UNITRODE UC1638, UC2638, UC3638 Technical data

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Advanced PWM Motor Controller

UC1638
UC2638
UC3638

FEATURES

• Single or Dual Supply Operation

• Accurate High Speed Oscillator

• Differential X5 Current Sense

Amplifier

• Bidirectional Pulse-by-Pulse
Current Limiting

• Programmable Oscillator
Amplitude and PWM Deadband

• Dual 500mA Totem Pole Output
Drivers

• Dual 60V, 50mA Open Collector
Drivers

• Undervoltage Lockout

BLOCK DIAGRAM

DESCRIPTION

The UC1638 family of integrated circuits are advanced pulse width modula­tors intended for a variety of PWM motor drive and amplifier applications re­quiring either uni-directional or bi-directional drive circuits. Similar in
architecture to the UC1637, 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.

Key features of the UC1638 include a programmable high speed triangle os­cillator, a 5X differential current sensing amplifier, a high slew rate error am­plifier, high speed PWM comparators, and two 50mA open collector as well
as two±500mA totem pole output stages. The individual circuit blocks are
designed to provide practical operation to switching frequencies of 500kHz.

Significant improvements in circuit speed, elimination of many external pro­gramming components, and the inclusion of a differential current sense am­plifier, allow this controller to be specified for higher performance
applications, yet maintain the flexibility of the UC1637. The current sense
amplifier in conjunction with the error amplifier can be configured for average
current feedback.The additional open collector outputs provide a drive signal

continued

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UDG-95048-4

UC1638

UC1638
UC2638

UC2638
UC3638

UC3638

DESCRIPTION (cont.)

for the highside switches in a full bridge configuration.
The programmable AREFIN pin allows for single or dual
supply operation. Oscillator ramp amplitude and PWM
deadband are programmable by tapping a voltage di­vider off the 5V reference to the appropriate program­ming input (PVSET or DB).

Additional features include a precision externally avail­able 5V reference, undervoltage lockout, pulse-by-pulse
peak current limiting, and a remote shutdown port. The
UC1638 family is available in the 20 pin N, DW and J
packages. Consult the factory for other packaging op­tions.

CONNECTION DIAGRAMS

DIL-20 (Top View)
NorJPackage

ABSOLUTE MAXIMUM RATINGS

Supply Voltage VCC (referenced to VEE) .............40V

Output Drivers (AOUT2, BOUT2)

Currents (continuous) ........................±0.25A

Currents (peak) ............................±500mA

REF Output Current ....................Internally Limited

PVSET, DB, RT, INV, REF, CSOUT .............0.3to10V

CS+, CS- .............................VEE–1V to VCC

CT, AREF, AREFIN, COMP, SD ................VEE−0.3

Output Voltage (AOUT1, BOUT1) ....................60V

Storage temperature....................−65°C to +150°C

Junction Temperature...................−55°C to +150°C

Lead temperature (soldering, 10 sec.)..............+300°C

Currents are positive into, negative out of the specified termi­nal. Consult packaging section of data book for thermal limita­tion considerations of packages.

SOIC-20 (Top View)
DW Package

PLCC-20 (Top View)
Q Package

2

UC1638
UC2638
UC3638

ELECTRICAL CHARACTERISTICS

Unless otherwise specified; VCC = 15V, VEE =–15V, CT = 680pF, RT = 3k,
VPVSET = 1.5V, VCOMP = 0V, VCSOUT = 0V, VDB = REF, VEXTREF = 0V, VSD =
VCC – 3V, TA = −55°C to 125°C for the UC1638, −25°C to 85°C for the UC2638,
0°C to 70°C for the UC3638. TA =TJ.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Overall

Supply Current, Operating 15 23 mA
UVLO Threshold Reference to VEE 9 10 V
UVLO Hysteresis Reference to VEE 1 V

Voltage Amplifier

Input Offset Voltage COMP = 0V −15 0 15 mV

SENSE Bias Current 0 0.5 2

V
Open Loop Gain COMP = −5V to +5V 75 100 dB
CMRR V

CM = −5V to +5V 70 100 dB

PSRR VCM = 0V, VCC − VEE = 10V to 36V 70 90 dB
VOUT High INV = −0.1V, RL = 10k 13 13.6 V

OUT Low INV = +0.1V, RL = 10k −13.8 –13 V

V
Slew Rate Rising and Falling Overdrive =±1V 12 V/µs
Output Source Current COMP Shorted to VEE 5 15 mA
Output Sink Current COMP Shorted to VCC 15 40 mA
Gain Bandwidth Product F

IN = 100kHz, 10mV p-p 1 5 MHz

5V Reference

Output Voltage I

REF = −1mA, TA = 25°C 4.925 5 5.075 V

Output Voltage IREF = −1mA 4.875 5 5.125 V
Load Regulation IREF = −1mA to −10mA −15 2 15 mV
Line Regulation VCC - VEE = 10V to 36V −15 2 15 mV
Short Circuit Current V

REF =0V 15 70 mA

Oscillator

Initial Accuracy T

A = 0°C – 70°C 86 98 110 kHz

Voltage Stability VCC − VEE = 10V to 36V 2 %
Total Variation Line, Temperature 76 98 120 kHz
PVSET Input Bias Current 0.5 3 µA
PVSET Input Voltage Range (Note 1) 0.5 VREF V
Amplitude Limit (Note 1) VEE+3 VCC−3V

AOUT1, BOUT1 Output Drivers

Output Low Voltage I

OUT = 1mA, Ref. to PVE, PVE = 0V 0.9 1.3 V

IOUT = 50mA 1.2 1.8 V

Leakage Current Output Voltage = 50V 0.1 50 µA

AOUT2, BOUT2 Output Drivers

Output High Voltage I

OUT = −20mA, Ref. to PVE, PVE = 0V 12.2 13.5 V
OUT = −100mA, Ref. to PVE, PVE = 0V 12 13.5 V

I
Output High Clamp Level IOUT = −20mA, Ref. to PVE, PVE = VEE 14.4 16.5 V
Output Low Voltage IOUT = 20mA, Ref. to PVE, PVE = 0V 0.4 1 V

OUT = 100mA, Ref. to PVE, PVE = 0V 0.6 2.2 V

I
Output Rise Time COUT = 1nF 50 100 ns
Output Fall Time COUT = 1nF 50 100 ns

m

A

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