UNITRODE UC1637, UC2637, UC3637 Technical data

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.

6/97

 

 

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

2

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.

3

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