UC184xA / 284xA / 384xA
C
URRENT
M
ODE
PWM C
ONTROLLER
T
H E
I
N F I N I T E
P
O W E R
O F
I
N N O V A T I O N
P
R O D U C T I O N
D
A T A
S
H E E T
DESCRIPTION
The UC184xA family of control ICs provides externally programmable oscillator to set
all the necessary features to implement off-line frequency and maximum duty cycle. The
fixed-frequency, current-mode switching power undervoltage lock-out is designed to operate with
supplies with a minimum of external 250µA typ. start-up current, allowing an efficient
components. The current mode architecture bootstrap supply voltage design. Available
demonstrates improved load regulation, pulse- options for this family of products, such as start-
by-pulse current limiting and inherent protection up voltage hysteresis and duty cycle, are
of the power supply output switch. The IC summarized below in the Available Options
includes: A bandgap reference trimmed to ±1% section. The UC184xA family of control ICs is
accuracy, an error amplifier, a current sense also available in 14-pin SOIC package which
comparator with internal clamp to 1V, a high makes the Power Output Stage Collector and
current totem pole output stage for fast Ground pins available.
switching of power MOSFET's, and an
IMPORTANT:
For the most current data, consult
MICROSEMI’s
website:
http://www.microsemi.com
KEY FEATURES
LOW START-UP CURRENT.
(0.5mA max.)
TRIMMED OSCILLATOR
DISCHARGE CURRENT. (See
Product Highlight)
OPTIMIZED FOR OFF-LINE
AND DC-TO-DC
CONVERTERS.
AUTOMATIC FEED FORWARD
COMPENSATION.
PULSE-BY-PULSE CURRENT
LIMITING.
ENHANCED LOAD RESPONSE
CHARACTERISTICS.
UNDER-VOLTAGE LOCKOUT
WITH HYSTERESIS.
DOUBLE PULSE
SUPPRESSION.
HIGH-CURRENT TOTEM POLE
OUTPUT.
INTERNALLY TRIMMED
BANDGAP REFERENCE.
500KHz OPERATION.
LOW RO ERROR AMPLIFIER.
PRODUCT HIGHLIGHT
C
OMPARISON OF
UC384
X
A
SG384x
Min. Limit
VS
.
SG384
X
D
ISCHARGE
C
URRENT
SG384x
Max. Limit
UC384xA
T
A
=25 C
KEY FEATURES
ECONOMICAL OFF-LINE
FLYBACK OR FORWARD
CONVERTERS.
DC-DC BUCK OR BOOST
CONVERTERS.
LOW COST DC MOTOR
CONTROL.
7.5
7.8
-3 s
8.3
Mean
8.8
9.3
+3s
Available Options
Part#
UCx842A
UCx843A
UCx844A
UCx845A
Start-Up
Voltage
16V
8.4V
16V
8.4A
Hysteresis
6V
0.8V
6V
0.8V
Max. Duty
Cycle
<100%
<100%
<50%
<50%
Discharge Cu
rrent Dist ribution - mA
PACKAGE ORDER INFO
T
A
(°C)
0 to 70
-40 to +85
-55 to 125
M
Plastic DIP
8-Pin
DM
Plastic SOIC
8-Pin
D
Plastic SOIC
14-Pin
Y
Ceramic DIP
8-Pin
RoHS Compliant / Pb-free
Transition DC: 0503
RoHS Compliant / Pb-free Transition DC: 0440
UC384xAM
UC284xAM
-
UC384xADM
UC284xADm
-
UC384xAD
UC284xAD
-
-
UC284xAY
UC184xAY
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. UC3842ADM-TR)
Copyright
©
1995
Rev. 1.2a,2005-03-09
L
IN
F
INITY
M
ICROELECTRONICS
I
NC
.
11861 W
ESTERN
A
VENUE
, G
ARDEN
G
ROVE
, CA. 92841, 714-898-8121, F
AX
: 714-893-2570
1
PRODUCT DATABOOK 1996/1997
UC184xA/284xA/384xA
C
URRENT
M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
A B S O L U T E M A X I M U M R AT I N G S
(Note 1)
PACKAGE PIN OUTS
COMP
V
FB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
Supply Voltage (Low Impedance Source) (V
CC
) ......................................................... 30V
Supply Voltage (I
CC
< 30mA) .......................................................................... Self Limiting
Output Current ............................................................................................................. ±1A
Output Energy (Capacitive Load) ................................................................................. 5µJ
Analog Inputs (V
FB
& I
SENSE
) ........................................................................ -0.3V to +6.3V
Error Amp Output Sink Current ............................................................................... 10mA
Power Dissipation at T
A
= 25°C (M Package) .............................................................. 1W
Storage Temperature Range .................................................................... -65°C to +150°C
Lead Temperature (Soldering, 10 Seconds) ............................................................. 300°C
Peak Package Solder Reflow Temp. (40 second max. exposure)..........................................260°C (+0, -5)
Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect
to Ground. Currents are positive into, negative out of the specified terminal. Pin
numbers refer to DIL packages only.
V
REF
V
CC
OUTPUT
GND
M & Y PACKAGE
(Top View)
COMP
V
FB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
V
REF
V
CC
OUTPUT
GND
T H ER MAL DATA
M PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
DM PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
D PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
Y PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
130°C/W
120°C/W
165°C/W
95°C/W
COMP
N.C.
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
DM PACKAGE
(Top View)
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V
REF
N.C.
V
CC
V
C
OUTPUT
GND
PWR GND
D PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
The
θ
JA
numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow
2
Copyright © 1995
Rev. 1.2a 10/25
PRODUCT DATABOOK 1996/1997
UC184xA/284xA/384xA
C
URRENT
M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for UC384xA with 0°C
≤
T
A
≤
70°C, UC284xA with -40°C
≤
T
A
≤
85°C,
UC184xA with -55°C
≤
T
A
≤
125°C; V
CC
=15V; R
T
=10K; C
T
=3.3nF. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal
to the ambient temperature.)
Parameter
Reference Section
Output Voltage
Line Regulation
Load Regulation
Temperature Stability (Note 2 & 7)
Total Output Variation
Output Noise Voltage (Note 2)
Long Term Stability (Note 2)
Output Short Circuit Current
Symbol
Test Conditions
UC184xA/284xA
UC384xA
Units
Min. Typ. Max. Min. Typ. Max.
4.95 5.00 5.05 4.90 5.00 5.10
6
20
6
20
6
25
6
25
0.2 0.4
0.2 0.4
4.9
5.1 4.82
5.18
50
50
5
25
5
25
-30 -100 -180 -30 -100 -180
47
52
0.2
5
1.7
8.3
57
1
47
52
0.2
5
1.7
8.3
57
1
V
mV
mV
mV/°C
V
µV
mV
mA
kHz
%
%
V
mA
mA
V
µA
dB
MHz
dB
mA
mA
V
V
V/V
V
dB
µA
ns
V
V
V
V
ns
ns
V
V
REF
T
J
= 25°C, I
L
= 1mA
12
≤
V
IN
≤
25V
1
≤
I
O
≤
20mA
Over Line, Load, and Temperature
10Hz
≤
f
≤
10kHz, T
J
= 25°C
T
A
= 125°C, t = 1000hrs
V
N
I
SC
Oscillator Section
Initial Accuracy (Note 6)
Voltage Stability
Temperature Stability (Note 2)
Amplitude (Note 2)
Discharge Current
T
J
= 25°C
12
≤
V
CC
≤
25V
T
MIN
≤
T
A
≤
T
MAX
T
J
= 25°C, V
PIN 4
= 2V
V
PIN 4
= 2V, T
MIN
≤
T
A
≤
T
MAX
V
PIN 1
= 2.5V
I
B
A
VOL
UGBW
PSRR
I
OL
I
OH
V
OH
V
OL
A
VOL
PSRR
I
B
T
pd
V
PIN 1
= 5V
12
≤
V
CC
≤
25V
V
PIN 3
= 0 to 2V
I
SINK
= 20mA
I
SINK
= 200mA
I
SOURCE
= 20mA
I
SOURCE
= 200mA
T
J
= 25°C, C
L
= 1nF
T
J
= 25°C, C
L
= 1nF
V
CC
= 5V, I
SINK
= 10mA
2
≤
V
O
≤
4V
T
j
= 25°C
12
≤
V
CC
≤
25V
V
PIN 2
= 2.7V, V
PIN 1
= 1.1V
V
PIN 2
= 2.3V, V
PIN 1
= 5V
V
PIN 2
= 2.3V, R
L
= 15K to ground
V
PIN 2
= 2.7V, R
L
= 15K to V
REF
7.8
7.5
8.8
8.8
7.8
7.6
8.8
8.8
Error Amp Section
Input Voltage
Input Bias Current
Open Loop Gain
Unity Gain Bandwidth (Note 2)
Power Supply Rejection Ratio (Note 3)
Output Sink Current
Output Source Current
Output Voltage High Level
Output Voltage Low Level
2.45 2.50 2.55 2.42 2.50 2.58
-0.3
-1
-0.3
-2
65
90
65
90
0.7
1
0.7
1
60
70
60
70
2
6
2
6
-0.5 -0.8
-0.5 -0.8
5
6
5
6
0.7 1.1
0.7 1.1
2.85
0.9
3
1
70
-2
150
0.1
1.5
13.5
13.5
50
50
0.7
3.15 2.85
1.1 0.9
-10
300
0.4
2.2
13
12
150
150
1.2
3
1
70
-2
150
0.1
1.5
13.5
13.5
50
50
0.7
3.15
1.1
-10
300
0.4
2.2
Current Sense Section
Gain (Note 3 & 4)
Maximum Input Signal (Note 3)
Power Supply Rejection Ratio (Note 3)
Input Bias Current
Delay to Output (Note 2)
Output Section
Output Low Level
Output High Level
Rise Time (Note 2)
Fall Time (Note 2)
UVLO Saturation
V
OL
V
OH
T
R
T
F
V
SAT
13
12
150
150
1.2
(Electrical Characteristics continue next page.)
Copyright © 1995
Rev. 1.2a 10/25
3
PRODUCT DATABOOK 1996/1997
UC184xA/284xA/384xA
C
URRENT
M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
ELECTRICAL CHARACTERISTICS
Parameter
Under-Voltage Lockout Section
Start Threshold
Min. Operation Voltage After Turn-On
x842A/4A
x843A/5A
x842A/4A
x843A/5A
x842A/3A
x844A/5A
(Con't.)
Symbol
Test Conditions
UC184xA/284xA
UC384xA
Units
Min. Typ. Max. Min. Typ. Max.
15
7.8
9
7.0
94
47
16
8.4
10
7.6
96
48
17
9.0
11
8.2
100
50
0
0.5
17
30
14.5
7.8
8.5
7.0
94
47
16
8.4
10
7.6
96
48
17.5
9.0
11.5
8.2
100
50
0
0.5
17
V
V
V
V
%
%
%
mA
mA
V
PWM Section
Maximum Duty Cycle
Minimum Duty Cycle
Total Standby Section
Start-Up Current
Operating Supply Current
Zener Voltage
I
CC
V
Z
0.3
11
35
0.3
11
35
I
CC
= 25mA
30
Notes: 2. These parameters, although guaranteed, are not 100% tested in
production.
3. Parameter measured at trip point of latch with V
VFB
= 0.
4. Gain defined as: A
VOL
=
∆
V
COMP
; 0
≤
V
ISENSE
≤
0.8V.
∆
V
ISENSE
7. "Temperature stability, sometimes referred to as average temperature
coefficient, is described by the equation:
V
REF
(max.) - V
REF
(min.)
Temp Stability =
T
J
(max.) - T
J
(min.)
V
REF
(max.) & V
REF
(min.) are the maximum & minimum reference
voltage measured over the appropriate temperature range. Note that
the extremes in voltage do not necessarily occur at the extremes in
temperature."
5. Adjust V
CC
above the start threshold before setting at 15V.
6. Output frequency equals oscillator frequency for the UC1842A
and UC1843A. Output frequency is one half oscillator frequency
for the UC1844A and UC1845A.
BLOCK DIAGRAM
V
CC
*
34V
UVLO
Hysteresis
6V (1842A/4A)
0.8V (1843A/5A)
GROUND
**
UVLO
16V (1842A/4A)
8.4V (1843A/5A)
2.5V
S/R
5V
Ref
Internal
Bias
V
REF
5.0V
50mA
V
REF
Good Logic
R
T
/C
T
Oscillator
***
Error Amp
V
FB
COMP
CURRENT SENSE
2R
R
1V
S
R
Current Sense
Comparator
PWM
Latch
T
*
V
C
OUTPUT
**
POWER GROUND
* - V
CC
and V
C
are internally connected for 8 pin packages.
** - POWER GROUND and GROUND are internally connected for 8 pin packages.
*** - Toggle flip flop used only in x844A and x845A series.
4
Copyright © 1995
Rev. 1.2a 10/25
PRODUCT DATABOOK 1996/1997
UC184xA/284xA/384xA
C
URRENT
M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
CHARACTERISTIC CURVES
FIGURE 1.
— OSCILLATOR FREQUENCY vs. TIMING
RESISTOR
V
REF
8
Oscillator Frequency - (Hz)
1M
C
T
= 1nF
R
T
R
T
/C
T
4
C
T
GROUND 5
C
T
= 2.2nF
100k
10k
C
T
= 4.7nF
For R
T
> 5k, f
»
0
300
1.0k
3.0k
10.0k
30.0k
100k
1.72
R
T
C
T
Note: Output drive frequency is half the oscillator frequency for
the UCx844A/5A devices.
R
T
- (ohms)
FIGURE 2.
— MAXIMUM DUTY CYCLE vs. TIMING RESISTOR
100.0
Maximum Duty Cycle - (%)
80.0
60.0
40.0
20.0
0
300
1.0k
3.0k
10.0k
30.0k
100k
R
T
- (ohms)
Copyright © 1995
Rev. 1.2a 10/25
5
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