Modulating Regulator. XR-494 Datasheet

XR-494 Regulator. Datasheet pdf. Equivalent


Exar XR-494
XR-494
Pulse-Width Modulating Regulator
GENERAL DESCRIPTION
FUNCTIONAL BLOCK DIAGRAM
The XR-494 is a monolithic pulse width modulating reg-
ulator designed to contain all the blocks necessary for
a switching regulator. Included in a 16 pin dual in-line
package is a voltage reference, oscillator, control logic,
error amplifiers, and dual uncommitted outputs. This
device can be used for switching regulators of either
polarity, polarity converters, transformer coupled DC to
DC converters, transformerless voltage doublers, and
many other power control applications. The XR-494M is
fully specified for operation over the full military tem-
perature range from - 55°C to + 125°C, while the XR-
494CN and XR-494CP are designed for commercial ap-
plications over O°C to + 70°C.
FEED
BACK
DEAO
TIME
CONTROL
4 I---! f-----f'
'NV
INPUT
REF
OUT
OUTPUT
CONTROL
FEATURES
Complete PWM Power Control Circuitry
Uncommitted Outputs for 200-mA Sink or Source
Output Control Selects Single-Ended
or Push-Pull Operation
Internal Circuitry Prohibits Double Pulse
at Either Output
Variable Dead Time Provides Control Over Total
Range
Internal Regulator Provides a Stable
5-V Reference Supply
Circuit Architecture Provides Easy Synchronization
APPLICATIONS
Pulse-Width Modulated Power Control Systems
Switching Regulators
ABSOLUTE MAXIMUM RATINGS, TA = 25°C
Amplifier Input Voltages
Output Current
Supply Voltage
Collector Output Voltage
Power Dissipation
Total, at or below 25°C
Ceramic Package
Derate above + 28°C
Plastic Package
Derate above + 41°C
VCC + 0.3 Volts
250 rnA
41 Volts
41 Volts
1000 mW
ORDERING INFORMATION
Part Number
XR-494M
XR-494CN
XR-494CP
Package
Ceramic
Ceramic
Plastic
Operating Temperature
- 55°C to + 125°C
O°C to + 70°C
O°C to + 70°C
SYSTEM DESCRIPTION
All functions required to construct a pulse-width modu-
lating regulator are incorporated on a single monolithic
chip in the XR-494. The device is primarily deSigned for
power supply control and contains a on-chip five volt
regulator, two error amplifiers, an adjustable oscillator,
dead-time control comparator, a pulse-steering flip-flop,
and output control circuits. Either common emitter or
emitter follower output capability is provided by the un-
committed output transistors. Single ended or push-pull
output operation may be selected through the output
control function. The XR-494 architecture prohibits the
possibility of either output being pulsed twice during
push-pull operation. The internal amplifiers's circuitry
allows for a common-mode input voltage range of - 0.3
volt to VCC - 2 volts. The dead time control compara-
tor provides approximately 5% dead time unless the
dead time control is externally driven. The on-Chip
oscillator may be used to drive the common XR-494
circuitry and provide a sawtooth input for associated
control circuitry in synchronous multiple-rail power
supplies, or may be bypassed by terminating RT (Pin 6)
to the reference output and providing a sawtooth input
to CT (Pin 5).
5-122


XR-494 Datasheet
Recommendation XR-494 Datasheet
Part XR-494
Description Pulse-Width Modulating Regulator
Feature XR-494; XR-494 Pulse-Width Modulating Regulator GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM The XR-494 .
Manufacture Exar
Datasheet
Download XR-494 Datasheet




Exar XR-494
ELECTRICAL CHARACTERISTICS
Test Conditions: TA == 25°C, unless otherwise specified.
XR-494
PARAMETERS
MIN TYP
Reference Section
Output Voltage (Vref)
Input Regulation
Output Regulation
Output Voltage Change
with Temperature
Short Circuit Output1
Current
4.75 5.0
2.0
1
0.2
10 35
Oscillator Section
Frequency
Standard Deviation2
of Frequency
Frequency Change with
Voltage
Frequency Change with
Temperature
10
10
0.1
Dead Time Control Section
(See Figure 2)
Input Bias Current (Pin 4)
Maximum Duty Cycle
(each output)
Input Threshold Voltage
(Pin 4)
-2
45
3
Error-Amplifier Sections
Input Offset Voltage
Input Offset Current
Input Bias Current
Common-Mode Input
Voltage Range
Open Loop Voltage
Amplification
Unity Gain Bandwidth
Common·Mode Rejection
Ratio
Output Sink Current
(Pin 3)
Output Source Current
(Pin 3)
-0.3 to
VCC -2
70
65
0.3
·2
2
25
0.2
95
800
80
0.7
Output Section
Collector Off·State Current
Emitter Off·State Current
2
Coliector·Emitter Saturation
Voltage Common·Emitter
1.1
Emitter·Foliower
Output Control Input
Current
PWM Comparator Section
Input Threshold Voltage
(Pin 3)
Input Sink Current (Pin 3)
Total Device
Standby Supply Current
Average Supply Current
1.5
4
0.3 0.7
6
9
7.5
MAX UNIT
5.25 V
25.0 mV
15 mV
1%
50 mA
kHz
%
%
2%
-10 JLA
%
3.3 V
10 mV
250 nA
1 JLA
V
dB
kHz
dB
mA
mA
100
-100
p.A
p.A
1.3 V
2.5 V
3.5 mA
4.5 V
mA
10 mA
15 mA
mA
XR·494
CONDITIONS
10 == 1mA
VCC == 7V to 40V
10 = 1 to lOmA
~TA = Min to Max
Vref = 0
CT = 0.01 JLF, RT = 12kO
VCC, CT, RT, TA;
all values constant
VCC = 7V to 40V
CT = 0.01 JLF, RT == 12kO,
~TA = Min to Max
VI = 0 to 5.25V
VI = 0 (Pin 4)
Zero Duty Cycle, Maximum
Duty Cycle = OV Min
Vo (Pin 3) == 2.5V
Vo (Pin 3) = 2.5V
Vo (Pin 3) = 2.5V
VCC == 7V to 40V
~VO = 3V, Vo =
0.5V to 3.5V
VCC = 40V
V,O == - 15mV to - 5V, V
(Pin 3) = 0.7V
VID == 15mV to 5V, V
(Pin 3) = 3.5V
VCE = 40V, VCC = 40V
VCC = Vc = 40V, VE = 0,
XR·494M Max = - 150p.A
VE == a, Ic = 200mA,
XR·494M Max = 1.5V
Vc == 15V, IE == -200mA
VI = Vref
Zero Duty Cycle
V (Pin 3) == 0.7V
VCC == 15V, Pin 6 at Vref
VCC == 40V, All Other Inputs
and Outputs Open
V = 2V (Pin 4)
5-123



Exar XR-494
XR·494
RECOMMENDED OPERATING CONDITIONS
PARAMETERS
Supply voltage, VCC
Amplifier input voltages, VI
Collector output voltage, Vo
Collector output current
(each transistor)
Current into feedback terminal
Timing capacitor, CT
Timing resistor, RT
Oscillator frequency
Operating free-air temperature, TA
XR-494M
MIN
7
-0.3
MAX
40
VCC -2
40
200
0.47
1.8
1
-55
0.3
10,000
500
300
125
XR-494CN
XR-494CP
MIN
7
-0.3
MAX
40
VCC -2
40
200
0.3
0.47 10,000
1.8 500
1 300
0 75
UNIT
V
V
V
mA
mA
nF
kO
kHz
°c
SWITCHING CHARACTERISTICS TA = 25°C
PARAMETER
MIN. Typ.1
MAX.
UNIT
Output Voltage Rise Time
Output Voltage Fall Time
100 200
ns
25 100 ns
Output Voltage Rise Time
Output Voltage Fall Time
100 200
40 100
ns
ns
1. All typical values except for temperature coefficients are at TA = 25°C.
r
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TEST CONDITIONS
Common-Emitter Configuration.
See Figure 1
Emitter-Follower Configuration,
See Figure 2
'"- .-
"""' 'G' JIEACI'tOUTPUT
1
1_._
I
I
--
I
:(f0"""'I
_______ J
~.~'
Cl I~ 'I'
IINCLUOES'II0lEAND
JIQC",PACIUHCEI
Figure 1. Common-Emitter Configuration
V,
VREF 0-----1
Figure 3. Error-Amplifier Characteristics
Figure 2. Emitter-Follower Configuration
FUNCTION TABLE
INPUTS
OUTPUT CONTROL
OUTPUT FUNCTION
Grounded
At Vref
At Vref
At Vref
Single-ended or parallel output
Normal push-pull operation
PWM Output at 01
PWM Output at 02
5-124





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