UNITRODE UC3178 Technical data

UC3178

UC3178

Full Bridge Power Amplifier

FEATURES

∙Precision Current Control

∙±450mA Load Current

∙1.2V Typical Total Vsat at 450mA

∙Programmable Over-Current Control

∙Range Control for 4:1 Gain Change

∙Compensation Adjust Pin for Range Bandwidth Control

∙Inhibit Input and UVLO

∙3V to 15V Operation

∙12mA Quiescent Supply Current

DESCRIPTION

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.

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

ABSOLUTE MAXIMUM RATINGS

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

*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.

		UC3178
CONNECTION DIAGRAM
PLCC - 28 (Top View)	PACKAGE PIN FUNCTION
QP Package	FUNCTION	PIN
	Inhibit	1
	O/C Force	2
	O/C Sense	3
	Range	4
	C/S(+)	5
	Comp Adj	6
	O/C Ind	7
	AIN(+)	8
	AIN(-)	9
	VC(+) Supply	10
	A Output	11
	Pwr Gnd	12
	Pwr Gnd	13
	Pwr Gnd	14
	Pwr Gnd	15
	Pwr Gnd	16
	Pwr Gnd	17
	Pwr Gnd	18
	B Output	19
	VIN(+)	20
	BIN(-)	21
	BIN(+)	22
	REF Input	23
	C/S(+)	24
	C/S Out	25
	IDIF Out	26
	IDIF REF	27
	Ground	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
Input Supply
VIN (+)Supply Current			12	16	mA
VC(+) Supply Current	IOUT = OA		1.2	2.0	mA
Total Supply Current	Supplies = 5V,IOUT = OA		12	16	mA
	Supplies = 12V,IOUT = OA		13	18	mA
VIN(+) UVLO Threshold	low to high		2.6	2.8	V
UVLO Threshold Hysterisis			300		mV
Over-Current (O/C) Comparator
Input Bias Current	V input = 0.8V	-1.0	-.01		μA
Thresholds	low to high	0.97	1.0	1.03	V
Threshold Hysterisis		85	100	115	mV
O/C IND Vsat	IOUT = 5mA, V input low		0.2	0.45	V
O/C IND Leakage	VOUT = 20V			5.0	μA
Power Amplifiers A and B
Input Offset Voltage	A Amplifier, VCM = 6V			4.0	mV
	B Amplifier, VCM = 6V			12.0	mV
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
	to VOUT = 10.5V, IOUT = -300mA	3.0	15.0		V/mV

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