UC2901DWTR [TI]
SPECIALTY ANALOG CIRCUIT, PDSO16, SOIC-16;
| 型号： | UC2901DWTR |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | SPECIALTY ANALOG CIRCUIT, PDSO16, SOIC-16 光电二极管 |
| 文件： | 总7页 (文件大小：394K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
UC1901
UC2901
UC3901
Isolated Feedback Generator
FEATURES
DESCRIPTION
• An Amplitude-Modulation System for
Transformer Coupling an Isolated
Feedback Error Signal
The UC1901 family is designed to solve many of the problems associ-
ated with closing a feedback control loop across a voltage isolation
boundary. As a stable and reliable alternative to an optical coupler, these
devices feature an amplitude modulation system which allows a loop er-
ror signal to be coupled with a small RF transformer or capacitor.
• Low-Cost Alternative to Optical
Couplers
The programmable, high-frequency oscillator within the UC1901 series
permits the use of smaller, less expensive transformers which can readily
be built to meet the isolation requirements of today's line-operated power
systems. As an alternative to RF operation, the external clock input to
these devices allows synchronization to a system clock or to the switch-
ing frequency of a SMPS.
• Internal 1% Reference and Error
Amplifier
• Internal Carrier Oscillator Usable to
5MHz
• Modulator Synchronizable to an
External Clock
An additional feature is a status monitoring circuit which provides an active-
±
low output when the sensed error voltage is within 10% of the reference.
• Loop Status Monitor
The DRIVERA output, DRIVERB output, and STATUS output are disabled
until the input supply has reached a sufficient level to allow proper operation
of the device.
Since these devices can also be used as a DC driver for optical couplers,
the benefits of 4.5 to 40V supply operation, a 1% accurate reference, and a
high gain general purpose amplifier offer advantages even though an AC
system may not be desired.
UC1901 SIMPLIFIED SCHEMATIC
µ
µ
µ
UDG-98080
11/98
UC1901
UC2901
UC3901
CONNECTION DIAGRAMS
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . 40V
Reference Output Current . . . . . . . . . . . . . . . . . . . . . . . –10mA
Driver Output Currents . . . . . . . . . . . . . . . . . . . . . . . . . . –35mA
Status Indicator Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V
Status Indicator Current . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
Ext. Clock Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V
Error Amplifier Inputs . . . . . . . . . . . . . . . . . . . . . –0.5V to +35V
Power Dissipation at TA = 25°C. . . . . . . . . . . . . . . . . . 1000mW
Power Dissipation at TC = 25°C . . . . . . . . . . . . . . . . . 2000mW
Operating Junction Temperature . . . . . . . . . . –55°C to +150°C
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 seconds) . . . . . . . . . . 300°C
DIL-14, SOIC-14 (TOP VIEW)
J or N Package, D Package
Note 1: Voltages are referenced to ground, Pin 7. Currents are
positive into, negative out of the specified terminal.
Note 2: Consult Packaging section of Databook for thermal limi-
tations and considerations of package.
PLCC-20, LCC-20 (TOP VIEW)
Q, L Packages
SOIC-16 Wide (TOP VIEW)
DW Package
TEMPERATURE AND PACKAGE SELECTION
GUIDE
TEMPERATURE
RANGE
AVAILABLE
PACKAGES
UC1901
UC2901
UC3901
–55°C to +125°C
–40°C to +85°C
0°C to +70°C
J, L
D, DW, J, N, Q
D, DW, J, N, Q
2
UC1901
UC2901
UC3901
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for VIN = 10V, RT = 10kΩ, CT =
820pF, TA = TJ.
PARAMETER
TEST CONDITIONS
UC1901/UC2901
MIN TYP MAX
UC3901
TYP
UNITS
MIN
MAX
Reference Section
Output Voltage
TJ = 25°C
MIN ≤ TJ ≤ TMAX
1.485
1.470
1.5 1.515 1.47
1.5 1.530 1.455
1.5
1.5
2
1.53
1.545
15
V
T
Line Regulation
VIN = 4.5 to 35V
IOUT = 0 to 5mA
TJ = 25°C
2
4
10
10
mV
mV
mV
Load Regulation
Short Circuit Current
4
15
–35
–55
–35
–55
Error Amplifier Section (To Compensation Terminal)
Input Offset Voltage
Input Bias Current
Input Offset Current
Small Signal Open Loop Gain
CMRR
VCM = 1.5V
VCM = 1.5V
VCM = 1.5V
1
4
–3
1
1
8
–6
2
mV
µA
–1
–1
0.1
60
0.1
60
µA
40
60
80
0.4
90
–2
40
60
80
0.4
90
–2
dB
VCM = 0.5 to 7.5V
VIN = 2 to 25V
80
80
dB
PSRR
100
0.7
150
–3
100
0.7
150
–3
dB
Output Swing, ∆ VO
Maximum Sink Current
Maximum Source Current
Gain Band Width Product
Slew Rate
V
µA
mA
MHz
V/µS
1
1
0.3
0.3
Modulators/Drivers Section (From Compensation Terminal)
Voltage Gain
11
12
13
10
12
±
2.8
14
dB
V
±
±
±
Output Swing
1.6
2.8
1.6
500
–15
Driver Sink Current
500
–15
700
–35
25
700
–35
25
µA
Driver Source Current
mA
MHz
Gain Band Width Product
Oscillator Section
Initial Accuracy
TJ = 25°C
MIN ≤ TJ ≤ TMAX
140
130
150
160
170
.35
130
120
150
170
180
.60
kHz
kHz
%/V
MHz
V
T
Line Sensitivity
VIN = 5 to 35V
.15
5
.15
5
Maximum Frequency
Ext. Clock Low Threshold
Ext. Clock High Threshold
Status Indicator Section
Input Voltage Window
Saturation Voltage
RT = 10k, CT = 10pF
Pin 1 (CT) = VIN
Pin 1 (CT) = VIN
0.5
0.5
1.6
1.6
V
±
±
±
±
±
±
170
@ E/A Inputs, VCM = 1.5V
E/A ∆ Input = 0V, ISINK = 1.6mA
Pin 13 = 3V, E/A ∆ Input = 0.0V
Pin 13 = 40V, E/A ∆Input = 0.2V
VIN = 35V
135
8
150
165
130
8
150
mV
V
0.45
0.45
Max. Output Current
Leakage Current
15
.05
5
15
.05
5
mA
µA
mA
1
8
5
Supply Current
10
UVLO Section
Drivers Enabled Threshold
At Input Supply VIN
At Input Supply VIN
3.9
3.9
4.5
4.5
3.9
3.9
4.5
4.5
V
V
Status Output Enabled
Threshold
Change in Reference Output
When VIN Reaches UVLO
Threshold
–2
–30
–2
–30
mV
3
UC1901
UC2901
UC3901
µ
µ
Note: Transformer Data: N1 = N2 = 20TAWG 26
Core = Ferroxcube 3E2A Ferrite, 0.5" O.D. toroid
Carrier Frequency = 1MHz
Figure 1. Transformer Coupled Open Loop Transfer Function
Figure 2. Oscillator Frequency
APPLICATION INFORMATION
Figure 3. Typical Driver Output Swing vs
Temperature
The error amplifier compensation terminal, Pin 12, is in- With the internal oscillator the squarewave will have a
tended as a source of feedback to the amplifier's invert- fixed 50% duty cycle. If the internal oscillator is disabled
ing input at Pin 11. For most applications, a series DC by connecting Pin 1, C , to V then the frequency and
R
IN
blocking capacitor should be part of the feedback net- duty cycle of the output will be determined by the input
work. The amplifier is internally compensated for unity clock waveform at Pin 2. If the oscillator remains disabled
feedback.
and there is not clock input at Pin 2, there will be a linear
12dB of signal gain to one or the other of the driver out-
puts depending on the DC state of Pin 2.
The waveform at the driver outputs is a squarewave with
an amplitude that is proportional to the error amplifier in-
put signal. There is a fixed 12dB of gain from the error The driver outputs are emitter followers which will source
amplifier compensation pin to the modulator driver out- a minimum of 15mA of current. The sink current, inter-
puts. The frequency of the output waveform is controlled
by either the internal oscillator or an external clock signal.
nally limited at 700µA, can be increased by adding resis-
tors to ground at the driver outputs.
4
UC1901
UC2901
UC3901
APPLICATION INFORMATION (continued)
Figure 4. R.F. Transformer Coupled Feedback
Figure 5. Feedback Coupled at Switching Frequency
5
UC1901
UC2901
UC3901
TYPICAL APPLICATION
UDG-98196
Figure 6. Optically Coupled DC Feedback
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 • FAX (603) 424-3460
6
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