TEXAS INSTRUMENTS TPS2045 TPS2055 CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES handbook
Contents
1. 005 260 C Electrostatic discharge ESD protection Human body model MIL STD 883C 2 kV Machine model 00 00 cee es 0 2 kV T 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 under recommended operating conditions is not implied Exposure to absolute maximum rated conditions for extended periods may affect device reliability NOTE 1 All voltages are with respect to GND DISSIPATION RATING TABLE Ta lt 25 C DERATING FACTOR TA 70 C Ta 85 C POWER RATING ABOVE TA 25 C POWER RATING POWER RATING PACKAGE D 725 mW 5 8 mW C 464 mW 377 mW P 1175 mW 9 4 mW C 752 mW 611 mW recommended operating conditions TPS2045 TPS2055 MN MAX MN MAX Input voltage VI IN 2 7 5 5 2 7 5 5 Continuous output current IO OUT 0 250 0 250 Operating virtual junction temperature T 40 125 40 125 di TEXAS INSTRUMENTS 4 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 electrical characteristics over recommended operating junction temperature range Vi In 5 5 V lo rated current Vi EN 0 V Vien Hi unless otherwise noted power switch TPS2045 TPS2055 PARAMETER TEST CONDITIONST Static dr2. TPS2045D f v M TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 features typical applications 135 mQ Maximum 5 V Input High Side Notebook Desktop and Palmtop PCs MOSFET Switch Monitors Keyboards Scanners and 250 mA Continuous Current Printers Short Circuit and Thermal Protection With Digital Cameras Phones and PBXs Overcurrent Logic Output Hot Insertion Applications e Operating Range 2 7 V to 5 5 V Logic Level Enable Input TPS2045 TPS2055 2 5 ms Typical Rise Time D OP VIEW E D OP VIEW E Undervoltage Lockout 104A Maximum Standby Supply Current e Bidirectional Switch Available in 8 pin SOIC and PDIP Packages Ambient Temperature Range 40 C to 85 C 2 kV Human Body Model 200 V Machine Model ESD Protection description The TPS2045 and TPS2055 power distribution switches are intended for applications where heavy capacitive loads and short circuits are likely Each of these 135 mQ N channel MOSFET high side power switches is controlled by a logic enable compatible with 5 V and 3 V logic Gate drive is provided by an internal charge pump that controls the power switch rise times and fall times to minimize current surges during switching The charge pump requires no external components and allows operation from supplies as low as 2 7 V When the output load exceeds the current limit threshold or a short is prese
3. low power bus powered functions and high power bus powered functions Both low power and high power bus powered functions obtain all power from upstream ports low power functions always draw less than 100 mA high power functions must draw less than 100 mA at power up and can draw up to 500 mA after enumeration If the load of the function is more than the parallel combination of 44 Q and 10 uF at power up the device must implement inrush current limiting see Figure 31 Power Supply D 3 3 V B TPS2045 VBUS e o GND 10nEL Internal L Function USB Control Figure 31 High Power Bus Powered Function 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 17 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 APPLICATION INFORMATION USB power distribution requirements USB can be implemented in several ways and regardless of the type of USB device being developed several power distribution features must be implemented e Bus Powered Hubs must Enable disable power to downstream ports Power up at 100 mA Limit inrush current 44 Q and 10 uF Functions must Limit inrush currents Power up at 100 mA The feature set of the TPS2045 and TPS2055 allows them to meet each of these requirements The integrated current limiting and overcurrent reporting is required by hosts and self powered hubs The logic level
4. 0 200 5 08 MAX 0 310 7 87 0 290 7 37 Seating Plane 0 125 3 18 MIN 0 100 2 54 0 021 0 53 0 015 0 38 9 0 010 0 25 V 7 M amp 0 010 0 25 NOM 4040082 B 03 95 NOTES A Alllinear dimensions are in inches millimeters B This drawing is subject to change without notice C Falls within JEDEC MS 001 35 TEXAS INSTRUMENTS 22 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 IMPORTANT NOTICE Texas Instruments and its subsidiaries TI reserve the right to make changes to their products or to discontinue any product or service without notice and advise customers to obtain the latest version of relevant information to verify before placing orders that information being relied on is current and complete All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement including those pertaining to warranty patent infringement and limitation of liability TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with Tl s standard warranty Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty Specific testing of all parameters of each device is not necessarily performed except those mandated by government
5. Figure 3 Turnoff Delay and Fall Time with 0 1 uF Load t Time ms Figure 2 Turnon Delay and Rise Time with 0 1 uF Load 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 PARAMETER MEASUREMENT INFORMATION 5 V div Vi IN 5 V TA 25C VO OUT CL 1UF 2 V div 0 1 2 3 4 5 6 7 8 9 t Time ms Figure 4 Turnon Delay and Rise Time with 1 uF Load VIN 5V Ta 25 C IO OUT 0 2 A div 1 2 3 4 5 6 7 8 9 10 t Time ms Figure 6 TPS2045 Short Circuit Current Device Enabled into Short Vi IN 5 V a safa QUE Wout teen SE aa TAz2 C CL 1 uF Ru 2200 0 2 4 6 8 10 12 14 16 18 20 t Time ms Figure 5 Turnoff Delay and Fall Time with 1 uF Load VI IN 5V Ta 25 C woo e 2 Vidiv lo OUT 0 5 A div 0 10 20 30 40 50 60 70 80 90 100 t Time ms Figure 7 TPS2045 Threshold Trip Current with Ramped Load on Enabled Device di TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 PARAMETER MEASUREMENT INFORMATION Vi IN 5V Ta 25 C RL 2200 VEN P 5 V div lo OUT p 0 2 A div 02 4 ONCE DEC NE no t Time ms Figure 8 Inrush Current with 220 uF 100 uF and 47 uF Load Capacitance Mian
6. 50 2 5 3 3 5 4 4 5 5 5 5 6 r DS on Static Drain Source On State Resistance mQ FDs on Static Drain Source On State Resistance mQ TJ Junction Temperature C Vi Input Voltage V Figure 20 Figure 21 INPUT TO OUTPUT VOLTAGE SHORT CURCUIT OUTPUT CURRENT vs vs LOAD CURRENT INPUT VOLTAGE 45 490 E TA 25 C I co 40 x 470 E e Vi IN 2 7 V m o gt e An 2 S 450 Ty 40 C 2 5 Co 30 VI IN 3 3 V o Ty 25 C 9 amp 430 E es 5 o o Ty 125 C e 20 40 o l 5 15 Vi IN 4 5 V o e 390 O 10 vi VI IN 5 V L KIN 2 370 z 5 E gt o 350 0 1 0 14 0 18 0 22 0 26 0 3 2 5 3 3 5 4 4 5 5 5 5 IL Load Current A Vi Input Voltage V Figure 22 Figure 23 di TEXAS INSTRUMENTS 12 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 Threshold Trip Current A UVLO Undervoltage Lockout V 0 73 0 71 0 69 0 67 0 65 2 5 3 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 TYPICAL CHARACTERISTICS THRESHOLD TRIP CURRENT vs INPUT VOLTAGE TA 25 C Load Ramp 1 A 10 ms 3 5 4 4 5 5 V Input Voltage V Figure 24 UNDERVOLTAGE LOCKOUT vs JUNCTION TEMPERATURE los Short circuit Output Current mA 5 5 Start Threshold Threshold Current Limit Response u s 25
7. Output Enabled A Ii IN Supply Current Output Enabled u A TYPICAL CHARACTERISTICS SUPPLY CURRENT OUTPUT ENABLED SUPPLY CURRENT OUTPUT DISABLED vs vs JUNCTION TEMPERATURE JUNCTION TEMPERATURE 200 180 160 140 120 li IN Supply Current Output Disabled nA 100 50 25 0 25 50 75 100 125 150 50 25 0 25 50 75 100 125 150 TJ Junction Temperature C Ty Junction Temperature C Figure 16 Figure 17 SUPPLY CURRENT OUTPUT ENABLED SUPPLY CURRENT OUTPUT DISABLED vs vs INPUT VOLTAGE INPUT VOLTAGE 200 2000 lt q c I o 1600 180 s G 2 a 1200 160 g Oo E 800 2 140 5 o gt 400 o 2 120 i 0 zZ 100 400 2 5 3 3 5 4 4 5 5 55 6 2 5 3 3 5 4 4 5 5 5 5 6 Vi Input Voltage V Vi Input Voltage V Figure 18 Figure 19 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 11 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 TYPICAL CHARACTERISTICS STATIC DRAIN SOURCE ON STATE RESISTANCE STATIC DRAIN SOURCE ON STATE RESISTANCE vs vs JUNCTION TEMPERATURE INPUT VOLTAGE 175 150 150 125 125 100 100 75 75 50 50 25 0 25 50 75 100 125 150
8. SLVS182 APRIL 1999 APPLICATION INFORMATION overcurrent A sense FET is employed to check for overcurrent conditions Unlike current sense resistors sense FETs do not increase the series resistance of the current path When an overcurrent condition is detected the device maintains a constant output current and reduces the output voltage accordingly Complete shutdown occurs only if the fault is present long enough to activate thermal limiting Three possible overload conditions can occur In the first condition the output has been shorted before the device is enabled or before Viy has been applied see Figure 6 The TPS2045 and TPS2055 sense the short and immediately switch into a constant current output In the second condition the short occurs while the device is enabled At the instant the short occurs very high currents may flow for a short time before the current limit circuit can react After the current limit circuit has tripped reached the overcurrent trip threshhold the device switches into constant current mode In the third condition the load has been gradually increased beyond the recommended operating current The current is permitted to rise until the current limit threshold is reached or until the thermal limit of the device is exceeded see Figure 7 The TPS2045 and TPS2055 are capable of delivering current up to the current limit threshold without damaging the device Once the threshold has been reached the device
9. requirements CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH PERSONAL INJURY OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE CRITICAL APPLICATIONS TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN LIFE SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER S RISK In order to minimize risks associated with the customer s applications adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards Tl assumes no liability for applications assistance or customer product design TI does not warrant or represent that any license either express or implied is granted under any patent right copyright mask work right or other intellectual property right of TI covering or relating to any combination machine or process in which such semiconductor products or services might be or are used Tl s publication of information regarding any third party s products or services does not constitute Tl s approval warranty or endorsement thereof Copyright O 1999 Texas Instruments Incorporated
10. switches into its constant current mode OC response The OC open drain output is asserted active low when an overcurrent or overtemperature condition is encountered The output will remain asserted until the overcurrent or overtemperature condition is removed Connecting a heavy capacitive load to an enabled device can cause momentary false overcurrent reporting from the inrush current flowing through the device charging the downstream capacitor An RC filter of 500 us see Figure 30 can be connected to the OC pin to reduce false overcurrent reporting caused by hot plug switching events or extremely high capacitive loads Using low ESR electrolytic capacitors on the output lowers the inrush current flow through the device during hot plug events by providing a low impedance energy source thereby reducing erroneous overcurrent reporting TPS2045 TPS2045 Rpullup Rpullup R filter To USB Controller T Cfilter Figure 30 Typical Circuit for OC Pin and RC Filter for Damping Inrush OC Responses 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 15 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 APPLICATION INFORMATION power dissipation and junction temperature The low on resistance on the n channel MOSFET allows small surface mount packages such as SOIC to pass large currents The thermal resistances of these packages are high compared to those of p
11. than one hub across long cables Each function must provide its own regulated 3 3 V from the 5 V input or its own internal power supply The USB specification defines the following five classes of devices each differentiated by power consumption requirements Hosis self powered hubs SPH Bus powered hubs BPH Low power bus powered functions High power bus powered functions Self powered functions Self powered and bus powered hubs distribute data and power to downstream functions The TPS2045 and TPS2055 can provide power distribution solutions for many of these classes of devices Bus powered hubs obtain all power from upstream ports and often contain an embedded function The hubs are required to power up with less than one unit load The BPH usually has one embedded function and power is always available to the controller of the hub If the embedded function and hub require more than 100 mA on power up the power to the embedded function may need to be kept off until enumeration is completed This can be accomplished by removing power or by shutting off the clock to the embedded function Power switching the embedded function is not necessary if the aggregate power draw for the function and controller is less than one unit load The total current drawn by the bus powered device is the sum of the current to the controller the embedded function and the downstream ports and it is limited to 500 mA from an upstream port
12. 0 25 50 75 100 Ty Junction Temperature C Figure 26 125 150 35 TEXAS SHORTCIRCUIT OUTPUT CURRENT vs JUNCTION TEMPERATURE 25 0 25 50 75 TJ Junction Temperature C 100 Figure 25 CURRENT LIMIT RESPONSE vs PEAK CURRENT 500 350 250 100 Peak Current A Figure 27 INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 125 13 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 TYPICAL CHARACTERISTICS OVERCURRENT 0C RESPONSE TIME vs PEAK CURRENT Overcurrent OC Time u s 0 2 4 6 8 10 Peak Current A Figure 28 APPLICATION INFORMATION TPS2045 Power Supply 2 7 V to 5 5 V Figure 29 Typical Application power supply considerations A 0 01 uF to 0 1 uF ceramic bypass capacitor between IN and GND close to the device is recommended Placing a high value electrolytic capacitor on the output pin s is recommended when the output load is heavy This precaution reduces power supply transients that may cause ringing on the input Additionally bypassing the output with a 0 01 uF to 0 1 uF ceramic capacitor improves the immunity of the device to short circuit transients di TEXAS INSTRUMENTS 14 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES
13. TA 25 M Vo oo 5 Vidiv lo OUT 77 5 V div lo OUT d n 5V 0 5 A div eC Ta 25 0 20 40 60 80 100 120 140 160 180 200 t Time ms Figure 9 Ramped Load on Enabled Device Vian 5 A 25 Vo oc 5 Vidiv lo OUT odia x 0 5 Aldiv 0 200 400 600 800 1000 0 200 400 600 800 1000 t Time us t Time us Figure 10 4 O Load Connected Figure 11 1 O Load Connected to Enabled Device to Enabled Device iz TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 TYPICAL CHARACTERISTICS TURNON DELAY TURNOFF DELAY vs vs INPUT VOLTAGE INPUT VOLTAGE I E 5 E E 2 5 3 3 5 4 4 5 5 5 5 6 2 5 3 3 5 4 4 5 5 5 5 6 Vj Input Voltage V Vi Input Voltage V Figure 12 Figure 13 RISE TIME FALL TIME vs vs LOAD CURRENT LOAD CURRENT E E E i E o 2 T rs u l l 0 0 05 01 0 15 0 2 025 0 3 0 35 04 0 0 05 01 0 15 0 2 0 25 03 0 35 0 4 IL Load Current A IL Load Current A Figure 14 Figure 15 35 TEXAS INSTRUMENTS 10 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 l IN Supply Current
14. V Vi EN Hi unless otherwise noted continued supply current TPS2045 TPS2055 PARAMETER TEST CONDITIONS UNIT TYP MAX MIN TYP MAX Supply ieee TPS2045 current No Load VEN VIN 40 6 lt Ty lt 125 C low level on OUT Ty 25 C TPS2055 output VEN 40 C lt TJ lt 125 C 25 C 10 1 10 TJ225 100 Supply VIEN 0 V TPS2045 current No Load 40 C lt Ty lt 125 C 100 high level on OUT E 25 C E S0 100 TPS2055 0 015 Leakage QUT VIEN ViiN 40 C lt Ty lt 125 C TPS2045 a M t connected undervoltage lockout TPS2045 TPS2055 PARAMETER TEST CONDITIONS UNIT overcurrent OC TPS2045 TPS2055 PARAMETER TEST CONDITIONS UNIT TET Output low voltage lo 5V VOoL OC E t Specified by design not production tested D spa ee v O ce 35 TEXAS INSTRUMENTS 6 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 PARAMETER MEASUREMENT INFORMATION OUT RL CL Vo our B 3 10 10 TEST CIRCUIT VK N 50 5096 VI EN 50 50 lon 74 gt lt toff ton 74 toff Vo OUT 90 VO OUT 90 1096 10 VOLTAGE WAVEFORMS Figure 1 Test Circuit and Voltage Waveforms VEN pa Vi EN 5 V div 5 V div ViN 5V Vian v De Ta 250 O OUT TA 25 Vo ouT 2 V div 2 Vidiv ea e ae i 0 1000 2000 3000 4000 5000 t Time ms
15. a hot plugging mechanism for any device di TEXAS INSTRUMENTS 20 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 D R PDSO G 14 PIN SHOWN 0 050 1 27 0 020 0 51 0 014 0 35 8 MECHANICAL DATA PLASTIC SMALL OUTLINE PACKAGE 0 010 0 25 V A 0 008 0 20 NOM 0 244 6 20 0 228 5 80 0 157 4 00 0 150 3 81 n Taras Plane 4 sy 0 010 0 25 7 x 0 044 1 12 0 016 0 40 E HHHHAHB l am Sh 069 1 75 MAX NOTES A DOM 0 010 0 a 0 004 0 10 0 004 0 10 DIM PINS A MAX A MIN 4040047 D 10 96 All linear dimensions are in inches millimeters This drawing is subject to change without notice Body dimensions do not include mold flash or protrusion not to exceed 0 006 0 15 Falls within JEDEC MS 012 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 21 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 MECHANICAL DATA P R PDIP T8 PLASTIC DUAL IN LINE PACKAGE 0 400 10 60 D 0 355 9 02 aa 0 260 6 60 0 240 10 ul 0 070 1 78 MAX 0 020 0 51 MIN EN
16. ain source on state TJ 85 C resistance 5 V operation i IN 5 V Ty 125 C lo 0 25 A Static drain source on state N 3 3V Ty 85 C resistance 3 3 V operation lo 0 25 A ViIN 9 3 V Ty 125 lo 0 25 A VI IN 5 5 V Ty 25 C C 1 uF RL 20 O VI IN 2 7 V Ty 2 25 C C 1 pF RL 22090 VI IN 5 5 V Tj 25 C CL 1 pF RL 20 2 ViIN 2 7 V Ty 25 C C 1 uF RL 2200 t Pulse testing techniques maintain junction temperature close to ambient temperature thermal effects must be taken into account separately Rise time output Fall time output enable input EN or EN TPS2045 TPS2055 PARAMETER TEST CONDITIONS UNIT MIN TYP MAX MIN TYP MAX EEE E CENE SCENE V ES SE ENTER RETE m S mE y lot Tumf m JoL f00uE R 2a o mm current limit PARAMETER TEST CONDITIONST Ipse nucis MIN TYP MIN TYP 5 V OUT connected to GND Short circuit output current MULA enabled into short circuit 0 345 0 44 0 525 0 345 0 44 0 525 T Pulse testing techniques maintain junction temperature close to ambient temperature thermal effects must be taken into account separately 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 5 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 electrical characteristics over recommended operating junction temperature range V jn 5 5 V lo rated current VIEN 0
17. ated on the page s l specifying its electrical characteristics TEXAS Copyright 1999 Texas Instruments Incorporated INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 1 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 TPS2045 functional block diagram Power Switch IN e OUT Current n Limit m oc A Thermal m GND Sense Ez tCurrent Sense Terminal Functions TERMINAL ODE 0 Tug ESB DORP Enable input Logic low turns on power switch Enable input Logic high turns on power switch Ground Input voltage Over current Logic output active low Power switch output di TEXAS INSTRUMENTS 2 POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 detailed description power switch The power switch is an N channel MOSFET with a maximum on state resistance of 135 mQ Vi In 5 V Configured as a high side switch the power switch prevents current flow from OUT to IN and IN to OUT when disabled The power switch can supply a minimum of 250 mA per switch charge pump An internal charge pump supplies power to the driver circuit and provides the necessary voltage to pull the gate of the MOSFET above the source The charge pump operates from input voltages as low as 2 7 V and requires very little supply current driver The d
18. enable and controlled rise times meet the need of both input and output ports on bus power hubs as well as the input ports for bus power functions see Figure 32 di TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 APPLICATION INFORMATION TUSB2040 Hub Controller SN75240 Upstream AC dip ee Port B D orts e D Ferrite Beads AC errite Beads aw B D SN75240 e 5V hg S 3urt e Ac D B D D Ferrite Beads SN75240 GND DM4 e E e 5V TPS2045 PWRON1 EN E 33 urt OVRCUR1 oc Em ae Ferrite Beads Crystal as Tuning Circuit d f T 33urt OCSOFF E 0 1 pF D GND Hd Ferrite Beads GND L ml 5V T 33 urt t USB rev 1 1 requires 120 uF per hub Figure 32 Bus Powered Hub Implementation 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 19 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 APPLICATION INFORMATION generic hot plug applications see Figure 33 In many applications it may be necessary to remove modules or pc boards while the main unit i
19. he switch continues to cycle in this manner until the load fault or input power is removed undervoltage lockout UVLO Anundervoltage lockout ensures that the power switch is in the off state at power up Wheneverthe input voltage falls below approximately 2 V the power switch will be quickly turned off This facilitates the design of hot insertion systems where it is not possible to turn off the power switch before input power is removed The UVLO will also keep the switch from being turned on until the power supply has reached at least 2 V even if the switch is enabled Upon reinsertion the power switch will be turned on with a controlled rise time to reduce EMI and voltage overshoots diz TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 APPLICATION INFORMATION Universal Serial Bus USB applications The Universal Serial Bus USB interface is a 12 Mb s or 1 5 Mb s multiplexed serial bus designed for low to medium bandwidth PC peripherals e g keyboards printers scanners and mice The four wire USB interface is conceived for dynamic attach detach hot plug unplug of peripherals Two lines are provided for differential data and two lines are provided for 5 V power distribution USB data is a 3 3 V level signal but power is distributed at 5 V to allow for voltage drops in cases where power is distributed through more
20. nt the TPS2045 and TPS2055 limit the output current to a safe level by switching into a constant current mode pulling the overcurrent OC logic output low When continuous heavy overloads and short circuits increase the power dissipation in the switch causing the junction temperature to rise a thermal protection circuit shuts off the switch in overcurrentto prevent damage Recovery from a thermal shutdown is automatic once the device has cooled sufficiently Internal circuitry ensures the switch remains off until valid input voltage is present The TPS2045 and TPS2055 are designed to limit at 0 44 A load These power distribution switches available in 8 pin small outline integrated circuit SOIC and 8 pin plastic dual in line packages PDIP operate over an ambient temperature range of 40 C to 85 C AVAILABLE OPTIONS RECOMMENDED TYPICAL SHORT cIRCUIT PACKAGED DEVICES T ENABLE MAXIMUM CONTINUOUS GURRENT LIMIT AT 25 C A LOAD CURRENT K SOIC PDIP A A D t P ACeS TPS20450 _ TPS2045P t The D package is available taped and reeled Add an R suffix to device type e g TPS2045DR Please be aware that an important notice concerning availability standard warranty and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet This document contains information on products in more than one phase of development The status of each device is indic
21. on the load thermal sense An internal thermal sense circuit shuts off the power switch when the junction temperature rises to approximately 140 C Hysteresis is built into the thermal sense circuit After the device has cooled approximately 20 C the switch turns back on The switch continues to cycle off and on until the fault is removed undervoltage lockout A voltage sense circuit monitors the input voltage When the input voltage is below approximately 2 V a control signal turns off the power switch 35 TEXAS INSTRUMENTS POST OFFICE BOX 655303 9 DALLAS TEXAS 75265 3 TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES SLVS182 APRIL 1999 absolute maximum ratings over operating free air temperature range unless otherwise noted t Input voltage range Viy see Note 1 iisi iss css si e 0 3 V to 6 V Output voltage range Vo ouT see Note 1 0 ee eee eee 0 3 V to Vi in 0 3 V Input voltage range VEN OF VIEN eek emet eh paira REX nodes RR er dnd 0 3 V to 6 V Continuous output current lotgUT se nnn internally limited Continuous total power dissipation 0 0c cece eee eee ees See Dissipation Rating Table Operating virtual junction temperature range TJ cece eee tte e eee 40 C to 125 C Storage temperature range Tete xus ce hv Ra e pa dad Da ia Oei e pa 65 C to 150 C Lead temperature soldering 1 6 mm 1 16 inch from case for 10 seconds
22. ower packages it is good design practice to check power dissipation and junction temperature The first step is to find rps on at the input voltage and operating temperature As an initial estimate use the highest operating ambient temperature of interest and read rDS on from Figure 21 Next calculate the power dissipation using P x 2 D DS on Finally calculate the junction temperature Tj P T Where D X Foun TA Ambient Temperature C Roya Thermal resistance SOIC 172 C W PDIP 106 C W Compare the calculated junction temperature with the initial estimate If they do not agree within a few degrees repeat the calculation using the calculated value as the new estimate Two or three iterations are generally sufficient to get a reasonable answer thermal protection Thermal protection prevents damage to the IC when heavy overload or short circuit faults are present for extended periods of time The faults force the TPS2045 and TPS2055 into constant current mode which causes the voltage across the high side switch to increase under short circuit conditions the voltage across the switch is equal to the input voltage The increased dissipation causes the junction temperature to rise to high levels The protection circuit senses the junction temperature of the switch and shuts it off Hysteresis is built into the thermal sense circuit and after the device has cooled approximately 20 degrees the switch turns back on T
23. river controls the gate voltage of the power switch To limit large current surges and reduce the associated electromagnetic interference EMI produced the driver incorporates circuitry that controls the rise times and fall times of the output voltage The rise and fall times are typically in the 2 ms to 4 ms range enable EN or EN Thelogic enable disables the power switch and the bias for the charge pump driver and other circuitry to reduce the supply current to less than 10 uA when a logic high is present on EN TPS2045 or a logic low is present on EN TPS2055 A logic zero input on EN or a logic high on EN restores bias to the drive and control circuits and turns the power on The enable input is compatible with both TTL and CMOS logic levels overcurrent OC The OC open drain output is asserted active low when an overcurrent or overtemperature condition is encountered The output will remain asserted until the overcurrent or overtemperature condition is removed current sense A sense FET monitors the current supplied to the load The sense FET measures current more efficiently than conventional resistance methods When an overload or short circuit is encountered the current sense circuitry sends a control signal to the driver The driver in turn reduces the gate voltage and drives the power FET into its saturation region which switches the output into a constant current mode and holds the current constant while varying the voltage
24. s still operating These are considered hot plug applications Such implementations require the control of current surges seen by the main power supply and the card being inserted The most effective way to control these surges is to limit and slowly ramp the current and voltage being applied to the card similar to the way in which a power supply normally turns on Due to the controlled rise times and fall times of the TPS2045 and TPS2055 these devices can be used to provide a softer start up to devices being hot plugged into a powered system The UVLO feature ofthe TPS2045 and TPS2055 also ensures the switch will be off after the card has been removed and the switch will be off during the next insertion The UVLO feature guarantees a soft start with a controlled rise time for every insertion of the card or module p I4 PC Board Power TPS2045 Block of Supply OUT Circuitry 2 7 V to 5 5 V e _ 1000 uF EL T Optimum S A Djs ale Overcurrent Response L Figure 33 Typical Hot Plug Implementation By placing the TPS2045 and TPS2055 between the Vcc input and the rest of the circuitry the input power will reach these devices first after insertion The typical rise time of the switch is approximately 2 5 ms providng aslow voltage ramp atthe output of the device This implementaion controls system surge currents and provides
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TEXAS INSTRUMENTS TPS2045 TPS2055 CURRENT LIMITED POWER DISTRIBUTION SWITCHES handbook