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19-2140; Rev 0; 8/01
+2.5V to +5.5V RS-232 Transceivers in UCSP
General Description
The MAX3228/MAX3229 are +2.5V to +5.5V powered EIA/TIA-232 and V.28/V.24 communications interfaces with low power requirements, and high data-rate capabilities, in a chip-scale package (UCSPTM). The MAX3228/MAX3229 achieve a 1A supply current with Maxim's AutoShutdownTM 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 transmitter output stage, delivering RS-232 compliant performance 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 0.1F capacitors for operation from a +3.0V supply. Each device is guaranteed to run at data rates of 250kbps while maintaining RS-232 output levels. The MAX3228/MAX3229 offer a separate power-supply input for the logic interface, allowing configurable logic levels on the receiver outputs and transmitter inputs. Operating over a +1.65V to VCC range, VL provides the MAX3228/MAX3229 compatibility with multiple logic families. The MAX3229 contains one receiver and one transmitter. The MAX3228 contains two receivers and two transmitters. The MAX3228/MAX3229 are available in tiny chip-scale packaging and are specified across the extended industrial temperature range of -40C to +85C. o 6 5 Chip-Scale Packaging (UCSP) o 1A Low-Power AutoShutdown o 250kbps Guaranteed Data Rate o Meets EIA/TIA-232 Specifications Down to +3.1V o RS-232 Compatible to +2.5V Allows Operation from Single Li+ Cell o Small 0.1F Capacitors o Configurable Logic Levels
Features
MAX3228/MAX3229
Ordering Information
PART MAX3228EBV MAX3229EBV TEMP. RANGE -40C to +85C -40C to +85C PINPACKAGE 6 5 UCSP* 6 5 UCSP*
*Requires solder temperature profile described in the Absolute Maximum Ratings section. *UCSP reliability is integrally linked to the user's assembly methods, circuit board material, and environment. Refer to the UCSP Reliabilitly Notice in the UCSP Reliability section of this data sheet for more information.
Typical Operating Circuits
2.5V TO 5.5V 1.65V TO 5.5V 0.1F CBYPASS 0.1F A1 C1 C1+ C1C2+ C2VL T1OUT VL B6 T2IN VL D6 R1OUT R1IN E6 T2OUT E4 E3 RS-232 OUTPUTS VCC A5 VL V+ B1 C3 0.1F A4 C4 0.1F
Applications
Personal Digital Assistants Cell Phone Data Lump Cables Set-Top Boxes Hand-Held Devices Cell Phones
C1 0.1F
D1 A2
MAX3228
V-
C2 0.1F
A3
A6 T1IN TTL/CMOS INPUTS
Typical Operating Circuits continued at end of data sheet. Pin Configurations appear at end of data sheet.
TTL/CMOS OUTPUTS C6 R2OUT
VL
5k R2IN E5
RS-232 INPUTS
5k
UCSP is a trademark of Maxim Integrated Products, Inc. AutoShutdown is a trademark of Maxim Integrated Products, Inc.
20A B5 FORCEON
VL
VL INVALID 20A E2
TO POWERMANAGEMENT UNIT VL
FORCEOFF C5 GND E1
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
ABSOLUTE MAXIMUM RATINGS
VCC to 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) ................................................................+13V VL to GND..............................................................-0.3V to +6.0V Input Voltages T_IN, FORCEON, FORCEOFF to GND .......-0.3V to (VL + 0.3V) R_IN to GND .....................................................................25V Output Voltages T_OUT to GND ...............................................................13.2V R_OUT to GND ...........................................-0.3V to (VL + 0.3V) INVALID to GND......................................-0.3V to (VCC + 0.3V) Short-Circuit Duration T_OUT to GND........................Continuous Continuous Power Dissipation (TA = +70C) 6 5 UCSP (derate 10.1mW/C above TA = +70C) ...805mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Bump Temperature (Soldering) (Note 2) Infrared (15s) ...............................................................+200C Vapor Phase (20s) .......................................................+215C
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 recommended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and convection reflow. Preheating is required. Hand or wave soldering is not allowed.
Stresses 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.
ELECTRICAL CHARACTERISTICS
(VCC = +2.5V to +5.5V, VL = +1.65V to +5.5V, C1-C4 = 0.1F, tested at +3.3V 10%, TA = TMIN to TMAX. Typical values are at TA = +25C, unless otherwise noted.) (Note 3)
PARAMETER DC CHARACTERISTICS VL Input Voltage Range VCC Supply Current, AutoShutdown VL FORCEON = GND FORCEOFF = VL, all RIN open FORCEOFF = GND FORCEON, FORCEOFF floating VCC Supply Current, AutoShutdown Disabled VL Supply Current LOGIC INPUTS Pullup Currents Input Logic Low Input Logic High Transmitter Input Hysteresis Input Leakage Current RECEIVER OUTPUTS Output Leakage Currents Output Voltage Low Output Voltage High R_OUT, receivers disabled, FORCEOFF = GND or in AutoShutdown IOUT = 0.8mA IOUT = -0.5mA VL - 0.4 VL - 0.1 10 0.4 A V V T_IN FORCEON, FORCEOFF to VL T_IN, FORCEON, FORCEOFF T_IN, FORCEON, FORCEOFF 0.66 VL 0.5 0.01 1 20 0.4 A V V V A ICC FORCEON = FORCEOFF = VL no load FORCEON or FORCEOFF = GND, VCC = VL = +5v FORCEON, FORCEOFF floating 0.3 85 1 1.65 VCC + 0.3 10 10 1 1 V A A mA mA SYMBOL CONDITIONS MIN TYP MAX UNITS
ICC
IL
A
2
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+2.5V to +5.5V RS-232 Transceivers in UCSP
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +2.5V to +5.5V, VL = +1.65V to +5.5V, C1-C4 = 0.1F, tested at +3.3V 10%, TA = TMIN to TMAX. Typical values are at TA = +25C, unless otherwise noted.) (Note 3)
PARAMETER RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance AUTOSHUTDOWN Receiver Input Threshold to INVALID Output High Receiver Input Threshold to INVALID Output Low Receiver Positive or Negative Threshold to INVALID High Receiver Positive or Negative Threshold to INVALID Low Receiver Edge to Transmitters Enabled TRANSMITTER OUTPUTS VCC Mode Switch Point (VCC Falling) VCC Mode Switch Point (VCC Rising) VCC Mode Switch Point Hysteresis All transmitter outputs loaded with 3k to ground. VCC = +3.1V to +5.5V, VCC falling VCC = +2.5V to +2.9V 5 3.7 300 10M 60 T_OUT = 12V, transmitters disabled IOUT = 0.8mA IOUT = -0.5mA VCC - 0.4 VCC - 0.1 25 0.4 mA A V V T_OUT = 5.0V to 3.7V T_OUT = 3.7V to 5.0V 2.85 3.3 400 5.4 V 3.1 3.7 V V mV tINVH tINVL tWU VCC = +5.0V, Figure 3b VCC = +5.0V, Figure 3b VCC = +5.0V, Figure 3b Figure 3a Positive threshold Negative threshold -2.7 -0.3 1 30 100 0.3 2.7 V V s s s 3 TA = +25C TA = +25C VCC = 3.3V VCC = 5.0V VCC = 3.3V VCC = 5.0V -25 0.6 0.8 1.2 1.7 1.3 1.8 0.5 5 7 2.4 2.4 +25 V V V V k SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX3228/MAX3229
Output Voltage Swing
Output Resistance Output Short-Circuit Current Output Leakage Current INVALID OUTPUT Output Voltage Low Output Voltage High
VCC = V+ = V- = 0, T_OUT = 2V
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+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
TIMING CHARACTERISTICS
(VCC = +2.5V to +5.5V, VL = +1.65V to +5.5V, C1-C4 = 0.1F, tested at +3.3V 10%, TA = TMIN to TMAX. Typical values are at TA = +25C, unless otherwise noted.) (Note 3)
PARAMETER Maximum Data Rate Receiver Propagation Delay Receiver Output Enable-Time Receiver Output Disable-Time Transmitter Skew Receiver Skew Transition Region Slew Rate | tPHL - tPLH | | tPHL - tPLH | RL = 3k to 7k, CL = 150pF to 1000pF, TA = +25C 6 SYMBOL CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching Receiver input to receiver output, CL = 150pF VCC = VL= +5V VCC = VL= +5V MIN 250 0.15 200 200 100 50 30 TYP MAX UNITS kbps s ns ns ns ns V/s
Note 3: VCC must be greater than VL.
Typical Operating Characteristics
(VCC = +3.3V, 250kbps data rate, 0.1F capacitors, all transmitters loaded with 3k and CL, TA = +25C, unless otherwise noted.)
TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3228/9 toc01
SLEW RATE vs. LOAD CAPACITANCE
MAX3228/9 toc02
OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE (MAX3229)
OPERATING SUPPLY CURRENT (mA) 18 16 14 12 10 8 6 4 2 0 20kbps 0 500 1000 1500 2000 2500 3000 250kbps
MAX3228/9 toc03
6 VCC RISING TRANSMITTER OUTPUT VOLTAGE (V) 4 2 0 -2 -4 -6 0 500 1000 1500 2000 2500 VOL VOH
30 25 SLEW RATE (V/s) 20 15 10 5 0 VCC = 2.5V VCC = 5.5V
20
3000
0
500
1000
1500
2000
2500
3000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
4
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+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
Typical Operating Characteristics (continued)
(VCC = +3.3V, 250kbps data rate, 0.1F capacitors, all transmitters loaded with 3k and CL, TA = +25C, unless otherwise noted.)
OPERATING SUPPLY CURRENT vs. SUPPLY VOLTAGE (MAX3229)
MAX3228/9 toc04
TRANSMITTER OUTPUT VOLTAGE vs. SUPPLY VOLTAGE (VCC RISING)
MAX3228/9 toc05
TRANSMITTER OUTPUT VOLTAGE vs. SUPPLY VOLTAGE (VCC FALLING)
TRANSMITTER OUTPUT VOLTAGE (V) 8 6 4 2 0 -2 -4 -6 -8 VOL VOH
MAX3228/9 toc06
20 OPERATING SUPPLY CURRENT (mA) 18 16 14 12 10 8 6 4 2 0 2.5 3.0 3.5 4.0 4.5 5.0
10 TRANSMITTER OUTPUT VOLTAGE (V) 8 6 4 2 0 -2 -4 -6 -8 VOL VOH
10
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Pin Description
PIN MAX3228 A1 A2 A3 A4 A5 A6, B6 B1 B2, B3, B4, C2, C3, C4, D2, D3, D4, D5 B5 -- C1 MAX3229 A1 A2 A3 A4 A5 A6 B1 B2, B3, B4, C2, C3, C4, D2, D3, D4, D5 B5 B6, D6, E4, E6 C1 NAME VCC C2+ C2VVL T_IN V+ +2.5V to +5.5V Supply Voltage Positive Terminal of Inverting Charge-Pump Capacitor Negative Terminal of Inverting Charge-Pump Capacitor -5.5V/-4.0V Generated by Charge Pump 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. Transmitter Input(s) +5.5V/+4.0V Generated by Charge Pump. If charge pump is generating +4.0V, the part has switched from RS-232 compliant to RS-232 compatible mode. FUNCTION
N.C.
No Connection. These locations are not populated with solder bumps.
FORCEON N.C. C1+
FORCEON Input, Active-High. Drive FORCEON high to override automatic circuitry, keeping transmitters and charge pumps on. Pulls itself high internally if not connected. No Connection. These locations are populated with solder bumps, but are electrically isolated. Positive Terminal of Positive Regulated Charge-Pump Capacitor
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+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
Pin Description (continued)
PIN MAX3228 C5 C6, D6 D1 E1 E2 E3, E4 E5, E6 MAX3229 C5 C6 D1 E1 E2 E3 E5 NAME FUNCTION FORCEOFF Input, Active-Low. 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. Receiver Output(s) Negative Terminal of Positive Regulated Charge-Pump Capacitor. Ground Output of Valid Signal Detector. INVALID is enabled low if no valid RS-232 level is present on any receiver input. RS-232 Transmitter Output(s) RS-232 Receiver Input(s)
FORCEOFF R_OUT C1GND INVALID T_OUT R_IN
Table 1. Operating Supply Options
SYSTEM SUPPLY (V) 1 Li+ Cell 3 NiCad/NiMH Cells Regulated Voltage Only (VCC falling) Regulated Voltage Only (VCC falling) VCC (V) +2.4 to +4.2 +2.4 to +3.8 +3.0 to +5.5 +2.5 to +3.0 VL (V) Regulated System Voltage Regulated System Voltage +3.0 to +5.5 +2.5 to +3.0 RS-232 MODE Compliant/Compatible Compliant/Compatible Compliant Compatible
Detailed Description
Dual-Mode Regulated Charge-Pump Voltage Converter
The MAX3228/MAX3229 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 Region
The MAX3228/MAX3229 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.
VCC
4V
0 V+ 6V
0 20ms/div
Figure 1. V+ Switchover for Changing VCC 6 _______________________________________________________________________________________
+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
+0.3V TO MAX322 _ POWER SUPPLY AND TRANSMITTERS INVALID -2.7V +2.7V TO MAX322 _ POWER SUPPLY INVALID
R_IN
R_IN
-0.3V
30s COUNTER R
30s COUNTER R
*TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1A IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30s.
*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 30s.
Figure 2a. MAX322_ Entering 1A Supply Mode via AutoShutdown
Figure 2b. MAX322_ with Transmitters Enabled Using AutoShutdown
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 MAX3228/MAX3229 maintain the outputs in regulation until the battery voltage drops below +3.1V. Then the output regulation points change to 4.0V When VCC is rising, the charge pump will generate an output voltage of 4.0V, while VCC is between +2.5V and +3.5V. When VCC rises above the switchover voltage of +3.5V, the charge pump switches modes to generate an output of 5.5V. Table 1 shows different supply schemes and their operating voltage ranges.
the power is off, the MAX3228/MAX3229 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 Receivers
The MAX3228/MAX3229 receivers convert 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 MAX3228/MAX3229 receivers are in a high-impedance state (Table 3). The MAX3228/MAX3229 feature an INVALID output that is enabled low when no valid RS-232 signal levels have been detected on any receiver inputs. INVALID is functional in any mode (Figures 2 and 3).
RS-232 Transmitters
The transmitters are inverting level translators that convert CMOS-logic levels to RS-232 levels. The MAX3228/MAX3229 will automatically reduce the RS232 compliant levels (5.5V) to RS-232 compatible levels (4.0V) when VCC falls 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 VCC is 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 VCC rises above approximately +3.5V. The MAX3228/MAX3229 transmitters guarantee a 250kbps data rate with worst-case loads of 3k in parallel with 1000pF. When FORCEOFF is 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 inactive for more than 30s, the transmitters are disabled and the outputs go to a high-impedance state. When
VL
FORCEOFF VL VCC FORCEON INVALID
POWER DOWN
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.
Figure 2c. MAX322_ AutoShutdown Logic 7
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+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
AutoShutdown
TRANSMITTERS ENABLED, INVALID HIGH RECEIVER INPUT LEVELS +2.7V INDETERMINATE +0.3V 0 -0.3V INDETERMINATE -2.7V TRANSMITTERS ENABLED, INVALID HIGH AUTOSHUTDOWN, TRANSMITTERS DISABLED, 1A SUPPLY CURRENT, INVALID LOW
a)
RECEIVER INPUT VOLTAGE (V)
INVALID REGION
VCC INVALID OUTPUT (V) 0
tINVL
tINVH tWU
V+ VCC 0 V-
The MAX3228/MAX3229 achieve a 1A supply current with Maxim's AutoShutdown feature, which operates when FORCEON is low and FORCEOFF is high. When these devices sense no valid signal levels on all receiver inputs for 30s, the on-board charge pump and drivers are shut off, reducing VCC supply current to 1A. This occurs if the RS-232 cable is disconnected 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 MAX3228/ MAX3229 operating modes. FORCEON and FORCEOFF override AutoShutdown. When neither control 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 timing 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 MAX3228/MAX3229 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 devices' 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 100s (Figure 3b).
b)
FORCEON and FORCEOFF
In case FORCEON and FORCEOFF are inaccessible, these pins have 60 (typ) pullup resistors connected to VL (Table 2). Therefore, if FORCEON and FORCEOFF are not connected, the MAX3228 and MAX3229 will always be active. Pulling these pins to ground will draw current from the VL supply. This current can be calculated from the voltage supplied at VL and the 60k (typ) pullup resistor.
Figure 3. AutoShutdown Trip Levels
POWERMANAGEMENT UNIT
MASTER SHDN LINE 0.1F 1M
FORCEOFF FORCEON
VL Logic Supply Input
Unlike other RS-232 interface devices, where the receiver outputs swing between 0 and V CC , the
MAX3228 MAX3229
Table 2. Power-On Default States
Figure 4. AutoShutdown with Initial Turn-On to Wake Up a System
PIN NAME FORCEON FORCEOFF POWER-ON DEFAULT High High MECHANISM Internal pullup Internal pullup
8
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+2.5V to +5.5V RS-232 Transceivers in UCSP
Table 3. Output Control Truth Table
TRANSCEIVER STATUS Shutdown (AutoShutdown) Shutdown (Forced Off) Normal Operation (Forced On) Normal Operation (AutoShutdown) FORCEON Low X High Low FORCEOFF High Low High High RECEIVER STATUS High-Z High-Z Active Active INVALID L H
MAX3228/MAX3229
X = Don't care. = INVALID output state is determined by R_IN input levels.
MAX3228/MAX3229 feature a separate logic supply input (VL) that sets VOH for the receiver and INVALID outputs. The transmitter inputs (T_IN), FORCEON and FORCEOFF, are also referred to VL. This feature allows maximum flexibility in interfacing to different systems and logic levels. Connect VL to the system's logic supply voltage (+1.65V to +5.5V), and bypass it with a 0.1F capacitor to GND. If the logic supply is the same as VCC, connect VL to VCC. Always enable VCC before enabling the VL supply. VCC must be greater than or equal to the VL supply.
Software-Controlled Shutdown
If direct software control is desired, connect FORCEOFF and FORCEON together to disable AutoShutdown. The microcontroller then drives FORCEOFF and FORCEON like a SHDN input, INVALID can be used to alert the microcontroller to indicate serial data activity.
transmitter outputs and slightly reduces power consumption. C2, C3, and C4 can be increased without changing C1's value. However, do not increase C1 without also increasing the values of C2, C3, and C4 to maintain the proper ratios (C1 to the other capacitors). When using the minimum required capacitor values, make sure the capacitor value does not degrade excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor's equivalent series resistance (ESR) usually rises at low temperatures and influences the amount of ripple on V+ and V-.
Power-Supply Decoupling
In most circumstances, a 0.1F VCC bypass capacitor is adequate. In applications that are sensitive to powersupply noise, use a capacitor of the same value as the charge-pump capacitor C1. Connect bypass capacitors as close to the IC as possible.
Applications Information
Capacitor Selection
The capacitor type used for C1-C4 is not critical for proper operation; either polarized or nonpolarized capacitors may be used. However, ceramic chip capacitors with an X7R or X5R dielectric work best. The charge pump requires 0.1F capacitors for 3.3V operation. For other supply voltages, refer to Table 4 for required capacitor values. Do not use values smaller than those listed in Table 4. Increasing the capacitor values (e.g., by a factor of 2) reduces ripple on the
5V/div FORCEON = FORCEOFF 0
2V/div
Table 4. Required Capacitor Values
TOUT
VCC (V) 2.5 to 3.0 3.0 to 3.6 4.5 to 5.5 3.0 to 5.5
C1, CBYPASS (F) 0.22 0.1 0.047 0.22
C2, C3, C4 (F) 0.22 0.1 0.33 1
4s/div
0
Figure 5. Transmitter Outputs Exiting Shutdown or Powering Up
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+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
VCC 0.1F C1+ C1 C1C2+ C2 C2T1IN VL R1OUT R1IN VL T1OUT 1000pF 4s/div VCC VL V+ C3 T_OUT 0 -5V VC4 R_OUT 5V 0 VL 5V 0.1F T_IN 0 5V
MAX3229
Figure 7. Loopback Test Result at 120kbps
5k 5V INVALID FORCEON GND FORCEOFF TO POWERMANAGEMENT UNIT VL T_OUT T_IN 0 5V 0 -5V 5V R_OUT 0 4s/div
Figure 6. Transmitter Loopback Test Circuit
Transmitter Outputs when Exiting Shutdown
Figure 5 shows a transmitter output when exiting shutdown mode. The transmitter is loaded with 3k in parallel with 1000pF. The transmitter output displays no ringing or undesirable transients as it comes out of shutdown, and is enabled only when the magnitude of V- exceeds approximately -3V.
Figure 8. Loopback Test Result at 250kbps
High Data Rates
The MAX3228/MAX3229 maintain the RS-232 5.0V minimum transmitter output voltage even at high data rates. Figure 6 shows a transmitter loopback test cir-
cuit. Figure 7 shows a loopback test result at 120kbps, and Figure 8 shows the same test at 250kbps. For Figure 7, the transmitter was driven at 120kbps into an RS-232 load in parallel with 1000pF. For Figure 8, a single transmitter was driven at 250kbps, and loaded with an RS-232 receiver in parallel with 1000pF.
10
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+2.5V to +5.5V RS-232 Transceivers in UCSP
Table 5. Reliability Test Data
TEST Temperature Cycle Operating Life Moisture Resistance Low-Temperature Storage Low-Temperature Operational Solderability ESD High-Temperature Operating Life CONDITIONS -35C to +85C, -40C to +100C TA = +70C +20C to +60C, 90% RH -20C -10C 8hr steam age 2000V, Human Body Model TJ = +150C DURATION 150 cycles, 900 cycles 240hr 240hr 240hr 24hr -- -- 168hr NO. OF FAILURES PER SAMPLE SIZE 0/10, 0/200 0/10 0/10 0/10 0/10 0/15 0/5 0/45
MAX3228/MAX3229
Typical Operating Circuits (continued)
2.5V TO 5.5V 1.65V TO 5.5V CBYPASS 0.1F A1 C1 C1 0.1F D1 A2 C2 0.1F A3 C1+ C1C2+ C2VL T1OUT VL C6 R1OUT R1IN E5 E3 RS-232 VCC A5 VL V+ B1 C3 0.1F A4 C4 0.1F 0.1F
UCSP Reliability
The UCSP represents a unique packaging form factor that may not perform equally to a packaged product through traditional mechanical reliability tests. CSP reliability is integrally linked to the user's assembly methods, circuit board material, and usage environment. The user should closely review these areas when considering use of a CSP package. Performance through Operating Life Test and Moisture Resistance remains uncompromised as it is primarily determined by the wafer-fabrication process. Mechanical stress performance is a greater consideration for a CSP package. CSPs are attached through direct solder contact to the user's PC board, foregoing the inherent stress relief of a packaged product lead frame. Solder joint contact integrity must be considered. Table 5 shows the testing done to characterize the CSP reliability performance. In conclusion, the UCSP is capable of performing reliably through environmental stresses as indicated by the results in the table. Additional usage data and recommendations are detailed in the UCSP application note, which can be found on Maxim's website at www.maxim-ic.com.
MAX3229
V-
A6 T1IN TTL/CMOS
5k VL 20A B5 FORCEON GND E1 VL INVALID 20A FORCEOFF C5 TO POWERMANAGEMENT UNIT VL
E2
Chip Information
TRANSISTOR COUNT: 698 PROCESS TECHNOLOGY: CMOS
______________________________________________________________________________________
11
+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
Pin Configurations
TOP VIEW
A
VCC
C2+
C2-
V-
VL
T1IN
B
V+
N.C.
N.C.
N.C.
FON
T2IN
C
C1+
N.C.
N.C.
N.C.
FOFF
R2OUT
D
C1-
N.C.
N.C.
N.C.
N.C.
R1OUT
E
GND
INV
T1OUT
T2OUT
R2IN
R1IN
1
2
3 MAX3228
4
5
6 FON = FORCEON FOFF = FORCEOFF INV = INVALID
12
______________________________________________________________________________________
+2.5V to +5.5V RS-232 Transceivers in UCSP
Pin Configurations (continued)
TOP VIEW
MAX3228/MAX3229
A
VCC
C2+
C2-
V-
VL
T1IN
B
V+
N.C.
N.C.
N.C.
FON
N.C.
C
C1+
N.C.
N.C.
N.C.
FOFF
R1OUT
D
C1-
N.C.
N.C.
N.C.
N.C.
N.C.
E
GND
INV
T1OUT
N.C.
R1IN
N.C.
1
2
3 MAX3229
4
5
6 FON = FORCEON FOFF = FORCEOFF INV = INVALID
______________________________________________________________________________________
13
+2.5V to +5.5V RS-232 Transceivers in UCSP MAX3228/MAX3229
Package Information
30L, UCSP 6x5 .EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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