Modulating Regulator. XR-495 Datasheet

XR-495 Regulator. Datasheet pdf. Equivalent

XR-495 Datasheet
Recommendation XR-495 Datasheet
Part XR-495
Description Pulse-Width Modulating Regulator
Feature XR-495; XR-495 Pulse-Width Modulating Regulator GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM The XR-495 .
Manufacture Exar
Datasheet
Download XR-495 Datasheet




Exar XR-495
XR-495
Pulse-Width Modulating Regulator
GENERAL DESCRIPTION
FUNCTIONAL BLOCK DIAGRAM
The XR-495 is a monolithic pulse width modulating reg-
ulator designed to contain all blocks necessary for a
switching regulator. Included in the 16 pin dual in-line
packages is a voltage reference, oscillator, control
logic, error amplifiers, and dual uncommitted outputs.
This device can be used for switching regulators of ei-
ther polarity, polarity converters, transformer coupled
DC to DC converters, transformerless voltage dou-
blers, and many other power control applications. A
39V zener diode allows operation with supply voltages
exceeding 40V. The XR-495M is fully specified for oper-
ation over the full military temperature range from -
55°C to + 125°C, while the XR-495CN and XR-495CP
are designed for commercial applications over O°C to
+ 70 o e.
NON
INV
INPUT
INV
INPUT
FEED
BACK
DEAD
TIME
CONTROL
4
INV
INPUT
REF
OUT
OUTPUT
CONTROL
STEERING
INPUT
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
On-Chip 39-V Zener
External Control of Output Steering
APPLICATIONS
Pulse-Width Modulated Power Control Systems
Switching Regulators
ORDERING INFORMATION
Part Number
Package
Operating Temperature
XR-495M
XR-495CN
XR-495CP
Ceramic
Ceramic
Plastic
- 55°C to + 125°C
O°C to + 70°C
O°C to + 70°C
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 mA
41 Volts
41 Volts
1000 mW
Cl
El
SYSTEM DESCRIPTION
All functions required to construct a pulse-width modu-
lating regulator are incorporated on a single monolithic
chip in the XR-495. 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-495 architecture prohibits the
possibility of either output being pulsed twice during
push-pull operation. The internal amplifier's circuitry al-
lows 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 os-
cillator may be used to drive the common XR-495 cir-
cuitry and provide a sawtooth input for associated con-
trol circuitry in synchronous multiple-rail power sup-
plies, or may be bypassed by terminating RT (Pin 6) to
the reference output and providing a sawtooth input to
CT (Pin 5).
The XR-495 also contains an on-chip 39 volt zener di-
ode for high voltage applications where VCC is greater
than 40 volts, and an output steering control that over-
rides the internal control of the pulse steering flip-flop.
5-126



Exar XR-495
ELECTRICAL CHARACTERISTICS
Test Conditions: TA = 25°C, unless specified otherwise.
XR-495
PARAMETERS
Reference Section
Output Voltage (Vref)
Input Regulation
Output Regulation
Output Voltage Change
with Temperature
Short Circuit Output 1 Current
Oscillator Section
Frequency
Standard Deviation2 of
Frequency
Frequency Change with Voltage
Frequency Change with
Temperature
Dead Time Control Section
(See Figure 2)
Input Bias Current (Pin 4)
Maximum Duty Cycle
(each output)
Input Threshold Voltage (Pin 4)
MIN TYP
4.75
10
5.0
2.0
1
0.2
35
10
10
0.1
-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)
Output Section
Collector Off-State Current
Emitter Off-State Current
Collector-Emitter Saturation
Voltage Common-Emitter
-0.3 to
VCC -2
70
65
0.3
-2
2
25
0.2
95
800
80
0.7
2
1.1
Emitter-Follower
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
XR·495
MAX
5.25
25.0
15
1
50
2
UNIT
V
mV
mV
%
mA
kHz
%
%
%
CONDITIONS
10 = 1mA
VCC = 7V to 40V
10 = 1 to 10mA
~TA = Min to Max
Vref = 0
CT = 0.01 !J., RT = 12kn
VCC, CT, RT, TA; all values constant
VCC = 7V to 40V
CT = 0.01!J. F, RT = 12kn,
~TA = Min to Max
-10 !J.A
%
3.3 V
10 mV
250 nA
1 !J.A
V
dB
kHz
dB
mA
mA
100
-100
!J.A
!J.A
1.3 V
2.5 V
3.5 mA
4.5 V
mA
10 mA
15 mA
mA
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
VID = -15mV to -5V, V (Pin 3) = 0.7V
VID = 15mV to 5V, V (Pin 3) = 3.5V
VCE = 40V, Vce = 40V
VCC = Ve = 40V, VE = 0,
XR-494M Max = - 15O!J.A
VE = 0, IC = 200mA,
XR-494M Max = 1.5V
Ve = 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)
II
1. Duration of the short circuit should not exceed one second.
2. Standard deviation is a measure of the statistical distribution about the mean as derived from the formula a =.
SWITCHING CHARACTERISTICS TA = 25°C
PARAMETER
MIN
Typ1
MAX.
UNIT
Output Voltage Rise Time
Output Voltage Fall Time
100 200
25 100
ns
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.
5-127
TEST CONDITIONS
Common-Emitter Configuration,
See Figure 1
Emitter-Follower Configuration,
See Figure 2



Exar XR-495
XR·495
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-495M
MIN MAX
7 40
-0.3
VCC-2
40
200
0.3
0.47 10,000
1.8 500
1 300
-55 125
XR-495CN
XR-495CP
MIN MAX
7 40
-0.3
VCC-2
40
200
0.3
0.47 10,000
1.8 500
1 300
0 75
r-----------,
(EACH OUTPUT
CIRCUIT)
I
I
.,w"
CL. 15 pI'
(INCLUDES PROBE AND
JIG C.P....CIT.NCE)
I
IL __________ .JI
A) TEST CIRCUIT
,---------1
: (EA~I~g~~uT
I
I ,-~I__--~
I
I
I
I
I
I
I
IL _________ .JI
CL" 150 pF
(INCLUDES PROBE AND
JIG CAPACITANCE)
.,w"
UNIT
V
V
V
mA
mA
nF
kO
kHz
°C
HI OUTPUT YOLlAGE WAvEFORM
Figure 1. Common-Emitter Configuration
TEST (
INPUTS
VCC·15V
I SOli
2W
OUTPUT I
OUTPUT :2
(OPEN)
(O;;O:;';i
A) TES T CIRCUIT
Figure 3. Dead-Time and Feedback Control
VOLTAGE
ATCI
VOLTAGE
AT C2
VOLTAGE
AT CT
O£it.i)..iiili~
CONTROL
INPUT
OV I
I
I
fEEDBACK
I
I
I
O.7V
DUTY
CYCLE
MAX
5-128
,,--+I --1
BI OUTPUT VOLTAGE WAVEFORM
Figure 2. Emitter-Follower Configuration
r---.~----.----Vce
,....-_•-..--_- _0 _ - Vce
--- 0
8) VOLTAGE WAVEfORMS







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