UC3907DW


 
        SLUS165C – MARCH 1999 - REVISED JANUARY 2002 FEATURES D Fully Differential High Impedance Voltage Sensing SOIC-16 DW PACKAGE (TOP VIEW) C/S OUT C/S (+) C/S (–) (–) SENSE POWER RETURN ARTIFICIAL GND VREF ISET D Accurate Current Amplifier for Precise C/S (–) 2 1 CURRENT SHARE BUS N/C 3 STATUS INDICATE C/S OUT PLCC-20, LCC-20, Q OR L PACKAGE (TOP VIEW) C/S (+) D D D D Current Sharing Opto Coupler Driving Capability 1.25% Trimmed Reference Master Status Indication 4.5-V to 35-V Operation 20 19 18 ADJ OUT (–) SENSE 5 17 ADJ INPUT N/C 6 16 POWER RETURN 7 15 8 14 VCC N/C OPTO DRIVE DESCRIPTION ISET VREF 9 10 11 12 13 16 15 14 13 12 11 10 9 STATUS INDICATE CURRENT SHARE BUS ADJ OUT ADJ INPUT COMP (+) SENSE VCC OPTO DRIVE DIL-16 J or N PACKAGE (TOP VIEW) 4 ARTIFICIAL GND 1 2 3 4 5 6 7 8 N/C COMP (+) SENSE C/S OUT C/S (+) C/S (–) (–) SENSE POWER RETURN ARTIFICIAL GND VREF ISET 1 16 2 15 3 14 4 13 5 12 6 11 7 10 8 9 STATUS INDICATE CURRENT SHARE BUS ADJ OUT ADJ INPUT COMP (+) SENSE VCC OPTO DRIVE The UCx907 family of load share controller ICs provides all the necessary features to allow multiple-independent-power modules to be paralleled such that each module supplies only its proportionate share to total-load current. This sharing is accomplished by controlling each module’s power stage with a command generated from a voltage-feedback amplifier whose reference can be independently adjusted in response to a common-share-bus voltage. By monitoring the current from each module, the current share bus circuitry determines which paralleled module would normally have the highest output current and, with the designation of this unit as the master, adjusts all the other modules to increase their output current to within 2.5% of that of the master. The current share bus signal interconnecting all the paralleled modules is a low-impedance, noise-insensitive line which will not interfere with allowing each module to act independently should the bus become open or shorted to ground. The UC3907 controller will reside on the output side of each power module and its overall function is to supply a voltage feedback loop. The specific architecture of the power stage is unimportant. Either switching or linear designs may be utilized and the control signal may be either directly coupled or isolated though the use of an optocoupler or other isolated medium. Other features of the UC3907 include 1.25% accurate reference: a low-loss, fixed-gain current-sense amplifier, a fully differential, high-impedance voltage sensing capability, and a status indicator to designate which module is performing as master. 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. Copyright  2000, Texas Instruments Incorporated 
     !"#   $"%&! '#( '"! !  $#!! $# )# #  #*  "# '' +,( '"! $!# - '#  #!# &, !&"'# # -  && $## ( www.ti.com 1 

 
        SLUS165C – MARCH 1999 - REVISED JANUARY 2002 block diagram VOLTAGE ERROR AMPLIFIER (+) SENSE 11 + 12 V CC 1.75 V 0.25 V GROUND AMPLIFIER (–) SENSE 4 POWER RTN 5 9 OPTO DRIVE V REF 1.75 V – GND + 8 ISET + DRV – 1 kΩ 20 k Ω 50 kΩ ADJUST AMPLIFIER 6 14 ADJ OUT 13 ADJ INPUT 15 CURRENT SHARE BUS 16 STATUS INDICATE 50 mV + ARTIFICIAL GND DRIVE 1.0 V AMPLIFIER COMP + + VCC (4.5 V TO 35 V) 10 – VREF 7 C/S OUT 1 17.5 kΩ – ADJ + 40 kΩ 2 kΩ C/S (–) 3 – 2 kΩ C/S (+) BUFFER AMPLIFIER CURRENT SENSE AMPLIFIER 100 – + + 2 10 k Ω 40 k Ω absolute maximum ratings over operating free-air temperature (unless otherwise noted)† Supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V Opto out voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V Opto out current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA Status indicate sink current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA C/S input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V Share bus voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 35 V Other analog inputs and outputs (zener clamped) maximum forced voltage . . . . . . . . . . . . . . . . –0.3 V to10 V Other analog inputs and outputs (zener clamped) maximum forced current . . . . . . . . . . . . . . . . . . . . . ±10 mA Ground amp sink current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mA Pins 1, 9, 12, 15 sink current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C Junction temperature, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to 150°C Lead temperature (solder 10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300°C † Pin Nos. refer to 16 Pin DIL Package. ‡ Currents are positive into, negative out of the specified terminal. Consult packaging section of databook for thermal limitations and considerations of package. 2 www.ti.com 

 
        SLUS165C – MARCH 1999 - REVISED JANUARY 2002 electrical characteristics, these specifications apply for TA = –55°C to 125°C for UC1907, –40°C to 85°C for UC2907, and 0°C to 70°C for UC3907, VIN = 15 V, TA = TJ (unless otherwise stated ) PARAMETER TEST CONDITIONS MIN TYP MAX UNITS 1.975 2.000 2.025 V 1.960 2.000 2.040 Voltage Amp Section COMP = 1 V, Inp t voltage Input oltage Line regulation Load regulation Long term stability TA = 25°C over temp COMP = 1 V, VIN = 4.5 V to 35 V IL reference = 0.0 mA to –10 mA Total output variation TA = 125°C, Line, load, temp 1000hrs See Note 2 Input adjust range ADJ OUT from max high to max low 5 1.960 Input bias current 85 V 15 mV 10 mV 25 mV 2.040 100 115 mV µA –1 Open loop gain COMP = 0.75 V to 1.5 V Unity gain bandwidth See Note 2 Output sink current TA = 25°C (+) SENSE = 2.2 V, COMP = 1 V 6 15 mA Output source current (+) SENSE = 1.8 V, COMP = 1 V 400 600 µA VOUT high VOUT low (+) SENSE = 1.8 V, IL = –400 µΑ IL = 1 mA 1.85 2 V (+) SENSE = 2.2 V, 65 dB 700 kHz 0.15 0.40 V 1.970 2.000 2.030 V 1.955 2.000 2.045 –15 –30 –60 mA 200 250 300 mV 5 mV 10 mV 15 mV 60 mV Reference Section O tp t voltage Output oltage TA = 25°C Over operating temp Short circuit current VREF = 0.0 V V Ground Amp Section Output voltage Common mode variation (–) SENSE from 0.0 V to 2 V Load regulation reg lation IL = 0.0 mA to 20 mA, IL = 0.0 mA to 20 mA, TA = 25°C over temp Adjust Amp Section Input offset voltage ADJ OUT = 1.5 V, VCM = 0.0 V Input bias current 40 50 µA –2 Open loop gain 1.5 V ≤ ADJ OUT ≤ 2.25 V Unity gain bandwidth TA = 25°C, COUT =1 µF See Note 2 IOUT = –10 µA to 10 µA, VOUT = 1.5 V 1.7 3 4.5 ms VID = 0.0 V, VID = 250 mV, ADJ OUT = 1.5 V 55 135 225 µA Output source current ADJ OUT = 1.5 V 110 200 350 µA VOUT high VOUT low VID = 250 mV, VID = 0.0 V, IOUT = – 50 mA IOUT = 50 mA 2.20 2.70 2.90 V 0.75 1.15 Common mode rejection ratio VCM = 0.0 to 10 V VOUT ADJ OUT = 1.5 V to 2 V, ∆(+) SENSE/ ∆ADJ OUT Transconductance Output sink current Output gain to V/A 65 dB 500 Hz 70 50 V dB 57 64 mV/V NOTE 1: Unless otherwise specified all voltages are with respect to (–) SENSE. Currents are positive into, negative out of the specified terminal. NOTE 2: Ensured by design. Not production tested. www.ti.com 3 

 
        SLUS165C – MARCH 1999 - REVISED JANUARY 2002 electrical characteristics, these specifications apply for TA = –55°C to 125°C for UC1907, –40°C to 85°C for UC2907, and 0°C to 70°C for UC3907, VIN = 15 V, TA = TJ (unless otherwise stated ) PARAMETER TEST CONDITIONS MIN TYP MAX UNITS 19.2 19.6 20.1 V/V 210 250 290 mV 180 250 330 mV 600 µV/V 450 mV Current Amp Section Gain O tp t voltage Output oltage Input offset change with common mode input VCM = 0.0 V, VC/S (+) = VC/S (–) = 0.0 V, VC/S (+) = VC/S (–) = 0.0 V, VCM = 0 V to 13 V VOUT high VOUT low VID = 1 V VID = – 1 V, Power supply rejection ratio VIN = 4.5 V to 35 V, VID = 50 mV to 100 mV TA = 25°C over temp 10 IL = 1 mA VCM = 0.0 V 14.5 350 V 60 Slew rate dB 0.4 V/µs Drive Amp Section RSET = 500 Ω to Artificial GND, Opto Drive = 15 V Voltage gain COMP = 0.5 V to 1 V 2.3 2.5 2.6 ISET VOUT high ISET VOUT low (+) SENSE = 2.2 V 3.8 4.1 4.4 V 270 300 mV 35 V 1.55 1.65 1.75 V 5 mV 5 10 20 kΩ 6 15 (+) SENSE = 1.8 V Opto out voltage range 4 Zero current input threshold V/V Buffer Amp Section Input offset voltage Input = 1 V Output off impedance Input = 1 V, output = 1.5 V to 2 V Output source current Input = 1 V, output = 0.5 V Common mode rejection ratio VCM = 0.3 V to 10 V VIN = 4.5 V to 35 V Power supply rejection ratio mA 70 dB 70 dB Under Voltage Lockout Section Startup threshold 3.7 Threshold hysteresis 200 4.4 V mV Status Indicate Section VOUT low Output leakage ADJ OUT = current share bus ADJ OUT = 1 V, VOUT = 35 V 0.2 0.5 V 0.1 5 µA 3 5 mA 6 10 mA Total Stand by Current Section Startup current Operating current VIN = UVLO – 0.2 V VIN = 35 V NOTE 1: Unless otherwise specified all voltages are with respect to (–) SENSE. Currents are positive into, negative out of the specified terminal. NOTE 2: Ensured by design. Not production tested. 4 www.ti.com 

 
        SLUS165C – MARCH 1999 - REVISED JANUARY 2002 pin assignments (–) SENSE: (Pin 4) This is a high-impedance pin allowing remote sensing of the system ground, bypassing any voltage drops which might appear in the power return line. This point should be considered as the true ground. Unless otherwise stated, all voltages are with respect to this point. Artificial Ground: (Pin 6) This is a low-impedance-circuit ground which is exactly 250 mV above the (–) SENSE terminal. This offset allows the ground buffer amplifier negative headroom to return all the control bias and operating currents while maintaining a high impedance at the (–) SENSE input. Power RTN: (Pin 5) This should be the most negative voltage available and can range from zero to 5 V below the (–) SENSE terminal. It should be connected as close to the power source as possible so that voltage drops across the return line and current-sensing impedances lie between this terminal and the (–) SENSE point. VREF: (Pin 7) The internal voltage reference is a band-gap circuit set at 2.0 V with respect to the (–) SENSE input (1.75 V above the artificial ground), and an accuracy of ±1.5%. This circuit, as well as all the other chip functions, will work over a supply voltage range of 4.5 V to 35 V allowing operation from unregulated dc, an auxiliary voltage, or the same output voltage that it is controlling. Under-voltage lockout has been included to insure proper startup by disabling internal bias currents until the reference rises into regulation. Voltage Amplifier: (Pins 11, 12) This circuit is the feedback-control-gain stage for the power module’s output-voltage regulation, and overall-loop compensation will normally be applied around this amplifier. Its output will swing from slightly above the ground return to an internal clamp of 2.0 V. The reference trimming is performed closed loop, and measured at pin 11, (+) SENSE. The value is trimmed to 2 V ±1.25%. Drive Amplifier: (Pins 8, 9, 12) This amplifier is used as an inverting buffer between the voltage amplifier’s output and the medium used to couple the feedback signal to the power controller. It has a fixed-voltage gain of 2.5 and is usually configured with a current-setting resistor to ground. This establishes a current-sinking output optimized to drive optical couplers biased at any voltage from 4.5 V to 35 V, with current levels up to 20 mA. The polarity of this stage is such that an increasing voltage at the voltage amplifier’s sense input (as, for example, at turnon) will increase the opto’s current. In a nonisolated application, a voltage signal ranging from 0.25 V to 4.1 V may be taken from the current-setting output but it should be noted that this voltage will also increase with increasing sense voltage and an external inverter may be required to obtain the correct feedback polarity. Current Amplifier: (Pins 1, 2, 3) This amplifier has differential-sensing capability for use with an external shunt in the power-return line. The common mode range of its input will accommodate the full range between the power return point and VCC-2 V which will allow undefined-line impedances on either side of the current shunt. The gain is internally set at 20, giving the user the ability to establish the maximum-voltage drop across the current-sense resistor at any value between 50 mV and 500 mV. While the bandwidth of this amplifier may be reduced with the addition of an external-output capacitor to ground, in most cases this is not required as the compensation of the adjust amplifier will typically form the dominant pole in the adjust loop. Buffer Amplifier: (Pins 1, 15) This amplifier is a unidirectional buffer which drives the current-share bus. The line which will interconnect all power modules paralleled for current sharing. Since the buffer amplifier will only source current, it insures that the module with the highest-output current will be the master and drive the bus with a low-impedance drive capability. All other buffer amplifiers will be inactive with each exhibiting a 10-kΩ load impedance to ground. The share bus terminal is protected against both shorts to ground and accidental voltages in excess of 50 V. www.ti.com 5 

 
        SLUS165C – MARCH 1999 - REVISED JANUARY 2002 pin assignments Adjust Amplifier: (Pins 13, 14, 15) This amplifier adjusts the individual module’s reference voltage to maintain equal-current sharing. It is a transconductance type in order that its bandwidth may be limited and noise kept out of the reference-adjust circuitry, with a simple capacitor to ground. The function of this amplifier is to compare its own module-output current to the share-bus signal, which represents the highest output current. This will force an adjust command which is capable of increasing the reference voltage as seen by the voltage amplifier by as much as 100 mV. This number stems from the 17.5:1 internal resistor ratio between the adjust amplifier’s clamped output and the reference, and represents a 5% total range of adjustment. This value should be adequate to compensate for unit-to-unit reference and external-resistor tolerances. The adjust amplifier has a built-in 50-mV offset on its inverting input which will force the unit acting as the master to have a low output, resulting in no change to the reference. While this 50-mV offset represents an error in current sharing, the gain of the current amplifier reduces it to only 2.5 mV across the current-sense resistor. It should also be noted that when the module is acting independently with no connection to the share bus node, or when the share bus node is shorted to ground, its reference voltage will be unchanged. Since only the circuit acting as a master will have a low output from the adjust amplifier, this signal is used to activate a flag output to identify the master, should some corrective action be needed. Status Indicate: (Pin 16) This pin is an open-collector output intended to indicate the unit which is acting as the master. It achieves this by sensing when the adjust amp is in its low state and pulling the status-indicate pin low. additional information Please refer to additional application information. 1. By Mark Jordan, UC3907 Load Share IC Simplifies Parallel Power Supply Design, TI Literature Number SLUA147. 2. By Laszlo Balogh, UC3902 Load Share Controller and its Performance in Distributed Power Systems, TI Literature Number SLUA128. UDG-94103 Figure 1. Load System Diagram 6 www.ti.com 

 
        SLUS165C – MARCH 1999 - REVISED JANUARY 2002 additional information (continued) V CC 0–20 mA ISOLATED CONTROL UC3907 12 + 1.0 V VOLTAGE ERROR AMPLIFIER (+) SENSE 11 V REFRANGE 2.0 V–2.1 V – 20 k Ω – DRIVE AMPLIFIER + 9 ISET 50 k Ω 0–4 V DIRECT CONTROL 8 + REF MASTER INDICATE 1.75 V 7 V CC 16 V CC 1.750 V REF 10 + 0.250 V ADJUST AMPLIFIER + GND AMPLIFIER – 50 mV + – ( ) SENSE 4 + 20X – + BUFFER AMPLIFIER – + CURRENT SHARE BUS 15 10 k Ω ARTIFICIAL GND 6 2 FROM LOAD 3 14 CURRENT SENSE + 1 ADJ COMP 13 C/S OUT 5 ADJ IN PWR RET TO PWR RETURN MODULE LOAD CURRENT UDG-99053 Figure 2. Load System Connection Diagram UDG-94105 Figure 3. UC3907 In a Load-Sharing Feedback Loop for an Off-Line Isolated Supply www.ti.com 7 PACKAGE OPTION ADDENDUM www.ti.com 14-Oct-2022 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) UC2907DW ACTIVE SOIC DW 16 40 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 UC2907DW Samples UC2907DWG4 ACTIVE SOIC DW 16 40 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 UC2907DW Samples UC2907DWTR ACTIVE SOIC DW 16 2000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 UC2907DW Samples UC2907N ACTIVE PDIP N 16 25 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 UC2907N Samples UC2907NG4 ACTIVE PDIP N 16 25 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 UC2907N Samples UC3907DW ACTIVE SOIC DW 16 40 RoHS & Green NIPDAU Level-2-260C-1 YEAR 0 to 70 UC3907DW Samples UC3907DWTR ACTIVE SOIC DW 16 2000 RoHS & Green NIPDAU Level-2-260C-1 YEAR 0 to 70 UC3907DW Samples UC3907N ACTIVE PDIP N 16 25 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 UC3907N Samples UC3907NG4 ACTIVE PDIP N 16 25 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 UC3907N Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of