UNITRODE UC1637, UC2637, UC3637 Technical data

UC3637N

UC1637

UC2637

UC3637

Switched Mode Controller for DC Motor Drive

FEATURES

∙Single or Dual Supply Operation

∙±2.5V to ±20V Input Supply Range

∙±5% Initial Oscillator Accuracy; ± 10% Over Temperature

∙Pulse-by-Pulse Current Limiting

∙Under-Voltage Lockout

∙Shutdown Input with Temperature Compensated 2.5V Threshold

∙Uncommitted PWM Comparators for Design Flexibility

∙Dual 100mA, Source/Sink Output Drivers

BLOCK DIAGRAM

DESCRIPTION

The UC1637 is a pulse width modulator circuit intended to be used for a variety of PWM motor drive and amplifier applications requiring either uni-directional or bidirectional drive circuits. When used to replace conventional drivers, this circuit can increase efficiency and reduce component costs for many applications. All necessary circuitry is included to generate an analog error signal and modulate two bi-directional pulse train outputs in proportion to the error signal magnitude and polarity.

This monolithic device contains a sawtooth oscillator, error amplifier, and two PWM comparators with ±100mA output stages as standard features. Protection circuitry includes under-voltage lockout, pulse-by-pulse current limiting, and a shutdown port with a 2.5V temperature compensated threshold.

The UC1637 is characterized for operation over the full military temperature range of -55°C to +125°C, while the UC2637 and UC3637 are characterized for -25°C to +85°C and 0°C to +70°C, respectively.

ABSOLUTE MAXIMUM RATINGS (Note 1)

Supply Voltage (±Vs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20V Output Current, Source/Sink (Pins 4, 7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500mA Analog Inputs (Pins 1, 2, 3, 8, 9, 10, 11 12, 13, 14, 15, 16) . . . . . . . . . . . . . . . . . . . . . . . ±Vs Error Amplifier Output Current (Pin 17) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20mA Oscillator Charging Current (Pin 18). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -2mA Power Dissipation at TA = 25°C (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000mW Power Dissipation at TC = 25°C (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000mW Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65°C to +150°C Lead Temperature (Soldering, 10 Seconds). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C

Note 1: Currents are positive into, negative out of the specified terminal.

Note 2: Consult Packaging Section of Databook for thermal limitations and considerations of package.

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			UC1637
			UC2637
	CONNECTION DIAGRAM		UC3637
	DIL-18 (TOP VIEW)	PLCC-20, LCC-20
	J or N Package	(TOP VIEW)
		Q, L Packages
		PACKAGE PIN
		FUNCTION
		FUNCTION	PIN
		+VTH	1
		CT	2
		-VTH	3
		AOUT	4
		-VS	5
		N/C	6
		+VS	7
		BOUT	8
		+BIN	9
	SOIC-20 (TOP VIEW)	-BIN	10
		-AIN	11
	DW Package
		+AIN	12
		+C/L	13
		-C/L	14
		SHUTDOWN	15
		N/C	16
		+E/A	17
		-E/A	18
		E/A OUTPUT	19
		ISET	20

ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA = -55°C to +125°C for the UC1637; -25°C to +85°C for the UC2637; and 0°C to +70°C for the UC3637; +V S = +15V, -VS = - 15V, +VTH = 5V, -VTH = -5V, RT = 16.7kΩ, CT = 1500pF, TA=TJ.

PARAMETER	TEST CONDITIONS	UC1637/UC2637				UC3637		UNITS
		MIN	TYP	MAX	MIN	TYP	MAX
Oscillator
Initial Accuracy	TJ = 25°C (Note 6)	9.4	10	10.6	9	10	11	kHz
Voltage Stability	VS = ±5V to ±20V, VPIN 1 = 3V,		5	7		5	7	%
	VPIN 3 = -3V
Temperature Stability	Over Operating Range (Note 3)		0.5	2		0.5	2	%
+VTH Input Bias Current	VPIN 2 = 6V	-10	0.1	10	-10	0.1	10	μA
-VTH Input Bias Current	VPIN 2 = 0V	-10	-0.5		-10	-0.5		μA
+VTH, -VTH Input Range		+VS-2		-VS+2	+VS-2		-VS+2	V
Error Amplifier
Input Offset Voltage	VCM = 0V		1.5	5		1.5	10	mV
Input Bias Current	VCM = 0V		0.5	5		0.5	5	μA
Input Offset Current	VCM = 0V		0.1	1		0.1	1	μA
Common Mode Range	VS = ±2.5 to 20V	-VS+2		+VS	-VS+2		+VS	V
Open Loop Voltage Gain	RL = 10k	75	100		80	100		dB
Slew Rate			15			15		V/μS
Unity Gain Bandwidth			2			2		MHz
CMRR	Over Common Mode Range	75	100		75	100		dB
PSRR	VS = ±2.5 to ±20V	75	110		75	110		dB

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UC1637

UC2637

UC3637

ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA = -55°C to +125°C for the UC1637; -25°C to +85°C for the UC2637; and 0°C to +70°C for the UC3637: V S = +15V, -VS = - 15V, +VTH = 5V, -VTH = -5V, RT = 16.7kΩ, CT = 1500pF, TA=TJ.

PARAMETERS	TEST CONDITIONS	UC1637/UC2637				UC3637		UNITS
		MIN	TYP	MAX	MIN	TYP	MAX
Error Amplifier (Continued)
Output Sink Current	VPIN 17 = 0V		-50	-20		-50	-20	mA
Output Source Current	VPIN 17 = 0V	5	11		5	11		mA
High Level Output Voltage		13	13.6		13	13.6		V
Low Level Output Voltage			-14.8	-13		-14.8	-13	V
PWM Comparators
Input Offset Voltage	VCM = 0V		20			20		mV
Input Bias Current	VCM = 0V		2	10		2	10	μA
Input Hysteresis	VCM = 0V		10			10		mV
Common Mode range	VS = ±5V to ±20V	-VS+1		+VS-2	-VS+1		+VS-2	V
Current Limit
Input Offset Voltage	VCM = 0V, TJ = 25°C	190	200	210	180	200	220	mV
Input Offset Voltage T.C.			-0.2			-0.2		mV/°C
Input Bias Current		-10	-1.5		-10	-1.5		μA
Common Mode Range	VS = ±2.5V to ±20V	-VS		+VS-3	-VS		+VS-3	V
Shutdown
Shutdown Threshold	(Note 4)	-2.3	-2.5	-2.7	-2.3	-2.5	-2.7	V
Hysteresis			40			40		mV
Input Bias Current	VPIN 14 = +VS to -VS	-10	-0.5		-10	-0.5		μA
Under-Voltage Lockout
Start Threshold	(Note 5)		4.15	5.0		4.15	5.0	V
Hysteresis			0.25			0.25		mV
Total Standby Current
Supply Current			8.5	15		8.5	15	mA
Output Section
Output Low Level	ISINK = 20mA		-14.9	-13		-14.9	-13	V
	ISINK = 100mA		-14.5	-13		-14.5	-13
Output High Level	ISOURCE = 20mA	13	13.5		13	13.5		V
	ISOURCE = 100mA	12	13.5		12	13.5
Rise Time	(Note 3) CL = Inf, TJ = 25°C		100	600		100	600	ns
Fall Time	(Note 3) CL = Inf, TJ = 25°C		100	300		100	300	ns

Note 3: These parameters, although guaranteed over the recommended operating conditions, are not 100% tested in production. Note 4: Parameter measured with respect to +VS (Pin 6).

Note 5: Parameter measured at +VS (Pin 6) with respect to -VS (Pin 5). Note 6: RT and CT referenced to Ground.

FUNCTIONAL DESCRIPTION

Following is a description of each of the functional blocks shown in the Block Diagram.

Oscillator

The oscillator consists of two comparators, a charging and discharging current source, a current source set terminal, lSET and a flip-flop. The upper and lower threshold of the oscillator waveform is set externally by applying a voltage at pins +VTH and -VTH respectively. The +VTH ter-

minal voltage is buffered internally and also applied to the lSET terminal to develop the capacitor charging current through RT. If RT is referenced to -VS as shown in Figure 1, both the threshold voltage and charging current will vary proportionally to the supply differential, and the oscillator frequency will remain constant. The triangle waveform oscillators frequency and voltage amplitude is determined by the external components using the formulas given in Figure 1.

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