UC3178 Full Bridge Power Amplifier FEATURES DESCRIPTION • Precision Current Control • ±450mA Load Current • 1.2V Typical Total Vsat at 450mA • Programmable Over-Current Control • Range Control for 4:1 Gain Change The UC3178 full-bridge power amplifier, rated for continuous output current of 0.45 Amperes, is intended for use in demanding servo applications. This device includes a precision current sense amplifier that senses load current with a single resistor in series with the load. The UC3178 is optimized to consume a minimum of supply current, and is designed to operate in both 5V and 12V systems. The power output stages have a low saturation voltage and are protected with current limiting and thermal shutdown. When inhibited, the device will draw less than 1.5mA of total supply current. • Compensation Adjust Pin for Range Bandwidth Control • Inhibit Input and UVLO • 3V to 15V Operation • 12mA Quiescent Supply Current Auxiliary functions on this device include a load current sensing and rectification function that can be configured with the device’s over-current comparator to provide tight control on the maximum commanded load current. The closed loop transconductance of the configured power amplifier can be switched between a high and low range with a single logic input. The 4:1 change in gain can be used to extend the dynamic range of the servo loop. Bandwidth variations that would otherwise result with the gain change can be controlled with a compensation adjust pin. This device is packaged a power PLCC, "QP" package which maintains a standard 28-pin outline, but with 7 pins along one edge directly tied to the die substrate for improved thermal performance. BLOCK DIAGRAM UDG-92010 5/93 UC3178 ABSOLUTE MAXIMUM RATINGS CONNECTION DIAGRAM Input Supply Voltage, (VIN(+), VC(+)) . . . . . . . . . . . . . . . . . . 20V O/C Sense, Logic Inputs, and REF Input Maximum forced voltage . . . . . . . . . . . . . . . . . -0.3V to 10V Maximum forced current . . . . . . . . . . . . . . . . . . . . . . ±10mA A & B Amplifier Inputs . . . . . . . . . . . . . -0.3V to (VIN(+) + 1.0V) O/C Indicate Open Collector Output Voltage . . . . . . . . . . . . 20V A and B Output Currents(continuous) Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internally Limited Sink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6A Output Diode Current (pulsed)* . . . . . . . . . . . . . . . . . . . . . 0.5A O/C Ind Output Current(continuous) . . . . . . . . . . . . . . . . 20mA Operating Junction Temperature . . . . . . . . . . . . . . . . . . +150°C Storage Temperature . . . . . . . . . . . . . . . . . . . -65°C to +150°C PLCC - 28 (Top View) QP Package *Notes: Unless otherwise indicated, voltages are referenced to ground and currents are positive into, negative out of, the specified terminals, "Pulsed" is defined as a less than 10% duty cycle pulse with a maximum duration of 500µs. THERMAL DATA QP package: (see packaging section of UICC data book for more details on thermal performance) Thermal Resistance Junction to Leads, θjl . . . . . . . . 15°C/W Thermal Resistance Junction to Ambient, θja . . . 30-40°C/W Note: The above numbers for θjl are maximums for the limiting thermal resistance of the package in a standard mounting configuration. The θja numbers are meant to be guidelines for the thermal performance of the device/pc-board system. All of the above numbers assume no ambient airflow. PACKAGE PIN FUNCTION FUNCTION PIN Inhibit O/C Force O/C Sense Range C/S(+) Comp Adj O/C Ind AIN(+) AIN(-) VC(+) Supply A Output Pwr Gnd Pwr Gnd Pwr Gnd Pwr Gnd Pwr Gnd Pwr Gnd Pwr Gnd B Output VIN(+) BIN(-) BIN(+) REF Input C/S(+) C/S Out IDIF Out IDIF REF Ground 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 ELECTRICAL CHARACTERISTICS: Unless otherwise stated specifications hold for TA = 0°C to 70°C, VC(+) = VIN(+) = 12V, REF Input = VIN(+)/2, O/C Input & Inhibit Input = 0V. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS IOUT = OA 12 1.2 16 2.0 mA mA Supplies = 5V,IOUT = OA 12 16 mA Supplies = 12V,IOUT = OA 13 18 mA 2.6 2.8 Input Supply VIN (+)Supply Current VC(+) Supply Current Total Supply Current VIN(+) UVLO Threshold low to high UVLO Threshold Hysterisis V 300 mV -.01 µA Over-Current (O/C) Comparator Input Bias Current V input = 0.8V -1.0 Thresholds low to high 0.97 1.0 1.03 V 85 100 115 mV 0.2 0.45 V 5.0 µA A Amplifier, VCM = 6V 4.0 mV B Amplifier, VCM = 6V 12.0 mV Threshold Hysterisis O/C IND Vsat IOUT = 5mA, V input low O/C IND Leakage VOUT = 20V Power Amplifiers A and B Input Offset Voltage Input Bias Current VCM = 6V -500 -50 µΑ CMRR VCM = 0.5 to 13V, Supplies = 15V 70 90 dB PSRR VIN(+) = 4 to 15V, VCM = 1.5V 70 90 dB Large Signal Voltage Gain Supplies = 12V, VOUT = 1V, IOUT = 300mA 3.0 15.0 V/mV to VOUT = 10.5V, IOUT = -300mA 2 UC3178 Unless otherwise stated specifications hold for TA = 0°C to 70°C , VC(+) = VIN(+) = 12V, ELECTRICAL CHARACTERISTICS (cont.): REF Input = VIN(+)/2, O/C Input & Inhibit Input = 0V. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Power Amplifiers A & B (cont.) Gain Bandwith Product A Amplifier 2.0 MHz B Amplifier 1.0 MHz Slew Rate High-Side Current Limit Output Saturation Voltage High-Side Diode, Vf 0.45 1.0 V/µs 0.65 A High-Side, IOUT = -100mA 0.75 V High-Side, IOUT = -300mA 0.85 V High-Side, IOUT = -450mA 0.9 V Low-Side, IOUT = 100mA 0.2 V Low-Side, IOUT = 300mA 0.25 V Low-Side, IOUT = 450mA 0.30 V Total Vsat, IOUT = 100mA 0.95 1.2 V Total Vsat, IOUT = 300mA 1.05 1.4 V Total Vsat, IOUT = 450mA 1.25 1.6 ID = 450mA 1.30 V V Current Sense Amplifier Input Offset Voltage VCM = 6V, Low range mode 2.0 mV High range mode 4.0 mV Input Offset Change VCM = -1V to 13V, Supplies = 12V, Low Range Mode 2000 µV/V with Common Mode Input VCM = -1V to 13V, Supplies = 12V, High Range Mode 4000 µV/V Voltage Gain VDIFF = +1.0 to -1.0V, Vcm = 6V, High Range Mode 0.485 0.50 0.515 V/V VDIFF = +1.0 to -1.0V, Vcm = 6V, Low Range Mode 1.95 2.0 2.05 V/V 0.1 0.1 0.3 0.3 V V 27 µA/V 10 mV Saturation Voltage Low-Side, IOUT = 1mA High-Side, IOUT = -1mA, Referenced to = VIN(+) Input Bias Current at Ref. Input (REF Input - C/S(+))/48kohms, Tj = 25°C 15 21 Sense Buffer CMRR REF Input to IDIF REF, IOUT = ±1mA IOUT = ±1mA, REF Input = 2V to 10V 70 90 IDIF REF to IDIF Out Current IDIF = ± 100µA, IDIF Out = 1V 0.95 1.0 1.05 A/A Ratio IDIF = ±1mA, IDIF Out = 1V IDIF Out = ± 1mA, VIN(+) = 4V to 15V,REF Input = 2V IOUT = ±1mA, REF Input = 2V to10V, IDIF Out = 1V 0.94 1.0 1.06 A/A 1.0 5.0 µA/V 1.0 5.0 µA/V 0.6 1.1 1.7 V -1.0 -0.5 0.6 1.1 1.7 V 50 100 µA 0.6 1.1 1.7 V 50 100 µA 0.02 0.1 V Load Current Sense and Rectification Sense Buffer Offset Voltage IDIF Out Supply Sensitivity IDIF Out Common Mode Sensitivity (delta IDIF Out/delta REF Input) dB Auxiliary Functions Inhibit Input Threshold Inhibit Input Current Inhibit Input = 1.7V O/C Force Input Threshold O/C Force Input Current O/C Force Input = 1.7V Range Input Threshold Range Input Current Range Input = 1.7V COMP ADJ Pin Saturation Range Input = 0V, Pin Current = ±500µA, Referenced Voltage to AOUT COMP ADJ Leakage Current Range Input = 1.7V, Supplies = 12V AOUT-VComp Adj = ±6V Total Supply Current When Inhibited VIN(+) and VC(+) currents Thermal Shutdown Temperature 1.0 165 3 µA 5.0 µA 1.5 mA °C UC3178 PIN DESCRIPTIONS: IDIF REF: Output of the IDIF sense buffer. Voltage on this pin will track the applied voltage on the REF Input pin. Current through this pin is full wave rectified and appears as a current sourced from the IDIF OUT pin. A & B OUT: Outputs for the A & B power amplifiers, providing differential drive to the load during normal operation. During a UVLO, Inhibit, or O/C condition both of these outputs will be in a high, source only state. Highside diodes are included to catch inductive load currents flowing into these pins, inductive kicks on the low-side are caught by the high-side output transistors. Inhibit : A high impedance logic input that disables the A and B power amplifiers, the IDIF sense buffer, and the Current Sense amplifier. This input has an internal pull-up AIN(+): Non-inverting input to the A amplifier. Normally tied that will inhibit the device if the input is left open. to the REF Input when the current sense amplifier is used. O/C Force: Logic input that forces the O/C condition. AIN(-): Inverting input to the A amplifier. Used as the sum- O/C IND: Open collector ouput that indicates, with an acming node to close the loop on the overall power tive low state, an O/C condition. amplifier. O/C Sense: Input to the Over Current Comparator. When BIN(+): Non-inverting input to the B amplifier. This pin nor- this input is above its 1V threshold the low-side devices of mally sets the reference point for the differential voltage both the A & B power amplifiers will be disabled forcing a swing at the load. high, source only, state at both outputs. BIN(-): Inverting input to the B amplifier. Used to program PWR GND: Current return for all high level circuitry, this the gain of the B amplifier. pin should be connected to the same potential as GND. COMP ADJ: The compensation adjust pin allows the user to provide an auxiliary compensation network for the A amplifier that is only active when the current sense amplifier is in the low range. With this option, the user can control the change in bandwidth that would otherwise result from the gain change in the feedback loop. Range: When this pin is open or at a logic low potential, the current sense amplifier will be in its low range mode. In this mode the voltage gain of the amplifier will be 2. If this pin is brought to a logic high, the gain of the current sense amplifier will change into its high range value of 0.5. This factor of four change in gain will vary the overall transconductance of the power amplifier by the same ratio, with the transconductance being the highest in the high mode. This feature allows improved dynamic range of load current control for a given control input range and resolution. C/S(+): The non-inverting input to the current sense amplifier is typically tied to the load side of the series current sense resistor. This pin can be pulled below ground during an abrupt load current change with an inductive load. Proper operation of the current sense amplifier will result if this pin does not go below ground by an amount greater REF Input: Sets the Reference level at the C/S Output, than: and is normally tied to the system reference level for in(REF Input / 2 ) - 0.3V. puts to the power amplifier. C/S(-): The inverting input to the current sense amplifier is V IN(+): Provides bias supply to the device. The High-Side typically tied to the connection between the B amplifier drive to the power stages on both the A and B amplifiers output and the current sense resistor that is in series with is referenced to this pin. The High-side saturation voltthe load. ages, and UVLO are specified and measured with respect C/S Output: The output of the current sense amplifier has to this supply pin. a 1.5mA current source pull-up and an active NPN pull- V C(+): This supply pin is the high current supply to the down. The output will pull to within 0.3V of either rail with collectors of the high-side NPN output devices on the A a load current of less than 1mA. and B amplifiers. This supply should be powered whenGND: Reference point for the internal reference, O/C ever the A or B amplifiers are to be activated. This pin can comparator, and other low-level circuitry. operate approximately 400mV below the VIN(+) supply IDIF OUT: Current source output pin. The value of the out- without affecting the voltage available to the load. put current is nominally equal to the magnitude of the current through the IDIF REF pin. 4 UC3178 TYPICAL APPLICATION UDG-92009 Power amplifier transconductance 1 Il RB Go = = • Vs RA AV CS • RS where: Il is the load current Vs is the input command voltage AVCS is the current sense amplifier gain = 2.0 in low range mode = 0.5 in high range mode VO/C is the 1.0V over-current comparator threshold Peak commanded load current RD IlMAX = Vo/c • RS • AVCS • RE UNITRODE INTEGRATED CIRCUITS 7 CONTINENTAL BLVD.• MERRIMACK, NH 03054 TEL (603) 424-2410 • FAX (603) 424-3460 5 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. 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