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UC3843B Datasheet

(UC3842B / UC3843B) HIGH PERFORMANCE CURRENT MODE CONTROLLERS


UC3843B Datasheet Preview


UC3842B, UC3843B,
UC2842B, UC2843B
High Performance
Current Mode Controllers
The UC3842B, UC3843B 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 a trimmed oscillator for precise duty cycle
control, 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, programmable output deadtime, and a latch for single
pulse metering.
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 UCX842B has UVLO thresholds of 16 V (on) and 10 V (off),
ideally suited for offline converters. The UCX843B is tailored for
lower voltage applications having UVLO thresholds of 8.5 V (on) and
7.6 V (off).
Features
Trimmed Oscillator for Precise Frequency Control
Oscillator Frequency Guaranteed at 250 kHz
Current Mode Operation to 500 kHz
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
This is a PbFree and HalideFree Device
VCC 7(12)
Vref
8(14)
R
5.0V
Reference
VCC
Undervoltage
Lockout
Vref
R Undervoltage
Lockout
VC
7(11)
RT/CT
Oscillator
Output
4(7)
Voltage
Feedback
+
Latching
PWM
6(10)
Power
Ground
Input -
5(8)
2(3)
Output
Compensation
1(1)
Error
Amplifier
GND 5(9)
Current
Sense
3(5) Input
Pin numbers in parenthesis are for the D suffix SOIC14 package.
Figure 1. Simplified Block Diagram
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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
Current Sense 3
RT/CT 4
8 Vref
7 VCC
6 Output
5 GND
(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 17 of this data sheet.
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 19 of this data sheet.
© Semiconductor Components Industries, LLC, 2013
September, 2013 Rev. 17
1
Publication Order Number:
UC3842B/D
Page 1

UC3842B, UC3843B, UC2842B, UC2843B
MAXIMUM RATINGS
Rating
Bias and Driver Voltages (Zero Series Impedance, see also Total Device spec)
Total Power Supply and Zener Current
Output Current, Source or Sink
Output Energy (Capacitive Load per Cycle)
Symbol
VCC, VC
(ICC + IZ)
IO
W
Value
30
30
1.0
5.0
Unit
V
mA
A
mJ
Current Sense, Voltage Feedback, Vref and Rt/Ct Inputs
Compensation
Output
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
UC3842B, UC3843B
UC2842B, UC2843B
UC2843D
UC3842BV, UC3843BV
Vin
Vcomp
Vo
IO
PD
RqJA
PD
RqJA
PD
RqJA
TJ
TA
0.3 to + 5.5
0.3 to + 7.2
0.3 to VCC or
VC + 0.3
10
V
V
V
mA
862
145
702
178
1.25
100
+150
0 to 70
25 to + 85
40 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. 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
2. This device contains latch-up protection and exceeds 100 mA per JEDEC Standard JESD78
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Page 2

UC3842B, UC3843B, UC2842B, UC2843B
ELECTRICAL CHARACTERISTICS (VCC = 15 V [Note 3], 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 4], unless otherwise noted.)
UC284XB, UC2843D
UC384XB, XBV
Characteristics
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 V
Line Regulation (VCC = 12 V to 25 V)
Regline
2.0 20
2.0 20
mV
Load Regulation (IO = 1.0 mA to 20 mA)
Regload
3.0 25
3.0 25
mV
Temperature Stability
TS
0.2
0.2 mV/°C
Total Output Variation over Line, Load, and Temperature
UC284XB
UC2843D
Vref
V
4.9 5.1 4.82 5.18
4.82 5.18
Output Noise Voltage (f = 10 Hz to 10 kHz, TJ = 25°C)
Long Term Stability (TA = 125°C for 1000 Hours)
Output Short Circuit Current
OSCILLATOR SECTION
Frequency
TJ = 25°C
TA = Tlow to Thigh
TJ = 25°C (RT = 6.2 k, CT = 1.0 nF)
Frequency Change with Voltage (VCC = 12 V to 25 V)
Frequency Change with Temperature, TA = Tlow to Thigh
Oscillator Voltage Swing (PeaktoPeak)
Discharge Current (VOSC = 2.0 V)
TJ = 25°C, TA = Tlow to Thigh
UC284XB, UC384XB
UC2843D, UC384XBV
Vn
S
ISC
fOSC
DfOSC/DV
DfOSC/DT
VOSC
Idischg
30
49
48
225
7.8
7.5
50
5.0
85 180 30
52 55 49
56 48
250 275 225
0.2 1.0
1.0
1.6
8.3 8.8 7.8
8.8 7.6
− − 7.2
50
5.0
85 180
52 55
56
250 275
0.2 1.0
0.5
1.6
8.3 8.8
8.8
8.8
mV
mV
mA
kHz
%
%
V
mA
ERROR AMPLIFIER SECTION
Voltage Feedback Input (VO = 2.5 V)
UC284XB
UC2843D
VFB
2.45 2.5 2.55 2.42 2.5 2.58
2.42 2.5 2.58
V
Input Bias Current (VFB = 5.0 V)
Open Loop Voltage Gain (VO = 2.0 V to 4.0 V)
Unity Gain Bandwidth (TJ = 25°C)
Power Supply Rejection Ratio (VCC = 12 V to 25 V)
Output Current
Sink (VO = 1.1 V, VFB = 2.7 V)
Source (VO = 5.0 V, VFB = 2.3 V)
Output Voltage Swing
High State (RL = 15 k to ground, VFB = 2.3 V)
Low State (RL = 15 k to Vref, VFB = 2.7 V)
UC284XB, UC384XB
UC2843D, UC384XBV
IIB
AVOL
BW
PSRR
ISink
ISource
VOH
VOL
− − 0.1 1.0 − − 0.1 2.0
65 90 65 90
0.7 1.0 0.7 1.0
60 70 60 70
2.0 12 2.0 12
0.5 1.0 − − 0.5 1.0
5.0 6.2 5.0 6.2
0.8 1.1 0.8 1.1
− − − − 0.8 1.2
mA
dB
MHz
dB
mA
V
3. Adjust VCC above the Startup threshold before setting to 15 V.
4. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
TTlhoigwh==0+°7C0f°oCr
UC3842B, UC3843B; 25°C for
for UC3842B, UC3843B; +85°C
UC2842B, UC2843B; 40°C for UC3842BV,
for UC2842B, UC2843B, UC2843D; +105°C
UC3843BV, UC2843D
for UC3842BV, UC3843BV
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Page 3

UC3842B, UC3843B, UC2842B, UC2843B
ELECTRICAL CHARACTERISTICS (VCC = 15 V [Note 7], 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 8], unless otherwise noted.)
UC284XB, UC2843D
UC384XB, XBV
Characteristics
Symbol Min Typ Max Min Typ Max Unit
CURRENT SENSE SECTION
Current Sense Input Voltage Gain (Notes 5 and 6)
UC2843D, UC284XB, UC384XB
UC384XBV
AV
V/V
2.85 3.0 3.15 2.85 3.0 3.15
− − − 2.85 3.0 3.25
Maximum Current Sense Input Threshold (Note 5)
UC2843D, UC284XB, UC384XB
UC384XBV
Vth
0.9 1.0 1.1 0.9 1.0 1.1
− − − 0.85 1.0 1.1
V
Power Supply Rejection Ratio (VCC = 12 V to 25 V, Note 5)
Input Bias Current
Propagation Delay (Current Sense Input to Output)
OUTPUT SECTION
Output Voltage
Low State (ISink = 20 mA)
(ISink = 200 mA)
High State (ISource = 20 mA)
(ISource = 200 mA)
UC284XB, UC384XB
UC384XBV, UC2843D
UC284XB, UC384XB
UC384XBV, UC2843D
Output Voltage with UVLO Activated (VCC = 6.0 V, ISink = 1.0 mA)
Output Voltage Rise Time (CL = 1.0 nF, TJ = 25°C)
Output Voltage Fall Time (CL = 1.0 nF, TJ = 25°C)
UNDERVOLTAGE LOCKOUT SECTION
Startup Threshold (VCC)
UCX842B, BV
UCX843B, BV, D
PSRR
IIB
tPLH(In/Out)
VOL
VOH
VOL(UVLO)
tr
tf
Vth
13
12
15
7.8
70
2.0
150
10
300
0.1 0.4
1.6 2.2
−−
13.5
−−
13.4
0.1 1.1
50 150
50 150
16 17
8.4 9.0
70
− − 2.0 10
150 300
0.1
1.6
1.6
13 13.5
12.9 13.5
12 13.4
0.4
2.2
2.3
0.1 1.1
50 150
50 150
14.5 16 17.5
7.8 8.4 9.0
dB
mA
ns
V
V
ns
ns
V
Minimum Operating Voltage After TurnOn (VCC)
VCC(min)
V
UCX842B, BV
9.0 10 11 8.5 10 11.5
UCX843B, BV, D
7.0 7.6 8.2 7.0 7.6 8.2
PWM SECTION
Duty Cycle
Maximum UC284XB, UC384XB, UC2843D
Maximum UC384XBV
Minimum
%
DC(max) 94 96 94 96
− − − 93 96
DC(min)
0
0
TOTAL DEVICE
Power Supply Current
Startup (VCC = 6.5 V for UCX843B, UC2843D
Startup VCC 14 V for UCX842B, BV)
(Note 7)
ICC + IC
mA
0.3 0.5 0.3 0.5
12 17 12 17
Power Supply Zener Voltage (ICC = 25 mA)
VZ 30 36 30 36
5. This parameter is measured at the latch trip point with VFB = 0 V.
6. Comparator gain is defined as: AV
DV Output Compensation
DV Current Sense Input
7. Adjust VCC above the Startup threshold before setting to 15 V.
8. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
Tlow = 0°C for UC3842B, UC3843B; 25°C for UC2842B, UC2843B; 40°C for UC3842BV, UC3843BV, UC2843D
Thigh = +70°C for UC3842B, UC3843B; +85°C for UC2842B, UC2843B, UC2843D; +105°C for UC3842BV, UC3843BV
V
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4
Page 4
Part Number UC3843B
Manufactur ON Semiconductor
Description (UC3842B / UC3843B) HIGH PERFORMANCE CURRENT MODE CONTROLLERS
Total Page 22 Pages
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