65VCC + 0.3V
FORCEON = GND
FORCEOFF = VL, all RIN open10µA
FORCEOFF = GND10µA
VCC Supply Current,
AutoShutdownICC
FORCEON, FORCEOFF floating1mA
VCC Supply Current,
AutoShutdown DisabledICCFORCEON = FORCEOFF = VL
no load0.31mA
FORCEON or FORCEOFF = GND,
VCC = VL =+5V85VL Supply CurrentIL
FORCEON, FORCEOFF floating1
LOGIC INPUTSPullup CurrentsFORCEON, FORCEOFF to VL20µA
Input Logic LowT_IN, FORCEON, FORCEOFF0.4V
Input Logic HighT_IN, FORCEON, FORCEOFF0.66 ✕ VLV
Transmitter Input Hysteresis0.5V
Input Leakage CurrentT_IN±0.01±1µA
RECEIVER OUTPUTSOutput Leakage CurrentsR_OUT, receivers disabled, FORCEOFF =
GND or in AutoShutdown±10µA
Output Voltage LowIOUT = 0.8mA0.4V
Output Voltage HighIOUT = -0.5mAVL - 0.4VL - 0.1V
Note 1:V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
Note 2:This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device
can be exposed to during board level solder attach and rework. This limit permits only the use of the solder profiles recom-
mended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and convection reflow. Pre-
heating is required. Hand or wave soldering is not allowed.
MAX3228E/MAX3228AE/MAX3229E/MAX3229AE
ELECTRICAL CHARACTERISTICS (continued)(VCC= +2.5V to +5.5V, VL= +1.65V to +5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%, TA= TMINto TMAX. Typical values are at TA=
+25°C, unless otherwise noted.) (Note 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
RECEIVER INPUTSInput Voltage Range-25+25V
VCC = +3.3V0.61.2Input Threshold LowTA = +25°CVCC = +5.0V0.81.7V
VCC = +3.3V1.32.4Input Threshold HighTA = +25°CVCC = +5.0V1.82.4V
Input Hysteresis0.5V
Input Resistance357kΩ
AUTO SHUTDOWNPositive threshold2.7Receiver Input Threshold to
INVALID Output HighFigure 3aNegative threshold-2.7V
Receiver Input Threshold to
INVALID Output Low-0.30.3V
Receiver Positive or Negative
Threshold to INVALID HightINVHVCC = +5.0V, Figure 3b1µs
Receiver Positive or Negative
Threshold to INVALID LowtINVLVCC = +5.0V, Figure 3b30µs
Receiver Edge to Transmitters
EnabledtWUVCC = +5.0V, Figure 3b100µs
INVALID OUTPUTOutput Voltage LowIOUT = 0.3mA0.4V
Output Voltage HighIOUT = -0.5mAVCC - 0.4 VCC - 0.1V
TRANSMITTER OUTPUTSVCC Mode Switch Point
(VCC Falling)T_OUT = ±5.0V to ±3.7V2.853.1V
VCC Mode Switch Point
(VCC Rising)T_OUT = ±3.7V to ±5.0V3.33.7VC C M od e S w i tch P oi nt H yster esi s400mV
VCC = +3.1V to
+5.5V, VCC falling
(TA = +25°C)±5.4
Output Voltage Swing
All transmitter
outputs loaded with
3kΩ to ground.VCC = +2.5V to
+3.1V, VCC rising±3.7
Output ResistanceVCC = V+ = V- = 0, T_OUT = ±2V30010MΩ
Output Short-Circuit Current±60mA
Output Leakage CurrentT_OUT = ±12V, transmitters disabled±25µA
ESD PROTECTIONHuman Body Model±15
IEC 1000-4-2 Air-Gap Discharge±15R_IN, T_OUT
IEC 1000-4-2 Contact Discharge±8
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
MAX3228E/MAX3228AE/MAX3229E/MAX3229AE
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
Note 3:VCCmust be greater than VL.
TIMING CHARACTERISTICS(VCC= +2.5V to +5.5V, VL= +1.65V to +5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%, TA= TMINto TMAX. Typical values are at TA=
+25°C, unless otherwise noted.) (Note 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSMaximum Data RateRL = 3kΩ, CL = 1000pF, one transmitter
switching250kbps
Receiver Propagation DelayReceiver input to receiver output,
CL = 150pF0.15μs
Receiver Output Enable-TimeVCC = VL = +5V200ns
Receiver Output Disable-TimeVCC = VL = +5V200ns
Transmitter Skew| tPHL - tPLH |100ns
Receiver Skew| tPHL - tPLH |50ns
Transition Region Slew RateRL = 3kΩ to 7kΩ, CL = 150pF to
1000pF, TA = +25°C630V/μs
Typical Operating Characteristics(VCC= +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩand CL, TA= +25°C, unless otherwise noted.)15002000500100025003000
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCEMAX3228E/28AE/29E/29AE toc01
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
VOH
VOL
VCC RISING25003000
SLEW RATE vs. LOAD CAPACITANCEMAX3228E/28AE/29E/29AE toc02
LOAD CAPACITANCE (pF)
SLEW RATE (V/
VCC = 5.5V
VCC = 2.5V10005001500200025003000
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE (MAX3229E)MAX3228E/28AE/29E/29AE toc03
LOAD CAPACITANCE (pF)
OPERATING SUPPLY CURRENT (mA)
250kbps
20kbps
MAX3228E/MAX3228AE/MAX3229E/MAX3229AE
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
PIN
MAX3228E/
MAX3228AE
MAX3229E/
MAX3229AE
NAMEFUNCTIONA1VCCSupply Voltage. +2.5V to +5.5V supply voltageA2C2+Inverting Charge-Pump Capacitor Positive TerminalA3C2-Inverting Charge-Pump Capacitor Negative TerminalA4V-Negative Charge-Pump Output. -5.5V/-4.0V generated by charge pump.A5VLLogic Voltage Input. Logic-level input for receiver outputs and transmitter inputs.
Connect VL to the system logic supply voltage or VCC if no logic supply is required.
A6, B6A6T_INTransmitter Input(s)B1V+
Positive Charge-Pump Output. +5.5V/+4.0V generated by charge pump. If charge
pump is generating +4.0V, the device has switched from RS-232 compliant to RS-232
compatible mode.
B2, B3, B4,
C2, C3, C4,
D2, D3, D4,
B2, B3, B4,
C2, C3, C4,
D2, D3, D4,
N.C.
No Connection. The MAX3228AE/MAX3229AE are not populated with solder bumps at
these locations. The MAX3228AE/MAX3229AE are populated with electrically isolated
bumps at these locations.B5FORCEONActive-High FORCEON Input. Drive FORCEON high to override automatic circuitry,
keeping transmitters and charge pumps on. Pulls itself high internally if not connected.B6, D6,
E4, E6N.C.No Connection. These locations are populated with solder bumps, but are electrically
isolated.C1C1+Positive Regulated Charge-Pump Capacitor Positive Terminal
Pin Description
Typical Operating Characteristics (continued)(VCC= +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩand CL, TA= +25°C, unless otherwise noted.)
OPERATING SUPPLY CURRENT
vs. SUPPLY VOLTAGE (MAX3229E)
MAX3228E/28AE/29E/29AE toc04
SUPPLY VOLTAGE (V)
OPERATING SUPPLY CURRENT (mA)
TRANSMITTER OUTPUT VOLTAGE vs.
SUPPLY VOLTAGE (VCC RISING)
MAX3228E/28AE/29E/29AE toc05
SUPPLY VOLTAGE (V)
TRANSMITTER OUTPUT VOLTAGE (V)
VOH
VOL
TRANSMITTER OUTPUT VOLTAGE vs.
SUPPLY VOLTAGE (VCC FALLING)
MAX3228E/28AE/29E/29AE toc06
SUPPLY VOLTAGE (V)
TRANSMITTER OUTPUT VOLTAGE (V)
VOH
VOL
MAX3228E/MAX3228AE/MAX3229E/MAX3229AE
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
Detailed Description
Dual-Mode Regulated Charge-Pump
Voltage ConverterThe MAX3228E/AE and MAX3229E/AE internal power
supply consists of a dual-mode regulated charge
pump. For supply voltages above +3.7V, the charge
pump will generate +5.5V at V+ and -5.5V at V-. 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.
For supply voltages below +2.85V, the charge pump
will generate +4.0V at V+ and -4.0V at V-. The charge
pumps operate in a discontinuous mode. If the output
voltages are less than ±4.0V, the charge pumps are
enabled, if the output voltages exceed ±4.0V, 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- supply voltages.
Voltage Generation in the
Switchover RegionThe MAX3228E/AE and MAX3229E/AE include a
switchover circuit between these two modes that have
approximately 400mV of hysteresis around the
switchover point. The hysteresis is shown in Figure 1.
This large hysteresis eliminates mode changes due to
power-supply bounce.
For example, a three-cell NiMh battery system starts at
VCC= +3.6V, and the charge pump will generate an
output voltage of ±5.5V. As the battery discharges, the
PIN
MAX3228E/
MAX3228AE
MAX3229E/
MAX3229AE
NAMEFUNCTIONC5FORCEOFF
Active-Low FORCEOFF Input. Drive FORCEOFF low to shut down transmitters,
receivers, and on-board charge pump. This overrides all automatic circuitry and
FORCEON. Pulls itself high internally if not connected.
C6, D6C6R_OUTReceiver Output(s)D1C1-Positive Regulated Charge-Pump Capacitor Negative TerminalE1GNDGroundE2INVALIDValid Signal Detector Output. INVALID is enabled low if no valid RS-232 level is present
on any receiver input.
E3, E4E3T_OUTRS-232 Transmitter Output(s)
E5, E6E5R_INRS-232 Receiver Input(s)
Pin Description (continued)
SYSTEM SUPPLY (V)VCC (V)VL (V)RS-232 MODE1 Li+ Cell+2.4 to +4.2Regulated System VoltageCompliant/Compatible
3 NiCad/NiMh Cells+2.4 to +3.8Regulated System VoltageCompliant/Compatible
Regulated Voltage Only
(VCC falling)+3.0 to +5.5+3.0 to +5.5Compliant
Regulated Voltage Only
(VCC falling)+2.5 to +3.0+2.5 to +3.0Compatible
Table 1. Operating Supply Options20ms/div
VCC
MAX3228E/MAX3228AE/MAX3229E/MAX3229AEMAX3228E/AE and MAX3229E/AE maintain the outputs
in regulation until the battery voltage drops below +3.1V.
Then the output regulation points change to ±4.0V
When VCCis rising, the charge pump will generate an
output voltage of ±4.0V, while VCCis between +2.5V
and +3.5V. When VCCrises above the switchover volt-
age of +3.5V, the charge pump switches modes to
generate an output of ±5.5V.
Table 1 shows different supply schemes and their oper-
ating voltage ranges.
RS-232 TransmittersThe transmitters are inverting level translators that con-
vert CMOS-logic levels to RS-232 levels. The
MAX3228E/AE and MAX3229E/AE will automatically
reduce the RS-232 compliant levels (±5.5V) to RS-232
compatible levels (±4.0V) when VCCfalls below
approximately +3.1V. The reduced levels also reduce
supply current requirements, extending battery life.
Built-in hysteresis of approximately 400mV for VCC
ensures that the RS-232 output levels do not change if
VCCis noisy or has a sudden current draw causing the
supply voltage to drop slightly. The outputs will return to
RS-232 compliant levels (±5.5V) when VCCrises above
approximately +3.5V.
The MAX3228E/AE and MAX3229E/AE transmitters
guarantee a 250kbps data rate with worst-case loads of
3kΩin parallel with 1000pF.
When FORCEOFFis driven to ground, the transmitters
and receivers are disabled and the outputs become
high impedance. When the AutoShutdown circuitry
senses that all receiver and transmitter inputs are inac-
tive for more than 30µs, the transmitters are disabled
and the outputs go to a high-impedance state. When
the power is off, the MAX3228E/AE and MAX3229E/AE
permit the transmitter outputs to be driven up to ±12V.
The transmitter inputs do not have pullup resistors.
Connect unused inputs to GND or VL.
RS-232 ReceiversThe MAX3228E/AE and MAX3229E/AE receivers con-
vert RS-232 signals to logic output levels. All receivers
have inverting three-state outputs and can be active or
inactive. In shutdown (FORCEOFF= low) or in
AutoShutdown, the MAX3228E/AE and MAX3229E/AE
receivers are in a high-impedance state (Table 3).
The MAX3228E/AE and MAX3229E/AE feature an
INVALIDoutput that is enabled low when no valid
RS-232signal levels have been detected on any
receiver inputs. INVALIDis functional in any mode
(Figures 2 and 3).
Figure 2c. MAX322_E AutoShutdown Logic
FORCEOFFPOWER DOWN
INVALID
FORCEON
INVALID IS AN INTERNALLY GENERATED SIGNAL
THAT IS USED BY THE AUTOSHUTDOWN LOGIC
AND APPEARS AS AN OUTPUT OF THE DEVICE.
POWER DOWN IS ONLY AN INTERNAL SIGNAL.
IT CONTROLS THE OPERATIONAL STATUS OF
THE TRANSMITTERS AND THE POWER SUPPLIES.
VCC
Figure 2a. MAX322_E Entering 1µA Supply Mode via
AutoShutdown
+0.3V
-0.3V
INVALID
TO MAX322 _E
POWER SUPPLY
AND TRANSMITTERSR_IN
*TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1μA IF
ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30μs.
30μs
COUNTER
Figure 2b. MAX322_E with Transmitters Enabled Using
AutoShutdown
+2.7V
-2.7V
INVALID
TO MAX322 _E
POWER SUPPLYR_IN
*TRANSMITTERS ARE ENABLED IF:
ANY RECEIVER INPUT IS GREATER THAN +2.7V OR LESS THAN -2.7V.
ANY RECEIVER INPUT HAS BEEN BETWEEN +0.3V AND -0.3V FOR LESS THAN 30μs.
30μs
COUNTER
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
AutoShutdownThe MAX3228E/AE and MAX3229E/AE achieve a 1µA
supply current with Maxim’s AutoShutdown feature,
which operates when FORCEON is low and FORCEOFF
is high. When these devices sense no valid signal lev-
els on all receiver inputs for 30µs, the on-board charge
pump and drivers are shut off, reducing VCCsupply
current to 1µA. This occurs if the RS-232 cable is dis-
connected or the connected peripheral transmitters are
turned off. The device 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.
Table 3 and Figure 2c summarize the MAX3228E/AE
and MAX3229E/AE operating modes. FORCEON and
FORCEOFFoverride AutoShutdown. When neither con-
trol is asserted, the IC selects between these states
automatically, based on receiver input levels. Figures
2a, 2b, and 3a depict valid and invalid RS-232 receiver
levels. Figures 3a and 3b show the input levels and tim-
ing diagram for AutoShutdown operation.
A system with AutoShutdown may need time to wake
up. Figure 4 shows a circuit that forces the transmitters
on for 100ms, allowing enough time for the other
system to realize that the MAX3228E/AE and
MAX3229E/AE are active. If the other system transmits
valid RS-232 signals within that time, the RS-232 ports
on both systems remain enabled.
When shut down, the device’s charge pumps are off,
V+ is pulled to VCC, V- is pulled to ground, and the
transmitter outputs are high-impedance. The time
required to exit shutdown is typically 100µs (Figure 3b).
FORCEON and FORCEOFFIn case FORCEON and FORCEOFFare inaccessible,
these pins have 60kΩ(typ) pullup resistors connected to(Table 2). Therefore, if FORCEON and FORCEOFFare
not connected, the MAX3228E/AE and MAX3229E/AE
will always be active. Pulling these pins to ground will
draw current from the VLsupply. This current can be cal-
culated from the voltage supplied at VLand the 60kΩ
(typ) pullup resistor.
Logic Supply InputUnlike other RS-232 interface devices, where the
receiver outputs swing between 0 and VCC, the
MAX3228E/MAX3228AE/MAX3229E/MAX3229AE
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLPFigure 3. AutoShutdown Trip Levels
VCC
VCC
tINVL
tWU
INVALID
REGION
RECEIVER
INPUT
VOLTAGE
(V)
INVALID
OUTPUT
(V)
tINVH
TRANSMITTERS ENABLED, INVALID HIGHRECEIVER INPUT LEVELS
AUTOSHUTDOWN, TRANSMITTERS DISABLED,
1μA SUPPLY CURRENT, INVALID LOW
TRANSMITTERS ENABLED, INVALID HIGH-2.7V
-0.3V
+2.7V
+0.3V
INDETERMINATE
INDETERMINATE
Figure 4. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System
FORCEON
MASTER SHDN LINE
0.1μF1MΩ
FORCEOFF
MAX3228E/AE
MAX3229E/AE
POWER-
MANAGEMENT
UNIT
PIN NAMEPOWER-ON DEFAULTMECHANISMFORCEONHighInternal pullup
FORCEOFFHighInternal pullup
Table 2. Power-On Default States
