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
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UC1637 |
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UC2637 |
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CONNECTION DIAGRAM |
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UC3637 |
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DIL-18 (TOP VIEW) |
PLCC-20, LCC-20 |
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J or N Package |
(TOP VIEW) |
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Q, L Packages |
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PACKAGE PIN |
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FUNCTION |
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FUNCTION |
PIN |
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+VTH |
1 |
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CT |
2 |
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-VTH |
3 |
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AOUT |
4 |
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-VS |
5 |
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N/C |
6 |
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+VS |
7 |
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BOUT |
8 |
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+BIN |
9 |
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SOIC-20 (TOP VIEW) |
-BIN |
10 |
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-AIN |
11 |
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DW Package |
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+AIN |
12 |
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+C/L |
13 |
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-C/L |
14 |
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SHUTDOWN |
15 |
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N/C |
16 |
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+E/A |
17 |
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-E/A |
18 |
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E/A OUTPUT |
19 |
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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 |
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UC3637 |
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UNITS |
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MIN |
TYP |
MAX |
MIN |
TYP |
MAX |
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Oscillator |
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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, |
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5 |
7 |
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5 |
7 |
% |
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VPIN 3 = -3V |
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Temperature Stability |
Over Operating Range (Note 3) |
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0.5 |
2 |
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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 |
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-10 |
-0.5 |
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μA |
+VTH, -VTH Input Range |
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+VS-2 |
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-VS+2 |
+VS-2 |
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-VS+2 |
V |
Error Amplifier |
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Input Offset Voltage |
VCM = 0V |
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1.5 |
5 |
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1.5 |
10 |
mV |
Input Bias Current |
VCM = 0V |
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0.5 |
5 |
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0.5 |
5 |
μA |
Input Offset Current |
VCM = 0V |
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0.1 |
1 |
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0.1 |
1 |
μA |
Common Mode Range |
VS = ±2.5 to 20V |
-VS+2 |
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+VS |
-VS+2 |
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+VS |
V |
Open Loop Voltage Gain |
RL = 10k |
75 |
100 |
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80 |
100 |
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dB |
Slew Rate |
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15 |
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15 |
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V/μS |
Unity Gain Bandwidth |
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2 |
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2 |
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MHz |
CMRR |
Over Common Mode Range |
75 |
100 |
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75 |
100 |
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dB |
PSRR |
VS = ±2.5 to ±20V |
75 |
110 |
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75 |
110 |
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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 |
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UC3637 |
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UNITS |
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MIN |
TYP |
MAX |
MIN |
TYP |
MAX |
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Error Amplifier (Continued) |
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Output Sink Current |
VPIN 17 = 0V |
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-50 |
-20 |
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-50 |
-20 |
mA |
Output Source Current |
VPIN 17 = 0V |
5 |
11 |
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5 |
11 |
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mA |
High Level Output Voltage |
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13 |
13.6 |
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13 |
13.6 |
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V |
Low Level Output Voltage |
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-14.8 |
-13 |
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-14.8 |
-13 |
V |
PWM Comparators |
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Input Offset Voltage |
VCM = 0V |
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20 |
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20 |
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mV |
Input Bias Current |
VCM = 0V |
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2 |
10 |
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2 |
10 |
μA |
Input Hysteresis |
VCM = 0V |
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10 |
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10 |
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mV |
Common Mode range |
VS = ±5V to ±20V |
-VS+1 |
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+VS-2 |
-VS+1 |
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+VS-2 |
V |
Current Limit |
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Input Offset Voltage |
VCM = 0V, TJ = 25°C |
190 |
200 |
210 |
180 |
200 |
220 |
mV |
Input Offset Voltage T.C. |
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-0.2 |
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-0.2 |
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mV/°C |
Input Bias Current |
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-10 |
-1.5 |
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-10 |
-1.5 |
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μA |
Common Mode Range |
VS = ±2.5V to ±20V |
-VS |
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+VS-3 |
-VS |
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+VS-3 |
V |
Shutdown |
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Shutdown Threshold |
(Note 4) |
-2.3 |
-2.5 |
-2.7 |
-2.3 |
-2.5 |
-2.7 |
V |
Hysteresis |
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40 |
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40 |
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mV |
Input Bias Current |
VPIN 14 = +VS to -VS |
-10 |
-0.5 |
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-10 |
-0.5 |
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μA |
Under-Voltage Lockout |
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Start Threshold |
(Note 5) |
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4.15 |
5.0 |
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4.15 |
5.0 |
V |
Hysteresis |
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0.25 |
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0.25 |
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mV |
Total Standby Current |
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Supply Current |
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8.5 |
15 |
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8.5 |
15 |
mA |
Output Section |
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Output Low Level |
ISINK = 20mA |
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-14.9 |
-13 |
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-14.9 |
-13 |
V |
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ISINK = 100mA |
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-14.5 |
-13 |
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-14.5 |
-13 |
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Output High Level |
ISOURCE = 20mA |
13 |
13.5 |
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13 |
13.5 |
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V |
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ISOURCE = 100mA |
12 |
13.5 |
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12 |
13.5 |
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Rise Time |
(Note 3) CL = Inf, TJ = 25°C |
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100 |
600 |
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100 |
600 |
ns |
Fall Time |
(Note 3) CL = Inf, TJ = 25°C |
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100 |
300 |
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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