Texas Instruments UC494AN, UC494AJ883B, UC494AJ, UC494ACN, UC494ACJ Datasheet

Advanced Regulating Pulse Width Modulators

FEATURES

• Dual Uncommitted 40V, 200mA
Output Transistors

• 1% Accurate 5V Reference

• Dual Error Amplifiers

• Wide Range, Variable Deadtime

• Single-ended or Push-pull

Operation

• Under-voltage Lockout With
Hysteresis

• Double Pulse Protection

• Master or Slave Oscillator

Operation

• UC495A: Internal 39V Zener Diode

• UC495A: Buffered Steering Control

DESCRIPTION

This entire series of PWM modulators each provide a complete pulse width
modulation system in a single monolithic integrated circuit. These devices in ­clude a 5V reference accurate to ±1%, two independent amplifiers usable for
both voltage and current sensing, an externally synchronizable oscillator
with its linear ramp generator, and two uncommitted transistor output
switches. These two outputs may be operated either in parallel for single­ended operation or alternatin g for push-pull applications with an externally
controlled d ead-band. These unit s are internally protected agains t double­pulsing of a si ngle output or from e xtraneous output signals when the input
supply voltage is below minimum.

The UC495A contains an on-chip 39V zener diode for high-voltage applica­tions where VCC woul d be greater than 40V, and a buffered output steering
control that overrides the internal control of the pulse steering flip-flop.

The UC494A is packaged in a 1 6-pi n DIP, while the UC495A is packaged in
an 18 pin DIP. The UC494A, UC495A are specified for operation over the full
military temperature range of -55°C to +125°C, while the UC494AC,
UC495AC are designed for industrial applications from 0°C to +70°C.

BLOCK DIAGRAM

UC494A/AC
UC495A/AC

10/93

CONNECTION DIAGRAMS

DIL-18 (TOP VIEW)
J or N Package

DIL-18 (TOP VIEW)
J or N Package

UC494A/AC
UC495A/AC

ABSOLUTE MAXI MUM RATING S (Note 1, 2, 3)

Supply Voltage, V CC (Note 2). . . . . . . . . . . . . . . . . . . . . . . . 45V

Amplifier Input Voltages . . . . . . . . . . . . . . . . . . . . . . V

CC + 0.3V

Collector Output Volt age . . . . . . . . . . . . . . . . . . . . . . . . . . . 41V

Collecto r Out put Current. . . . . . . . . . . . . . . . . . . . . . . . . 250mA

Continuous Tot al Diss ip at io n . . . . . . . . . . . . . . . . . . . . 1000mW

@ (or below) 25°C free air temp era tu re range (Note 3)

Storage Temperature Range . . . . . . . . . . . . . . . -65° to +150°C

Lead Temperature 1/16 " (1. 6mm) from case for 60 seconds,

J Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300°C

Lead Temperature 1/16 " (1. 6mm) from case for 10 seconds,

N Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C

Note 1: Over operat in g free air tempe rat ur e range un le ss

otherwis e noted.

Note 2: All voltage values are with respect to network

ground termina l 3.

Note 3: Consult Packaging Sec tion of Databook r egar ding

thermal specifica tion s and limitat ions of package s.

RECOMMENDED OPERAT ING CONDITI ONS

Supply Voltage V CC . . . . . . . . . . . . . . . . . . . . . . . . . . 7V to 40V

Err or Ampl ifier Input V oltage s . . . . . . . . . . . . . -0.3V to V

CC-2V

Collector Output Volt age . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V

Collector Out put Curren t (each transist or ). . . . . . . . . . . 200mA

Current in to F eedback Term inal. . . . . . . . . . . . . . . . . . . . 0.3mA

Timing Capacit or, C

T . . . . . . . . . . . . . . . . . 0.47nF to 10,000nF

Timing Resistor, R

T . . . . . . . . . . . . . . . . . . . . . 1.8kΩ to 500kΩ

Oscillator Frequency . . . . . . . . . . . . . . . . . . . . 1kHz to 300kHz

Operating Free Air Temperature

UC494A, UC495A . . . . . . . . . . . . . . . . . . . . -55°C to +125°C

UC494AC, UC495AC. . . . . . . . . . . . . . . . . . . . 0°C to +70°C

ELECTRICAL CHARACTERISTICS:

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Reference Sec tio n

Output Volt age V

REF IO = 1mA, TA = 25 ° C4.9555.05V

Input Regulation V

CC = 7V to 40V 2 25 mV

Output Regulation I

O = 1mA to 10m A 1 15 mV

Output Voltage O ve r Tempe rat ure ∆T

A = Min. to Max. 4.90 5.10 V

Short Circuit Output Current V

REF = 0, TA = 25°C (Note 1) 10 35 50 mA

Oscillato r Sect io n

Frequency (Not e 2) C

T = 0.01µF, RT = 12kΩ 10 kHz

Standard Deviation Of Freque ncy ( Not e 3) All Values of V

CC, CT, RT, TA Constant 10 %

Frequency Cha nge W ith Voltag e V

CC = 7V to 40V, TA = 25°C0.1%

Frequency Cha nge W ith Tem per ature C

T = 0.01µF, RT = 12kΩ, ∆TA = Min. to Max. 2 %

Deadtime Control Secti on (O u tp ut Cont rol Conn ect ed to V

REF)

Input Bias Curren t (Pin 4) V

(PIN 4) = 0V to 5.25V -2 - 1 0 µA

Maximum Duty-Cycle (Each Output) V

(PIN 4) = 0V 45 %

Unless otherwise stated , ov er recomm end ed ope rat ing fre e-a ir temp era tu re range ,
V

CC = 15V, f = 10kHz, TA = TJ.

UC494A/AC

UC495A/AC

2

ELECTRICAL CHARACTERISTICS:

PARAMETER TEST CONDITION MIN TYP MAX UNITS

Deadtime Control Secti on (c ont .) (Outpu t Control Connect ed to V

REF)

Input Thresh old Volta ge (Pin 4) Zero Duty-Cycle 3 3.3 V

Maximum Duty-Cycle 0 V

Amp lifi e r S e ctio n

Input Offs et Vo lta g e V

O (PIN 3) = 2.5V 2 10 mV

Input Offs et Cu rr ent V

O (PIN 3) =2.5 V 25 250 nA

Input Bias Cur ren t V

O (PIN 3) = 2. 5 V -0.2 -1 µ A

Common-Mo de Input Voltage Range V

CC = 7V to 40V .03 to

V

CC -2

V

Open Loop Voltage Gain ∆V

O = 3V, VO = 0.5V t o 3. 5 V 70 95 dB

Unity Gain Bandwidth 800 kHz
Common-Mo de Reject ion Rat i o V

CC = 40V, TA = 25°C6580dB

Output Sink Curren t (P in 3) V

ID = -15mV to -5V, V (PIN 3) = 0.7V 0.3 0.7 mA

Output Source Cur re nt (Pin 3) V

ID = 15mV to 5V, V(PIN 3) = 3.5V -2 mA

Output Section

Collector Off-State Current V

CE = 40V, VCC = 40V 2 100 µA

Emitter Off-State Curre nt V

CC = VC = 40V, VE = 0 -100 µA

Collector - Emitter
Saturation Voltage

Common-Emit t er V

E = 0, IC = 200mA 1.1 1.3 V

Emitter-Follower V

C = 15V, IE = -200mA 1.5 2.5 V

Output Cont rol Input Curr ent V

I = VREF 3.5 mA

PWM Comparator Section

Input Thresh old Volta ge (Pin 3) Zero Duty-Cycle 4 4.5 V
Input Sink Curren t (Pin 3) V

(PIN 3) = 0.7V 0.3 0.7 mA

Steering Control (UC495A, See Function Table)

Input Current V

(PIN 13) = 0.4V, Q1 ACTIVE -200 µA

V

(PIN 13) = 2.4V, Q2 ACTIVE 300 µA

Deadband 500 mV

Zener Diode Circuit (UC495A)

Breakdown Voltage V

CC = 45V, IZ = 2mA 36 39 45 V

Sink Current V

(PIN 15) = 1V 0.2 0.3 0.6 mA

Total Device

Standby Supply Curre nt Pin 6 at V

REF, All other inputs and

outputs open

VCC = 15V 6 10 mA
V

CC = 40V 9 15 mA

Under Voltage Lockout 3.5 6.5 V
Hysteresis 300 mV

Switchin g Char act erist ics (T

A = 25°C)

Output Voltage Rise Tim e Common-Emit t er Configu rati on 100 200 ns
Output Voltage F a ll Time R

L = 68Ω, CL = 15pF 25 100 ns

Output Voltage Rise Tim e Emitter-Follower Configur ation 100 200 ns
Output Voltage F a ll Time R

L = 68Ω, CL=15pF 40 100 ns

Note 1: Duration of the short circuit should not exce ed one second.
Note 2: Frequenc y for other values of C

T

and R

T i

s approximately

f

=

1.1

RTCT

Note 3: Standard deviation is a measure of the statistical distribution about the mean as derived from the formula:

σ =

√

n

Σ (

X

n

− X)

2

n

= 1

n

− 1

.

UC494A/AC
UC495A/AC

Unless otherw ise stat ed, over rec om mended oper at ing free- air t em per atur e ran ge,
V

CC = 15V, f = 10kHz, TA = TJ.

3

UNITRODE INTEGRATED CIRCUITS
7 CONTINENTAL BLVD. •MERRIMACK, NH 03054
TEL. [phone] • FAX [phone]

Figure 6. Error Amplifi er Sensi n g Techn i que s

Figure 4. Internal Bu ffer wi th Deadb and for

Steering Control on UC495A

Figure 5. Operation with VIN > 40V Using Internal Zener

Figure 1. Slaving Two or More Con tro l Circuit s

Figure 2. Output Ci rcuit of Error Amplif iers

Figure 3. Output Con n ecti ons fo r Singl e-En d ed an d Push -Pu ll Confi gu rati ons

UC494A/AC
UC495A/AC

4

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