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  ON Semiconductor Electronic Components Datasheet  

UC2844B Datasheet

High Performance Current Mode Controllers

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UC3844B, UC3845B,
UC2844B, UC2845B
High Performance
Current Mode Controllers
The UC3844B, UC3845B series are high performance fixed frequency
current mode controllers. They are specifically designed for OffLine
and dcdc converter applications offering the designer a costeffective
solution with minimal external components. These integrated circuits
feature an oscillator, a temperature compensated reference, high gain
error amplifier, current sensing comparator, and a high current totem pole
output ideally suited for driving a power MOSFET.
Also included are protective features consisting of input and
reference undervoltage lockouts each with hysteresis, cyclebycycle
current limiting, a latch for single pulse metering, and a flipflop
which blanks the output off every other oscillator cycle, allowing
output deadtimes to be programmed from 50% to 70%.
These devices are available in an 8pin dualinline and surface
mount (SOIC8) plastic package as well as the 14pin plastic surface
mount (SOIC14). The SOIC14 package has separate power and
ground pins for the totem pole output stage.
The UCX844B has UVLO thresholds of 16V (on) and 10V (off), ideally
suited for offline converters. The UCX845B is tailored for lower voltage
applications having UVLO thresholds of 8.5V (on) and 7.6V (off).
Features
Trimmed Oscillator for Precise Frequency Control
Oscillator Frequency Guaranteed at 250 kHz
Current Mode Operation to 500 kHz Output Switching Frequency
Output Deadtime Adjustable from 50% to 70%
Automatic Feed Forward Compensation
Latching PWM for CycleByCycle Current Limiting
Internally Trimmed Reference with Undervoltage Lockout
High Current Totem Pole Output
Undervoltage Lockout with Hysteresis
Low Startup and Operating Current
These Devices are PbFree and are RoHS Compliant
NCV Prefix for Automotive and Other Applications Requiring
Unique Site and Control Change Requirements; AECQ100
Qualified and PPAP Capable
VCC 7(12)
Vref
8(14)
RT/CT
4(7)
Voltage
Feedback
Input
2(3)
Output/
Compensation
1(1)
5.0V
Reference
R
Vref
R Undervoltage
Lockout
Oscillator
Latching
PWM
Error
Amplifier
VCC
Undervoltage
Lockout
GND 5(9)
Pin numbers in parenthesis are for the D suffix SOIC-14 package.
Figure 1. Simplified Block Diagram
VC
7(11)
Output
6(10)
Power
Ground
5(8)
Current
Sense Input
3(5)
© Semiconductor Components Industries, LLC, 2013
August, 2013 Rev. 11
1
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8
1
14
1
8
1
PDIP8
N SUFFIX
CASE 626
SOIC14
D SUFFIX
CASE 751A
SOIC8
D1 SUFFIX
CASE 751
PIN CONNECTIONS
Compensation 1
Voltage Feedback 2
8 Vref
7 VCC
Current Sense 3
6 Output
RT/CT 4
5 GN
D
(Top View)
Compensation 1
NC 2
Voltage Feedback 3
NC 4
Current Sense 5
NC 6
RT/CT 7
14 Vref
13 NC
12 VCC
11 VC
10 Output
9 GND
8 Power Ground
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 15 of this data sheet.
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 16 of this data sheet.
Publication Order Number:
UC3844B/D


  ON Semiconductor Electronic Components Datasheet  

UC2844B Datasheet

High Performance Current Mode Controllers

No Preview Available !

UC3844B, UC3845B, UC2844B, UC2845B
MAXIMUM RATINGS
Rating
Symbol
Value
Unit
Bias and Driver Voltages (Zero Series Impedance, see also Total Device spec) (Note 1)
Total Power Supply and Zener Current
Output Current, Source or Sink (Note 2)
Output Energy (Capacitive Load per Cycle)
VCC, VC
(ICC + IZ)
IO
W
36 V
30 mA
1.0 A
5.0 mJ
Current Sense and Voltage Feedback Inputs
Error Amp Output Sink Current
Power Dissipation and Thermal Characteristics
D Suffix, Plastic Package, SOIC14 Case 751A
Maximum Power Dissipation @ TA = 25°C
Thermal Resistance, JunctiontoAir
D1 Suffix, Plastic Package, SOIC8 Case 751
Maximum Power Dissipation @ TA = 25°C
Thermal Resistance, JunctiontoAir
N Suffix, Plastic Package, Case 626
Maximum Power Dissipation @ TA = 25°C
Thermal Resistance, JunctiontoAir
Operating Junction Temperature
Operating Ambient Temperature
UC3844B, UC3845B
UC2844B, UC2845B
UC3844BV, UC3845BV
Vin
IO
PD
RqJA
PD
RqJA
PD
RqJA
TJ
TA
0.3 to + 5.5
10
V
mA
862
145
702
178
1.25
100
+150
0 to +70
25 to +85
40 to +105
mW
°C/W
mW
°C/W
W
°C/W
°C
°C
Storage Temperature Range
Tstg
65 to +150
°C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. The voltage is clamped by a zener diode (see page 9 Under Voltage Lockout section). Therefore this voltage may be exceeded as long as
the total power supply and zener current is not exceeded.
2. Maximum package power dissipation limits must be observed.
3. This device series contains ESD protection and exceeds the following tests: Human Body Model 4000 V per JEDEC Standard
JESD22-A114B, Machine Model Method 200 V per JEDEC Standard JESD22-A115-A
4. This device contains latch-up protection and exceeds 100 mA per JEDEC Standard JESD78
ELECTRICAL CHARACTERISTICS (VCC = 15 V [Note 5], RT = 10 k, CT = 3.3 nF. For typical values TA = 25°C, for min/max values
TA is the operating ambient temperature range that applies [Note 6], unless otherwise noted.)
UC284xB
UC384xB, xBV, NCV384xBV
Characteristic
Symbol Min Typ Max
Min
Typ
Max Unit
REFERENCE SECTION
Reference Output Voltage (IO = 1.0 mA, TJ = 25°C)
Vref
4.95 5.0 5.05
4.9
5.0
5.1
Line Regulation (VCC = 12 V to 25 V)
Regline 2.0 20
2.0 20
Load Regulation (IO = 1.0 mA to 20 mA)
Regload 3.0 25
3.0 25
Temperature Stability
TS 0.2 − − 0.2
Total Output Variation over Line, Load, & Temperature
Vref
4.9 5.1 4.82
5.18
Output Noise Voltage (f = 10 Hz to 10 kHz, TJ = 25°C)
Vn
50
50
Long Term Stability (TA = 125°C for 1000 Hours)
S 5.0 − − 5.0
Output Short Circuit Current
ISC 30 85 180 30 85 180
OSCILLATOR SECTION
Frequency
TJ = 25°C
TA = Tlow to Thigh
TJ = 25°C (RT = 6.2 k, CT = 1.0 nF)
fOSC
49 52 55
49
52
55
48 56
48
56
225 250 275
225
250
275
Frequency Change with Voltage (VCC = 12 V to 25 V) DfOSC/DV
0.2 1.0
0.2 1.0
Frequency Change w/ Temperature (TA = Tlow to Thigh) DfOSC/DT
1.0
0.5
Oscillator Voltage Swing (PeaktoPeak)
VOSC
1.6
1.6
5. Adjust VCC above the Startup threshold before setting to 15 V.
6. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
Tlow = 0°C for UC3844B, UC3845B
= 25°C for UC2844B, UC2845B
Thigh = + 70°C for UC3844B, UC3845B
= + 85°C for UC2844B, UC2845B
= 40°C for UC384xBV, NCV384xBV
=+105°C for UC3844BV, UC3845BV
= +125°C for NCV384xBV
V
mV
mV
mV/°C
V
mV
mV
mA
kHz
%
%
V
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Part Number UC2844B
Description High Performance Current Mode Controllers
Maker ON Semiconductor
Total Page 19 Pages
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