UC3527B
Not Recommended For New Designs
application
INFO
available
UC1525B UC1527B
UC2525B UC2527B
UC3525B UC3527B
Regulating Pulse Width Modulators
FEATURES
DESCRIPTION
• 8 to 35V Operation
The UC1525B/1527B series of pulse width modulator integrated circuits
are designed to offer improved performance and lowered external parts
count when used in designing all types of switching power supplies. The
on-chip +5.1V buried zener reference is trimmed to ±0.75% and the input
common-mode range of the error amplifier includes the reference voltage,
eliminating external resistors. A sync input to the oscillator allows multiple
units to be slaved or a single unit to be synchronized to an external system
clock. A single resistor between the CT and the discharge terminals provide
a wide range of dead time adjustment. These devices also feature built-in
soft-start circuitry with only an external timing capacitor required. A shutdown terminal controls both the soft-start circuitry and the output stages,
providing instantaneous turn off through the PWM latch with pulsed shutdown, as well as soft-start recycle with longer shutdown commands. These
functions are also controlled by an undervoltage lockout which keeps the
outputs off and the soft-start capacitor discharged for sub-normal input voltages. This lockout circuitry includes approximately 500mV of hysteresis for
jitter-free operation. Another feature of these PWM circuits is a latch following the comparator. Once a PWM pulse has been terminated for any reason, the outputs will remain off for the duration of the period. The latch is
reset with each clock pulse. The output stages are totem-pole designs capable of sourcing or sinking in excess of 200mA. The UC1525B output
stage features NOR logic, giving a LOW output for an OFF state. The
UC1527B utilizes OR logic which results in a HIGH output level when OFF.
• 5.1V Buried Zener Reference
Trimmed to ±0.75%
• 100Hz to 500kHz Oscillator Range
• Separate Oscillator Sync Terminal
• Adjustable Deadtime Control
• Internal Soft-Start
• Pulse-by-Pulse Shutdown
• Input Undervoltage Lockout with
Hysteresis
• Latching PWM to Prevent Multiple
Pulses
• Dual Source/Sink Output Drivers
• Low Cross Conduction Output Stage
• Tighter Reference Specifications
BLOCK DIAGRAM
UDG-95055
SLUS376 JULY 1995
UC3527B
Not Recommended For New Designs
UC1525B UC1527B
UC2525B UC2527B
UC3525B UC3527B
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED OPERATING CONDITIONS
(Note 1)
Supply Voltage, (+VIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . +40V
Collector Supply Voltage (VC). . . . . . . . . . . . . . . . . . . . . . +40V
Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to +5.5V
Analog Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to VIN
Output Current, Source or Sink . . . . . . . . . . . . . . . . . . . 500mA
Reference Output Current . . . . . . . . . . . . . . . . . . . . . . . . 50mA
Oscillator Charging Current . . . . . . . . . . . . . . . . . . . . . . . . 5mA
Power Dissipation at TA = +25°C. . . . . . . . . . . . . . . . . 1000mW
Power Dissipation at TC = +25°C . . . . . . . . . . . . . . . . 2000mW
Operating Junction Temperature . . . . . . . . . . –55°C to +150°C
Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
Input Voltage (+VIN) . . . . . . . . . . . . . . . . . . . . . . . +8V to +35V
Collector Supply Voltage (VC) . . . . . . . . . . . . . . +4.5V to +35V
Sink/Source Load Current (steady state) . . . . . . . . 0 to 100mA
Sink/Source Load Current (peak) . . . . . . . . . . . . . . 0 to 400mA
Reference Load Current . . . . . . . . . . . . . . . . . . . . . . 0 to 20mA
Oscillator Frequency Range. . . . . . . . . . . . . . 100Hz to 400kHz
Oscillator Timing Resistor . . . . . . . . . . . . . . . . . . 2kΩ to 150kΩ
Oscillator Timing Capacitor . . . . . . . . . . . . . . 0.001µF to 0.1µF
Dead Time Resistor Range . . . . . . . . . . . . . . . . . . . 0Ω to 500Ω
Note 1: Range over which the device is functional and parameter limits are guaranteed.
All currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages.
CONNECTION DIAGRAMS
DIL-16, SOIC-16 (Top View)
J or N, DW Packages
LCC-20, PLCC-20 (Top View)
L, Q Packages
ELECTRICAL CHARACTERISTICS:Unless otherwise stated, these specifications apply for TA = –55°C to +125°C for the
UC1525B and UC1527B; –40°C to +85°C for the UC2525B and UC2527B; 0°C to +70°C for the UC3525B and UC3527B; +VIN =
20V, TA = TJ.
UC1525B/UC2525B
UC1527B/UC2527B
PARAMETER
TEST CONDITIONS
UC3525B
UC3527B
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
5.062
5.10
5.138
5.036
5.10
5.164
V
Reference Section
Output Voltage
TJ = 25°C
Line Regulation
VIN = 8V to 35V
5
10
5
10
mV
Load Regulation
IL = 0mA to 20mA
7
15
7
15
mV
50
mV
Temperature Stability (Note 2)
Over Operating Range
Total Output Variation
Line, Load, and Temperature
Short Circuit Current
VREF = 0, TJ =25°C
80
100
Output Noise Voltage (Note 2)
10Hz ≤ f ≤10kHz, TJ = 25°C
40
Long Term Stability (Note 2)
TJ = 125°C, 1000 Hrs.
3
2
10
5.036
50
5.164
10
5.024
5.176
V
80
100
mA
200
40
200
µVrms
10
3
10
mV
UC3527B
Not Recommended For New Designs
UC1525B UC1527B
UC2525B UC2527B
UC3525B UC3527B
ELECTRICAL CHARACTERISTICS:Unless otherwise stated, these specifications apply for TA = –55°C to +125°C for the
UC1525B and UC1527B; –40°C to +85°C for the UC2525B and UC2527B; 0°C to +70°C for the UC3525B and UC3527B; +VIN =
20V, TA = TJ.
UC1525B/UC2525B
UC1527B/UC2527B
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
±2
UC3525B
UC3527B
MIN
TYP
MAX
UNITS
±6
±2
±6
%
±0.3
±1
±1
±2
%
±3
±6
±3
±6
%
120
Hz
Oscillator Section (Note 3)
Initial Accuracy (Notes 2 & 3)
TJ = 25°C
Voltage Stability (Notes 2 & 3)
VIN = 8V to 35V
Temperature Stability (Note 2)
Over Operating Range
Minimum Frequency
RT = 200kW, CT = 0.1mF
120
Maximum Frequency
RT = 2kW, CT = 470pF
400
Current Mirror
IRT = 2mA
1.7
2.0
3.0
3.5
0.3
0.5
1.0
1.2
2.0
2.8
1.0
Clock Amplitude (Notes 2 & 3)
Clock Width (Notes 2 & 3)
TJ = 25°C
Sync Threshold
Sync Input Current
Sync Voltage = 3.5V
400
2.2
kHz
1.7
2.0
2.2
mA
3.0
3.5
0.3
0.5
1.0
ms
1.2
2.0
2.8
V
2.5
1.0
2.5
mA
0.5
5
2
10
mV
1
10
1
10
mA
1
mA
V
Error Amplifier Section (VCM = 5.1V)
Input Offset Voltage
Input Bias Current
Input Offset Current
1
DC Open Loop Gain
RL ³ 10 MegW
60
75
60
75
dB
Gain-Bandwidth Product (Note 2)
AV = 0dB, TJ = 25°C
1
2
1
2
MHz
Output Low Level
0.2
Output High Level
3.8
5.6
0.5
0.2
3.8
0.5
5.6
V
V
Common Mode Rejection
VCM = 1.5V to 5.2V
60
75
60
75
dB
Supply Voltage Rejection
VIN = 8V to 35V
50
60
50
60
dB
45
49
45
49
0.7
0.9
0.7
0.9
PWM Comparator
Minimum Duty Cycle
0
Maximum Duty Cycle (Note 3)
Input Threshold (Note 3)
Zero Duty Cycle
Input Threshold (Note 3)
Maximum Duty Cycle
Input Bias Current (Note 2)
0
%
%
V
3.3
3.6
3.3
3.6
V
0.05
1.0
0.05
1.0
mA
50
80
50
80
mA
0.4
0.7
0.4
0.7
V
0.8
1.0
0.8
1.0
V
Shutdown Section
Soft Start Current
VSHUTDOWN = 0V, VSOFTSTART
= 0V
Soft Start Low Level
VSHUTDOWN = 2.5V
Shutdown Threshold
To outputs, VSOFTSTART =
5.1V, TJ =25°C
25
0.6
25
0.6
Shutdown Input Current
VSHUTDOWN = 2.5V
0.4
1.0
0.4
1.0
mA
Shutdown Delay (Note 2)
VSHUTDOWN = 2.5V, TJ = 25°C
0.2
0.5
0.2
0.5
ms
0.2
0.4
0.2
0.4
V
1.0
2.0
1.0
2.0
Output Drivers (Each Output) (Vc = 20V)
Output Low Level
ISINK = 20mA
ISINK = 100mA
V
ISOURCE = 20mA
18
19
18
19
V
ISOURCE = 100mA
17
18
17
18
V
Undervoltage Lockout
VCOMP and VSOFTSTART =
High
6
7
6
7
Collector Leakage
VC = 35V
Output HIgh Level
8
200
3
8
V
200
mA
UC3527B
Not Recommended For New Designs
UC1525B UC1527B
UC2525B UC2527B
UC3525B UC3527B
ELECTRICAL CHARACTERISTICS:Unless otherwise stated, these specifications apply for TA = –55°C to +125°C for the
UC1525B and UC1527B; –40°C to +85°C for the UC2525B and UC2527B; 0°C to +70°C for the UC3525B and UC3527B; +VIN =
20V, TA = TJ.
UC1525B/UC2525B
UC1527B/UC2527B
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UC3525B
UC3527B
MIN
TYP
MAX
UNITS
Output Drivers (Each Output) (VC = 20V) (cont.)
Rise Time (Note 2)
CL = 1nF, TJ = 25°C
100
600
100
600
ns
Fall Time (Note 2)
CL = 1nF, TJ = 25°C
50
300
50
300
ns
Cross conduction charge
Per cycle, TJ = 25°C
30
VIN = 35V
14
30
nc
Total Standby Current
Supply Current
20
14
20
mA
Note 2: Ensured by design. Not 100% tested in production.
Note 3: Tested at fosc= 40kHz (RT = 3.6KW, CT = 0.01mF, RD = 0W). Approximate oscillator frequency is defined by:
f =
1
C T • (0.7 • RT + 3RD )
PRINCIPLES OF OPERATION AND TYPICAL CHARACTERISTICS
UC1525B Output Saturation Characteristics
UC1525B Output Circuit (1/2 Circuit Shown)
UDG-95056
UDG-95057
UDG-95058
In conventional push-pull bipolar designs, forward base
drive is controlled by R1-R3. Rapid turn-off times for the
power devices are achieved with speed-up capacitors C,
and C2.
UDG-95059
For single-ended supplies, the driver outputs are
grounded. The VC terminal is switched to ground by the totem-pole source transistors on alternate oscillator cycles.
4
UC3527B
Not Recommended For New Designs
UC1525B UC1527B
UC2525B UC2527B
UC3525B UC3527B
UDG-95060
UDG-95061
The low source impedance of the output drivers provides
rapid charging of power FET input capacitance while minimizing external components.
Low power transformers can be driven directly by the
UC1525B. Automatic reset occurs during dead time, when
both ends of the primary winding are switched to ground.
PRINCIPLES OF OPERATION AND TYPICAL
CHARACTERISTICS
plying a positive signal on Pin 10 performs two functions:
the PWM latch is immediately set providing the fastest
turn-off signal to the external soft-start capacitor. If the
shutdown command is short, the PWM signal is terminated without significant discharge of the soft-start capacitor, thus, allowing, for example, a convenient
implementation of pulse-by-pulse current limiting.
Holding Pin 10 high for a longer duration, however, will
ultimately discharge this external capacitor, recycling
slow turn-on upon release.
Shutdown Options (See Block Diagram)
Since both the compensation and soft-start terminals
(Pins 9 and 8) have current source pull-ups, either can
readily accept a pull-down signal which only has to sink a
maximum of 100µA to turn off the outputs. This is subject
to the added requirement of discharging whatever external capacitance may be attached to these pins.
An alternate approach is the use of the shutdown circuitry of Pin 10 which has been improved to enhance the
available shutdown options. Activating this circuit by ap-
UC1525B Oscillator Schematic
UDG-95062
5
UC3527B
Not Recommended For New Designs
UC1525B UC1527B
UC2525B UC2527B
UC3525B UC3527B
Oscillator Charge Time vs. TRand CT
Oscillator Discharge Time vs.DRand CT
UDG-95064
UDG-95063
UC1525B Error Amplifier
Error Amplifier Open-Loop Frequency Response
UDG-95065
UDG-95066
6
UC3527B
Not Recommended For New Designs
UC1525B UC1527B
UC2525B UC2527B
UC3525B UC3527B
LAB TEST FIXTURE
UDG-95067
7
PACKAGE OPTION ADDENDUM
www.ti.com
14-Oct-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
5962-8951105EA
ACTIVE
CDIP
J
16
1
Non-RoHS
& Green
SNPB
N / A for Pkg Type
-55 to 125
5962-8951105EA
UC1525BJ/883B
Samples
UC1525BJ
ACTIVE
CDIP
J
16
1
Non-RoHS
& Green
SNPB
N / A for Pkg Type
-55 to 125
UC1525BJ
Samples
UC1525BJ883B
ACTIVE
CDIP
J
16
1
Non-RoHS
& Green
SNPB
N / A for Pkg Type
-55 to 125
5962-8951105EA
UC1525BJ/883B
Samples
UC2525BDWTR
ACTIVE
SOIC
DW
16
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
UC2525BDW
Samples
UC3525BDW
ACTIVE
SOIC
DW
16
40
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
0 to 70
UC3525BDW
Samples
UC3525BDWTR
ACTIVE
SOIC
DW
16
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
0 to 70
UC3525BDW
Samples
UC3525BN
ACTIVE
PDIP
N
16
25
RoHS & Green
NIPDAU
N / A for Pkg Type
0 to 70
UC3525BN
Samples
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of