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 associated 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 error signal to be coupled with a small RF transformer or capacitor.
• Low-Cost Alternative to Optical
Couplers
• Internal 1% Reference and Error
Amplifier
• Internal Carrier Oscillator Usable to
5MHz
• Modulator Synchronizable to an
External Clock
• Loop Status Monitor
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 switching frequency of a SMPS.
An additional feature is a status monitoring circuit which provides an activelow output when the sensed error voltage is within ±10% of the reference.
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 SCHEMATICNovember S
µ
µ
µ
UDG-98080
SLUS279A - November 1998 - Revised January 2010
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 limitations 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
UC1901
UC2901
UC3901
TEMPERATURE
RANGE
–55°C to +125°C
–40°C to +85°C
0°C to +70°C
AVAILABLE
PACKAGES
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
Reference Section
Output Voltage
TJ = 25°C
TMIN ≤ TJ ≤ TMAX
Line Regulation
VIN = 4.5 to 35V
Load Regulation
IOUT = 0 to 5mA
Short Circuit Current
TJ = 25°C
Error Amplifier Section (To Compensation Terminal)
Input Offset Voltage
VCM = 1.5V
Input Bias Current
VCM = 1.5V
Input Offset Current
VCM = 1.5V
Small Signal Open Loop Gain
CMRR
VCM = 0.5 to 7.5V
PSRR
VIN = 5 to 25V
Output Swing, ∆ VO
Maximum Sink Current
Maximum Source Current
Gain Band Width Product
Slew Rate
Modulators/Drivers Section (From Compensation Terminal)
Voltage Gain
Output Swing
Driver Sink Current
Driver Source Current
Gain Band Width Product
Oscillator Section
Initial Accuracy
TJ = 25°C
TMIN ≤ TJ ≤ TMAX
Line Sensitivity
VIN = 5 to 35V
Maximum Frequency
RT = 10k, CT = 10pF
Ext. Clock Low Threshold
Pin 1 (CT) = VIN
Ext. Clock High Threshold
Pin 1 (CT) = VIN
Status Indicator Section
Input Voltage Window
@ E/A Inputs, VCM = 1.5V
Saturation Voltage
E/A ∆ Input = 0V, ISINK = 1.6mA
Max. Output Current
Pin 13 = 3V, E/A ∆ Input = 0.0V
Leakage Current
Pin 13 = 40V, E/A ∆Input = 0.2V
Supply Current
VIN = 35V
UVLO Section
Drivers Enabled Threshold
At Input Supply VIN
Status Output Enabled
At Input Supply VIN
Threshold
Change in Reference Output
When VIN Reaches UVLO
Threshold
3
UC1901/UC2901
MIN
TYP MAX
MIN
1.485
1.470
1.47
1.455
1.5
1.5
2
4
–35
1.515
1.530
10
10
–55
1
–1
0.1
60
80
100
0.7
150
–3
1
0.3
4
–3
1
11
±1.6
500
–15
12
±2.8
700
–35
25
13
140
130
150
160
170
.35
40
60
80
0.4
90
–2
.15
5
1.5
1.5
2
4
–35
1.53
1.545
15
15
–55
1
–1
0.1
60
80
100
0.7
150
–3
1
0.3
8
–6
2
mV
µA
µA
dB
dB
dB
V
µA
mA
MHz
V/µS
10
±1.6
500
–15
12
±2.8
700
–35
25
14
dB
V
µA
mA
MHz
130
120
150
170
180
.60
kHz
kHz
%/V
MHz
V
V
40
60
80
0.4
90
–2
0.5
UC3901
UNITS
TYP
MAX
.15
5
0.5
1.6
±135
±150
8
15
.05
5
±165
0.45
1.6
±170
0.45
V
mV
mV
mV
±130
±150
8
1
8
15
.05
5
5
10
mV
V
mA
µA
mA
3.9
3.9
4.5
4.5
3.9
3.9
4.5
4.5
V
V
–2
–30
–2
–30
mV
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
Figure 3. Typical Driver Output Swing vs
Temperature
APPLICATION INFORMATION
The error amplifier compensation terminal, Pin 12, is intended as a source of feedback to the amplifier's inverting input at Pin 11. For most applications, a series DC
blocking capacitor should be part of the feedback network. The amplifier is internally compensated for unity
feedback.
With the internal oscillator the squarewave will have a
fixed 50% duty cycle. If the internal oscillator is disabled
by connecting Pin 1, CR, to VIN then the frequency and
duty cycle of the output will be determined by the input
clock waveform at Pin 2. If the oscillator remains disabled
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 outputs 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 input signal. There is a fixed 12dB of gain from the error
amplifier compensation pin to the modulator driver outputs. The frequency of the output waveform is controlled
by either the internal oscillator or an external clock signal.
The driver outputs are emitter followers which will source
a minimum of 15mA of current. The sink current, internally limited at 700µA, can be increased by adding resistors 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
6
PACKAGE OPTION ADDENDUM
www.ti.com
5-Dec-2011
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package
Drawing
Pins
Package Qty
Eco Plan
(2)
Lead/
Ball Finish
MSL Peak Temp
(3)
(Requires Login)
5962-89441012A
ACTIVE
LCCC
FK
20
1
TBD
Call TI
Call TI
5962-8944101CA
ACTIVE
CDIP
J
14
1
TBD
Call TI
Call TI
5962-8944101VCA
ACTIVE
CDIP
J
14
1
TBD
A42
N / A for Pkg Type
UC1901J
ACTIVE
CDIP
J
14
1
TBD
A42
N / A for Pkg Type
UC1901J883B
ACTIVE
CDIP
J
14
1
TBD
A42
N / A for Pkg Type
UC1901L
ACTIVE
LCCC
FK
20
1
TBD
POST-PLATE N / A for Pkg Type
UC1901L883B
ACTIVE
LCCC
FK
20
1
TBD
POST-PLATE N / A for Pkg Type
UC2901D
ACTIVE
SOIC
D
14
50
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC2901DG4
ACTIVE
SOIC
D
14
50
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC2901DTR
ACTIVE
SOIC
D
14
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC2901DTR/80209
OBSOLETE
SOIC
D
14
UC2901DTR/80209G4
OBSOLETE
SOIC
D
14
UC2901DTRG4
ACTIVE
SOIC
D
14
TBD
TBD
2500
Green (RoHS
& no Sb/Br)
Call TI
Call TI
Call TI
Call TI
CU NIPDAU Level-2-260C-1 YEAR
UC2901J
ACTIVE
CDIP
J
14
1
TBD
UC2901N
ACTIVE
PDIP
N
14
25
Green (RoHS
& no Sb/Br)
CU NIPDAU N / A for Pkg Type
UC2901NG4
ACTIVE
PDIP
N
14
25
Green (RoHS
& no Sb/Br)
CU NIPDAU N / A for Pkg Type
UC2901Q
ACTIVE
PLCC
FN
20
46
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
UC2901QG3
ACTIVE
PLCC
FN
20
46
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
UC3901D
ACTIVE
SOIC
D
14
50
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC3901DG4
ACTIVE
SOIC
D
14
50
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC3901DTR
ACTIVE
SOIC
D
14
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
Addendum-Page 1
A42
Samples
N / A for Pkg Type
PACKAGE OPTION ADDENDUM
www.ti.com
5-Dec-2011
Orderable Device
Status
(1)
Package Type Package
Drawing
Pins
Package Qty
Eco Plan
(2)
Lead/
Ball Finish
MSL Peak Temp
(3)
Samples
(Requires Login)
UC3901DTRG4
ACTIVE
SOIC
D
14
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC3901DW
ACTIVE
SOIC
DW
16
40
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC3901DWG4
ACTIVE
SOIC
DW
16
40
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC3901DWTR
ACTIVE
SOIC
DW
16
2000
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC3901DWTRG4
ACTIVE
SOIC
DW
16
2000
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
UC3901N
ACTIVE
PDIP
N
14
25
Green (RoHS
& no Sb/Br)
CU NIPDAU N / A for Pkg Type
UC3901NG4
ACTIVE
PDIP
N
14
25
Green (RoHS
& no Sb/Br)
CU NIPDAU N / A for Pkg Type
UC3901Q
ACTIVE
PLCC
FN
20
46
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
UC3901QG3
ACTIVE
PLCC
FN
20
46
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
UC3901QTR
ACTIVE
PLCC
FN
20
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
UC3901QTRG3
ACTIVE
PLCC
FN
20
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Addendum-Page 2
PACKAGE OPTION ADDENDUM
www.ti.com
5-Dec-2011
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
OTHER QUALIFIED VERSIONS OF UC1901, UC1901-SP, UC2901, UC3901 :
• Catalog: UC3901, UC1901
• Enhanced Product: UC2901-EP
• Military: UC1901
• Space: UC1901-SP, UC1901-SP
NOTE: Qualified Version Definitions:
• Catalog - TI's standard catalog product
• Enhanced Product - Supports Defense, Aerospace and Medical Applications
• Military - QML certified for Military and Defense Applications
• Space - Radiation tolerant, ceramic packaging and qualified for use in Space-based application
Addendum-Page 3
PACKAGE MATERIALS INFORMATION
www.ti.com
13-Jan-2010
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
UC2901DTR
SOIC
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
D
14
2500
330.0
16.4
6.5
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
9.0
2.1
8.0
16.0
Q1
UC3901DTR
SOIC
D
14
2500
330.0
16.4
6.5
9.0
2.1
8.0
16.0
Q1
UC3901DWTR
SOIC
DW
16
2000
330.0
16.4
10.85
10.8
2.7
12.0
16.0
Q1
UC3901QTR
PLCC
FN
20
1000
330.0
16.4
10.3
10.3
4.9
12.0
16.0
Q1
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
13-Jan-2010
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
UC2901DTR
SOIC
D
14
2500
346.0
346.0
33.0
UC3901DTR
SOIC
D
14
2500
346.0
346.0
33.0
UC3901DWTR
SOIC
DW
16
2000
346.0
346.0
33.0
UC3901QTR
PLCC
FN
20
1000
346.0
346.0
33.0
Pack Materials-Page 2
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