OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

UC3842AN

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18
© Semiconductor Components Industries, LLC, 2005
November, 2005 − Rev. 8
1 Publication Order Number:
UC3842A/D
UC3842A, UC3843A,
UC2842A, UC2843A
High Performance
Current Mode Controllers
The UC3842A, UC3843A series of high performance fixed
frequency current mode controllers are specifically designed for
off−line and DC−to−DC converter applications offering the designer a
cost effective 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, cycle−by−cycle
current limiting, programmable output deadtime, and a latch for single
pulse metering.
These devices are available in an 8−pin dual−in−line plastic package
as well as the 14−pin plastic surface mount (SOIC−14). The SOIC−14
package has separate power and ground pins for the totem pole output
stage.
The UCX842A has UYLO thresholds of 16 V (on) and 10 V (off),
ideally suited for off−line converters. The UCX843A is tailored for
lower voltage applications having UVLO thresholds of 8.5 V (on) and
7.6 V (off).
Features
• Trimmed Oscillator Discharge Current for Precise Duty Cycle
Control
• Current Mode Operation to 500 kHz
• Automatic Feed Forward Compensation
• Latching PWM for Cycle−By−Cycle Current Limiting
• Internally Trimmed Reference with Undervoltage Lockout
• High Current Totem Pole Output
• Undervoltage Lockout with Hysteresis
• Low Startup and Operating Current
• Direct Interface with ON Semiconductor SENSEFET™ Products
• Pb−Free Packages are Available
14
SOIC−14
D SUFFIX
CASE 751A
1
See detailed ordering and shipping information in the package
dimensions section on page 15 of this data sheet.
ORDERING INFORMATION
See general marking information in the device marking
section on page 16 of this data sheet.
DEVICE MARKING INFORMATION
1
8
PDIP−8
N SUFFIX
CASE 626
PIN CONNECTIONS
(Top View)
V
ref
(Top View)
Compensation
Voltage Feedback
Current Sense
R
T
/C
T
V
ref
V
CC
Output
GND
1
2
3
45
6
7
8
Compensation
NC
Voltage Feedback
NC
Current Sense
NC
R
T
/C
T
NC
V
CC
V
C
Output
GND
Power Ground
1
2
3
4
5
6
7
9
8
10
11
12
13
14
1
8
SOIC−8
D1 SUFFIX
CASE 751
http://onsemi.com
UC3842A, UC3843A, UC2842A, UC2843A
http://onsemi.com
2
Figure 1. Simplified Block Diagram
5.0V
Reference
Latching
PWM
V
CC
Undervoltage
Lockout
Oscillator
Error
Amplifier
7(12)
V
C
7(11)
Output
6(10)
Power
Ground
5(8)
3(5)
Current
Sense
Input
V
ref
8(14)
4(7)
2(3)
1(1)
GND 5(9)
R
T
C
T
Voltage
Feedback
Input
R
R
+
−
V
ref
Undervoltage
Lockout
Output
Compensation
Pin numbers in parenthesis are for the D suffix SOIC−14 package.
V
CC
MAXIMUM RATINGS
Rating Symbol Value Unit
Bias and Driver Voltages (Zero Series Impedance, see also Total Device spec) V
CC
, V
C
30 V
Total Power Supply and Zener Current (I
CC
+ I
Z
) 30 mA
Output Current, Source or Sink (Note 1) I
O
1.0 A
Output Energy (Capacitive Load per Cycle) W 5.0
J
Current Sense and Voltage Feedback Inputs V
in
− 0.3 to + 5.5 V
Error Amp Output Sink Current I
O
10 mA
Power Dissipation and Thermal Characteristics
D Suffix, Plastic Package
Maximum Power Dissipation @ T
A
= 25°C
Thermal Resistance, Junction−to−Air
N Suffix, Plastic Package
Maximum Power Dissipation @ T
A
= 25°C
Thermal Resistance, Junction−to−Air
P
D
R
JA
P
D
R
JA
862
145
1.25
100
mW
°C/W
W
°C/W
Operating Junction Temperature T
J
+ 150 °C
Operating Ambient Temperature
UC3842A, UC3843A
UC2842A, UC2843A
T
A
0 to + 70
− 25 to + 85
°C
Storage Temperature Range T
stg
− 65 to + 150 °C
Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit
values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied,
damage may occur and reliability may be affected.
1. Maximum Package power dissipation limits must be observed.
UC3842A, UC3843A, UC2842A, UC2843A
http://onsemi.com
3
ELECTRICAL CHARACTERISTICS (V
CC
= 15 V, [Note 2], R
T
= 10 k, C
T
= 3.3 nF, T
A
= T
low
to T
high
[Note 3],
unless otherwise noted.)
Characteristics Symbol
UC284XA UC384XA
Unit
Min Typ Max Min Typ Max
REFERENCE SECTION
Reference Output Voltage (I
O
= 1.0 mA, T
J
= 25°C) V
ref
4.95 5.0 5.05 4.9 5.0 5.1 V
Line Regulation (V
CC
= 12 V to 25 V) Reg
line
− 2.0 20 − 2.0 20 mV
Load Regulation (I
O
= 1.0 mA to 20 mA) Reg
load
− 3.0 25 − 3.0 25 mV
Temperature Stability T
S
− 0.2 − − 0.2 − mV/°C
Total Output Variation over Line, Load, Temperature V
ref
4.9 − 5.1 4.82 − 5.18 V
Output Noise Voltage (f = 10 Hz to 10 kHz,
T
J
= 25°C)
V
n
− 50 − − 50 −
V
Long Term Stability (T
A
= 125°C for 1000 Hours) S − 5.0 − − 5.0 − mV
Output Short Circuit Current I
SC
− 30 − 85 − 180 − 30 − 85 − 180 mA
OSCILLATOR SECTION
Frequency
T
J
= 25°C
T
A
= T
low
to T
high
f
osc
47
46
52
−
57
60
47
46
52
−
57
60
kHz
Frequency Change with Voltage (V
CC
= 12 V to 25 V)
f
osc/
V
− 0.2 1.0 − 0.2 1.0 %
Frequency Change with Temperature
T
A
= T
low
to T
high
f
osc/
T
− 5.0 − − 5.0 − %
Oscillator Voltage Swing (Peak−to−Peak) V
osc
− 1.6 − − 1.6 − V
Discharge Current (V
osc
= 2.0 V)
T
J
= 25°C
T
A
= T
low
to T
high
I
dischg
7.5
7.2
8.4
−
9.3
9.5
7.5
7.2
8.4
−
9.3
9.5
mA
ERROR AMPLIFIER SECTION
Voltage Feedback Input (V
O
= 2.5 V) V
FB
2.45 2.5 2.55 2.42 2.5 2.58 V
Input Bias Current (V
FB
= 2.7 V) I
IB
− −0.1 −1.0 − −0.1 −2.0
A
Open Loop Voltage Gain (V
O
= 2.0 V to 4.0 V) A
VOL
65 90 − 65 90 − dB
Unity Gain Bandwidth (T
J
= 25°C) BW 0.7 1.0 − 0.7 1.0 − MHz
Power Supply Rejection Ratio (V
CC
= 12 V to 25 V) PSRR 60 70 − 60 70 − dB
Output Current
Sink (V
O
= 1.1 V, V
FB
= 2.7 V)
Source (V
O
= 5.0 V, V
FB
= 2.3 V)
I
Sink
I
Source
2.0
−0.5
12
−1.0
−
−
2.0
−0.5
12
−1.0
−
−
mA
Output Voltage Swing
High State (R
L
= 15 k to ground, V
FB
= 2.3 V)
Low State (R
L
= 15 k to V
ref
, V
FB
= 2.7 V)
V
OH
V
OL
5.0
−
6.2
0.8
−
1.1
5.0
−
6.2
0.8
−
1.1
V
2. Adjust V
CC
above the Startup threshold before setting to 15 V.
3. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
T
low
=0°C for UC3842A, UC3843A T
high
= +70°C for UC3842A, UC3843A
−25°C for UC2842A, UC2843A +85°C for UC2842A, UC2843A
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18

UC3842AN

Mfr. #:
Buy UC3842AN
Manufacturer:
Texas Instruments
Description:
Switching Controllers Current Mode
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet