UCC1800/1/2/3/4/5
UCC2800/1/2/3/4/5
UCC3800/1/2/3/4/5
SLUS270C - MARCH 1999 - REVISED JANUARY 2005
FEATURES
100
A Typical Starting Supply Current
500
A Typical Operating Supply
Current
Operation to 1MHz
Internal Soft Start
Internal Fault Soft Start
Internal Leading-Edge Blanking of the
Current Sense Signal
1 Amp Totem-Pole Output
70ns Typical Response from
Current-Sense to Gate Drive Output
1.5% Tolerance Voltage Reference
Same Pinout as UC3842 and
UC3842A
DESCRIPTION
The UCC1800/1/2/3/4/5 family of high-speed, low-power integrated cir-
cuits contain all of the control and drive components required for off-line
and DC-to-DC fixed frequency current-mode switching power supplies
with minimal parts count.
These devices have the same pin configuration as the UC1842/3/4/5
family, and also offer the added features of internal full-cycle soft start
and internal leading-edge blanking of the current-sense input.
The UCC1800/1/2/3/4/5 family offers a variety of package options, tem-
perature range options, choice of maximum duty cycle, and choice of
critical voltage levels. Lower reference parts such as the UCC1803 and
UCC1805 fit best into battery operated systems, while the higher refer-
ence and the higher UVLO hysteresis of the UCC1802 and UCC1804
make these ideal choices for use in off-line power supplies.
The UCC180x series is specified for operation from 55
o
C to +125
o
C,
the UCC280x series is specified for operation from 40
o
C to +85
o
C, and
the UCC380x series is specified for operation from 0
o
C to +70
o
C.
Low-Power BiCMOS Current-Mode PWM
Part Number
Maximum Duty Cycle
Reference Voltage
Turn-On Threshold
Turn-Off Threshold
UCCx800
100%
5V
7.2V
6.9V
UCCx801
50%
5V
9.4V
7.4V
UCCx802
100%
5V
12.5V
8.3V
UCCx803
100%
4V
4.1V
3.6V
UCCx804
50%
5V
12.5V
8.3V
UCCx805
50%
4V
4.1V
3.6V
application
INFO
available
BLOCK DIAGRAM
UDG92009-3
2
UCC1800/1/2/3/4/5
UCC2800/1/2/3/4/5
UCC3800/1/2/3/4/5
DIL-8, SOIC-8 (Top View)
J or N, D Package
OUT
VCC
REF
GND
1
2
3
4
8
7
6
5
FB
COMP
CS
RC
ABSOLUTE MAXIMUM RATINGS (Note 1)
V
CC
Voltage (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0V
V
CC
Current (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . 30.0mA
OUT Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.0A
OUT Energy (Capacitive Load) . . . . . . . . . . . . . . . . . . . 20.0
J
Analog Inputs (FB, CS) . . . . . . . . . . . . . . . . . . . . 0.3V to 6.3V
Power Dissipation at T
A
< +25C (N or J Package) . . . . . 1.0W
Power Dissipation at T
A
< +25C (D Package). . . . . . . . 0.65W
Power Dissipation at T
A
< +25C (L Package) . . . . . . . 1.375W
Storage Temperature Range . . . . . . . . . . . . .
65C to +150C
Lead Temperature (Soldering, 10 Seconds) . . . . . . . . +300C
Note 1: Values beyond which damage may occur. All voltages
are with respect to GND. All currents are positive into
the specified terminal. Consult Unitrode databook for
information regarding thermal specifications and limita-
tions of packages.
Note 2: In normal operation V
CC
is powered through a current
limiting resistor. Absolute maximum of 12V applies
when V
CC
is driven from a low impedance source such
that I
CC
does not exceed 30mA (which includes gate
drive current requirement). The resistor should be
sized so that the V
CC
voltage, under operating condi-
tions is below 12V but above the turn off threshold.
COMP
FB
CS
RC
REF
VCC
OUT
GND
8
7
6
5
1
2
3
4
CONNECTION DIAGRAMS
TSSOP-8 (Top View)
PW Package
UCC
PRODUCT OPTION
PACKAGE
80
TEMPERATURE RANGE
ORDERING INFORMATION
Temperature Range
Available Packages
UCC180X
55C to +125C
J, L
UCC280X
40C to +85C
N, D, PW
UCC380X
0C to +70C
N, D, PW
TEMPERATURE AND PACKAGE SELECTION
LCC-20
(TOP VIEW)
L Package
PACKAGE PIN FUNCTION
FUNCTION
PIN
N/C
1
Comp
2
N/C
3-4
FB
5
N/C
6
CS
7
N/C
8-9
RC
10
N/C
11
PWR GND
12
GND
13
N/C
14
OUT
15
N/C
16
VCC
17
N/C
18-19
REF
20
3
UCC1800/1/2/3/4/5
UCC2800/1/2/3/4/5
UCC3800/1/2/3/4/5
ELECTRICAL CHARACTERISTICS
Unless otherwise stated, these specifications apply for 55
C
T
A
+125C for
UCC180x; 40C
T
A
+85C for UCC280x; 0C
T
A
+70C for UCC380x; V
CC
=10V (Note 3); RT=100k from REF to RC;
CT=330pF from RC to GND; 0.1 F capacitor from V
CC
to GND; 0.1 F capacitor from V
REF
to GND. T
A
=T
J
.
PARAMETER
TEST CONDITIONS
UCC180X
UCC280X
UCC380X
UNITS
MIN
TYP
MAX
MIN
TYP
MAX
Reference Section
Output Voltage
T
J
=+25C, I=0.2mA, UCCx800/1/2/4
4.925
5.00
5.075 4.925
5.00
5.075
V
T
J
=+25C, I=0.2mA, UCCx803/5
3.94
4.00
4.06
3.94
4.00
4.06
Load Regulation
0.2mA<I<5mA
10
30
10
25
mV
Line Regulation
T
J
=+25
C,
V
CC
=10V to Clamp (I
VCC
=25mA)
1.9
1.9
mV/V
T
J
=55C to +125C,
V
CC
=10V to Clamp (I
VCC
=25mA)
2.5
2.1
mV/V
Total Variation
UCCx800/1/2/4 (Note 7)
4.88
5.00
5.10
4.88
5.00
5.10
V
UCCx803/5 (Note 7)
3.90
4.00
4.08
3.90
4.00
4.08
V
Output Noise Voltage
10Hz
f
10kHz, T
J
=+25C (Note 9)
130
130
V
Long Term Stability
T
A
=+125C, 1000 Hours (Note 9)
5
5
mV
Output Short Circuit
5
35
5
35
mA
Oscillator Section
Oscillator Frequency
UCCx800/1/2/4 (Note 4)
40
46
52
40
46
52
kHz
UCCx803/5 (Note 4)
26
31
36
26
31
36
kHz
Temperature Stability
(Note 9)
2.5
2.5
%
Amplitude peak-to-peak
2.25
2.40
2.55
2.25
2.40
2.55
V
Oscillator Peak Voltage
2.45
2.45
V
Error Amplifier Section
Input Voltage
COMP=2.5V; UCCx800/1/2/4
2.44
2.50
2.56
2.44
2.50
2.56
V
COMP=2.0V; UCCx803/5
1.95
2.0
2.05
1.95
2.0
2.05
Input Bias Current
1
1
1
1
A
Open Loop Voltage Gain
60
80
60
80
dB
COMP Sink Current
FB=2.7V, COMP=1.1V
0.3
3.5
0.4
2.5
mA
COMP Source Current
FB=1.8V, COMP=REF1.2V
0.2
0.5
0.8
0.2
0.5
0.8
mA
Gain Bandwidth Product
(Note 9)
2
2
MHz
PWM Section
Maximum Duty Cycle
UCCx800/2/3
97
99
100
97
99
100
%
UCCx801/4/5
48
49
50
48
49
50
Minimum Duty Cycle
COMP=0V
0
0
%
Current Sense Section
Gain
(Note 5)
1.10
1.65
1.80
1.10
1.65
1.80
V/V
Maximum Input Signal
COMP=5V (Note 6)
0.9
1.0
1.1
0.9
1.0
1.1
V
Input Bias Current
200
200
200
200
nA
CS Blank Time
50
100
150
50
100
150
ns
Over-Current Threshold
1.42
1.55
1.68
1.42
1.55
1.68
V
COMP to CS Offset
CS=0V
0.45
0.90
1.35
0.45
0.90
1.35
V
4
UCC1800/1/2/3/4/5
UCC2800/1/2/3/4/5
UCC3800/1/2/3/4/5
ELECTRICAL CHARACTERISTICS
Unless otherwise stated, these specifications apply for 55
C
T
A
+125C for
UCC180x; 40C
T
A
+85C for UCC280x; 0C
T
A
+70C for UCC380x; V
CC
=10V (Note 3); RT=100k from REF to RC;
CT=330pF from RC to GND; 0.1 F capacitor from V
CC
to GND; 0.1 F capacitor from V
REF
to GND. T
A
=T
J
.
PARAMETER
TEST CONDITIONS
UCC180X
UCC280X
UCC380X
UNITS
Output Section
OUT Low Level
I=20mA, all parts
0.1
0.4
0.1
0.4
V
I=200mA, all parts
0.35
0.90
0.35
0.90
V
I=50mA, VCC=5V, UCCx803/5
0.15
0.40
0.15
0.40
V
I=20mA, VCC=0V, all parts
0.7
1.2
0.7
1.2
V
OUT High V
SAT
(V
CC
-OUT)
I=20mA, all parts
0.15
0.40
0.15
0.40
V
I=200mA, all parts
1.0
1.9
1.0
1.9
V
I=50mA,VCC=5V, UCCx803/5
0.4
0.9
0.4
0.9
V
Rise Time
C
L
=1nF
41
70
41
70
ns
Fall Time
C
L
=1nF
44
75
44
75
ns
Undervoltage Lockout Section
Start Threshold (Note 8)
UCCx800
6.6
7.2
7.8
6.6
7.2
7.8
V
UCCx801
8.6
9.4
10.2
8.6
9.4
10.2
V
UCCx802/4
11.5
12.5
13.5
11.5
12.5
13.5
V
UCCx803/5
3.7
4.1
4.5
3.7
4.1
4.5
V
Stop Threshold (Note 8)
UCCx1800
6.3
6.9
7.5
6.3
6.9
7.5
V
UCCx1801
6.8
7.4
8.0
6.8
7.4
8.0
V
UCCx802/4
7.6
8.3
9.0
7.6
8.3
9.0
V
UCCx803/5
3.2
3.6
4.0
3.2
3.6
4.0
V
Undervoltage Lockout Section (cont.)
Start to Stop Hysteresis
UCCx800
0.12
0.3
0.48
0.12
0.3
0.48
V
UCCx801
1.6
2
2.4
1.6
2
2.4
V
UCCx802/4
3.5
4.2
5.1
3.5
4.2
5.1
V
UCCx803/5
0.2
0.5
0.8
0.2
0.5
0.8
V
Soft Start Section
COMP Rise Time
FB=1.8V, Rise from 0.5V to REF1V
4
10
4
10
ms
Overall Section
Start-up Current
V
CC
< Start Threshold
0.1
0.2
0.1
0.2
mA
Operating Supply Current
FB=0V, CS=0V
0.5
1.0
0.5
1.0
mA
VCC Internal Zener Voltage
I
CC
=10mA (Note 8), (Note 10)
12
13.5
15
12
13.5
15
V
VCC Internal Zener Voltage Minus
Start Threshold Voltage
UCCx802/4 (Note 8)
0.5
1.0
0.5
1.0
V
Note 3: Adjust VCC above the start threshold before setting at 10V.
Note 4: Oscillator frequency for the UCCx800, UCCx802 and UCCx803 is the output frequency.
Oscillator frequency for the UCCx801, UCCx804 and UCCx805 is twice the output frequency.
Note 5: Gain is defined by:
A
V
V
V
V
COMP
CS
CS
=
0
0 8
. .
Note 6: Parameter measured at trip point of latch with Pin 2 at 0V.
Note 7: Total Variation includes temperature stability and load regulation.
Note 8: Start Threshold, Stop Threshold and Zener Shunt Thresholds track one another.
Note 9: Guaranteed by design. Not 100% tested in production.
Note 10: The device is fully operating in clamp mode as the forcing current is higher than the normal operating supply current.
5
UCC1800/1/2/3/4/5
UCC2800/1/2/3/4/5
UCC3800/1/2/3/4/5
PIN DESCRIPTIONS
COMP: COMP is the output of the error amplifier and the
input of the PWM comparator.
Unlike other devices, the error amplifier in the UCC3800
family is a true, low output-impedance, 2MHz operational
amplifier. As such, the COMP terminal can both source
and sink current. However, the error amplifier is internally
current limited, so that you can command zero duty cycle
by externally forcing COMP to GND.
The UCC3800 family features built-in full cycle Soft Start.
Soft Start is implemented as a clamp on the maximum
COMP voltage.
CS: CS is the input to the current sense comparators.
The UCC3800 family has two different current sense
comparators: the PWM comparator and an over-current
comparator.
The UCC3800 family contains digital current sense filter-
ing, which disconnects the CS terminal from the current
sense comparator during the 100ns interval immediately
following the rising edge of the OUT pin. This digital filter-
ing, also called leading-edge blanking, means that in
most applications, no analog filtering (RC filter) is re-
quired on CS. Compared to an external RC filter tech-
nique, the leading-edge blanking provides a smaller
effective CS to OUT propagation delay. Note, however,
that the minimum non-zero On-Time of the OUT signal is
directly affected by the leading-edge-blanking and the CS
to OUT propagation delay.
The over-current comparator is only intended for fault
sensing, and exceeding the over-current threshold will
cause a soft start cycle.
FB: FB is the inverting input of the error amplifier. For
best stability, keep FB lead length as short as possible
and FB stray capacitance as small as possible.
GND: GND is reference ground and power ground for all
functions on this part.
OUT: OUT is the output of a high-current power driver ca-
pable of driving the gate of a power MOSFET with peak
currents exceeding
750mA. OUT is actively held low
when V
CC
is below the UVLO threshold.
The high-current power driver consists of FET output de-
vices, which can switch all of the way to GND and all of
the way to V
CC
. The output stage also provides a very
low impedance to overshoot and undershoot. This means
that in many cases, external schottky clamp diodes are
not required.
RC: RC is the oscillator timing pin. For fixed frequency
operation, set timing capacitor charging current by con-
necting a resistor from REF to RC. Set frequency by con-
necting a timing capacitor from RC to GND. For best
performance, keep the timing capacitor lead to GND as
short and direct as possible. If possible, use separate
ground traces for the timing capacitor and all other func-
tions.
The frequency of oscillation can be estimated with the
following equations:
UCCx800/1/2/4:
F
R C
=
1 5
.
UCCx803, UCCx805:
F
R C
=
10
.
where frequency is in Hz, resistance is in ohms, and ca-
pacitance is in farads. The recommended range of timing
resistors is between 10k and 200k and timing capacitor is
100pF to 1000pF. Never use a timing resistor less than
10k.
To prevent noise problems, bypass VCC to GND with a
ceramic capacitor as close to the VCC pin as possible.
An electrolytic capacitor may also be used in addition to
the ceramic capacitor.
REF: REF is the voltage reference for the error amplifier
and also for many other functions on the IC. REF is also
used as the logic power supply for high speed switching
logic on the IC.
When V
CC
is greater than 1V and less than the UVLO
threshold, REF is pulled to ground through a 5k ohm re-
sistor. This means that REF can be used as a logic out-
put indicating power system status. It is important for
reference stability that REF is bypassed to GND with a
ceramic capacitor as close to the pin as possible. An
electrolytic capacitor may also be used in addition to the
ceramic capacitor. A minimum of 0.1
F ceramic is re-
quired. Additional REF bypassing is required for external
loads greater than 2.5mA on the reference.
To prevent noise problems with high speed switching
transients, bypass REF to ground with a ceramic capaci-
tor very close to the IC package.
VCC: V
CC
is the power input connection for this device.
In normal operation V
CC
is powered through a current
limiting resistor. Although quiescent V
CC
current is very
low, total supply current will be higher, depending on
OUT current. Total V
CC
current is the sum of quiescent
V
CC
current and the average OUT current. Knowing the
operating frequency and the MOSFET gate charge (Qg),
average OUT current can be calculated from:
I
Q
F
OUT
g
=
.
There should be a minimum of 1.0
m
F in parallel with a
0.1
m
F ceramic capacitor from V
CC
to ground located
close to the device
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