ETC UCC2813-1

application
INFO
available
UCC2813-0/-1/-2/-3/-4/-5
UCC3813-0/-1/-2/-3/-4/-5
Low Power Economy BiCMOS Current Mode PWM
FEATURES
DESCRIPTION
• 100mA Typical Starting Supply Current
The UCC3813-0/-1/-2/-3/-4/-5 family of high-speed, low-power integrated circuits 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.
• 500mA Typical Operating Supply Current
• Operation to 1MHz
These devices have the same pin configuration as the UC3842/3/4/5
family, and also offer the added features of internal full-cycle soft start
and internal leading-edge blanking of the current-sense input.
• 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 UCC3802, UC3842, and
UC3842A
The UCC3813-0/-1/-2/-3/-4/-5 family offers a variety of package options,
temperature range options, choice of maximum duty cycle, and choice
of critical voltage levels. Lower reference parts such as the UCC3813-3
and UCC3813-5 fit best into battery operated systems, while the higher
reference and the higher UVLO hysteresis of the UCC3813-2 and
UCC3813-4 make these ideal choices for use in off-line power supplies.
The UCC2813-x series is specified for operation from –40°C to +85°C
and the UCC3813-x series is specified for operation from 0°C to +70°C.
ORDERING INFORMATION
Part Number
UCCx813-0
UCCx813-1
UCCx813-2
UCCx813-3
UCCx813-4
UCCx813-5
Maximum Duty Cycle
100%
50%
100%
100%
50%
50%
Reference Voltage
5V
5V
5V
4V
5V
4V
Turn-On Threshold
7.2V
9.4V
12.5V
4.1V
12.5V
4.1V
Turn-Off Threshold
6.9V
7.4V
8.3V
3.6V
8.3V
3.6V
BLOCK DIAGRAM
UDG-96134
SLUS161A - APRIL 1999 - REVISED JANUARY 2005
UCC2813-0/-1/-2/-3/-4/-5
UCC3813-0/-1/-2/-3/-4/-5
ABSOLUTE MAXIMUM RATINGS (Note 1)
CONNECTION DIAGRAMS
VCC Voltage (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0V
VCC Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.0mA
OUT Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1.0A
OUT Energy (Capacitive Load) . . . . . . . . . . . . . . . . . . . 20.0mJ
Analog Inputs (FB, CS) . . . . . . . . . . . . . . . . . . . . –0.3V to 6.3V
Power Dissipation at TA < +25°C (N Package). . . . . . . . . 1.0W
Power Dissipation at TA < +25°C (D Package). . . . . . . . 0.65W
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 Seconds). . . . . . . . . +300°C
DIL-8 or SOIC-8 (TOP VIEW)
N or D PACKAGE
Note 1: All voltages are with respect to GND. All currents are
positive into the specified terminal. Consult Unitrode Integrated
Circuits databook for information regarding thermal specifications and limitations of packages.
Note 2: In normal operation VCC is powered through a current
limiting resistor. Absolute maximum of 12V applies when VCC
is driven from a low impedance source such that ICC does not
exceed 30mA. The resistor should be sized so that the VCC
voltage under operating conditions is below 12V but above the
turn off threshold.
UCC2813
UCC3813
TEMPERATURE RANGE
–40°C TO +85°C
0°C TO +70°C
813
1
8
REF
FB
2
7
VCC
CS
3
6
OUT
RC
4
5
GND
TSSOP-8 (TOP VIEW)
PW PACKAGE
PACKAGES
N, D, PW
N, D, PW
ORDERING INFORMATION
UCC
COMP
1
COMP
REF
8
2
FB
VCC
7
3
CS
OUT
6
4
RC
GND
5
–
PRODUCT OPTION
PACKAGE
TEMPERATURE RANGE
ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C £ TA £ +85°C for
UCC2813-x; 0°C £ TA £ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND;
0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. TA = TJ.
PARAMETER
UCC2813-x
UCC3813-x
TEST CONDITIONS
MIN
UNITS
TYP
MAX
Reference Section
Output Voltage
TJ = +25°C, I = 0.2mA, UCCx813-0/-1/-2/-4
4.925
5.00
5.075
V
TJ = +25°C, I = 0.2mA, UCCx813-5
3.94
4.00
4.06
V
Load Regulation
0.2mA < I < 5mA
10
30
mV
Total Variation
UCCx813 -0-1/-2/-4 (Note 7)
4.84
5.00
5.10
V
UCCx813-5 (Note 7)
3.84
4.00
4.08
Output Noise Voltage
10Hz £ f £ 10kHz, TJ = +25°C (Note 9)
Long Term Stability
TA = +125°C, 1000 Hours (Note 9)
Output Short Circuit
5
–5
V
mV
70
mV
–35
mA
Oscillator Section
Oscillator Frequency
Temperature Stability
UCCx813-0/-1/-2/-4 (Note 4)
40
46
52
kHz
UCCx813-5 (Note 4)
26
31
36
kHz
2.25
2.40
(Note 9)
2.5
Amplitude Peak-to-Peak
Oscillator Peak Voltage
2.45
2
%
2.55
V
V
UCC2813-0/-1/-2/-3/-4/-5
UCC3813-0/-1/-2/-3/-4/-5
ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C £ TA £ +85°C for
UCC2813-x; 0°C £ TA £ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND;
0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. TA = TJ.
PARAMETER
UCC2813-x
UCC3813-x
TEST CONDITIONS
UNITS
MIN
TYP
MAX
COMP = 2.5V; UCCx813-0/-1/-2/-4
2.42
2.50
2.56
V
COMP = 2.0V; UCCx813-3/-5
1.92
2.0
2.05
V
2
mA
Error Amplifier Section
Input Voltage
Input Bias Current
–2
Open Loop Voltage Gain
60
COMP Sink Current
FB = 2.7V, COMP = 1.1V
0.4
COMP Source Current
FB = 1.8V, COMP = REF – 1.2V
–0.2
Gain Bandwidth Product
(Note 9)
80
dB
2.5
–0.5
–0.8
2
mA
mA
MHz
PWM Section
Maximum Duty Cycle
Minimum Duty Cycle
UCCx813-0/-2/-3
97
99
100
%
UCCx813-1/-4/-5
48
49
50
%
0
%
COMP = 0V
Current Sense Section
Gain
(Note 5)
1.10
1.65
1.80
V/V
Maximum Input Signal
COMP = 5V (Note 6)
0.9
1.0
1.1
V
200
nA
50
100
150
ns
1.32
1.55
1.70
V
0.45
0.90
1.35
V
–200
Input Bias Current
CS Blank Time
Over-Current Threshold
COMP to CS Offset
CS = 0V
Output Section
OUT Low Level
I = 20mA, all parts
0.1
0.4
V
I = 200mA, all parts
0.35
0.90
V
I = 50mA, VCC = 5V, UCCx813-3/-5
0.15
0.40
V
I = 20mA, VCC = 0V, all parts
0.7
1.2
V
I = –20mA, all parts
0.15
0.40
V
I = –200mA, all parts
1.0
1.9
V
I = –50mA,VCC = 5V, UCCx813-3/-5
0.4
0.9
V
Rise Time
CL = 1nF
41
70
ns
Fall Time
CL = 1nF
44
75
ns
OUT High VSAT
(VCC-OUT)
Undervoltage Lockout Section
Start Threshold (Note 8)
Stop Threshold (Note 8)
Start to Stop Hysteresis
UCCx813-0
6.6
7.2
7.8
V
UCCx813-1
8.6
9.4
10.2
V
UCCx813-2/-4
11.5
12.5
13.5
V
UCCx813-3/-5
3.7
4.1
4.5
V
UCC1813-0
6.3
6.9
7.5
V
UCC1813-1
6.8
7.4
8.0
V
UCCx813-2/-4
7.6
8.3
9.0
V
UCCx813-3/-5
3.2
3.6
4.0
V
UCCx813-0
0.12
0.3
0.48
V
UCCx813-1
1.6
2
2.4
V
UCCx813-2/-4
3.5
4.2
5.1
V
UCCx813-3/-5
0.2
0.5
0.8
V
3
UCC2813-0/-1/-2/-3/-4/-5
UCC3813-0/-1/-2/-3/-4/-5
ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C £ TA £ +85°C for
UCC2813-x; 0°C £ TA £ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND;
0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. TA = TJ.
PARAMETER
UCC2813-x
UCC3813-x
TEST CONDITIONS
MIN
TYP
UNITS
MAX
Soft Start Section
COMP Rise Time
FB = 1.8V, Rise from 0.5V to REF–1V
4
ms
Overall Section
Start-up Current
VCC < Start Threshold
0.1
0.23
mA
Operating Supply Current
FB = 0V, CS = 0V, RC = 0V
0.5
1.2
mA
15
VCC Internal Zener Voltage
ICC = 10mA (Note 8)
12
13.5
VCC Internal Zener Voltage Minus Start
Threshold Voltage
UCCx813-2/-4
0.5
1.0
V
V
Note 3: Adjust VCC above the start threshold before setting at 10V.
Note 4: Oscillator frequency for the UCCx813-0, UCCx813-2 and UCCx813-3 is the output frequency.
Oscillator frequency for the UCCx813-1, UCCx813-4 and UCCx813-5 is twice the output frequency.
D VCOMP
Note 5: Gain is defined by: A =
0 £ VCS £ 0.8V .
D VCS
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: Ensured by design. Not 100% tested in production.
PIN DESCRIPTIONS
COMP: COMP is the output of the error amplifier and the
input of the PWM comparator.
sense comparator during the 100ns interval immediately
following the rising edge of the OUT pin. This digital filtering, also called leading-edge blanking, means that in
most applications, no analog filtering (RC filter) is required on CS. Compared to an external RC filter technique, 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.
Unlike other devices, the error amplifier in the UCC3813
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 UCC3813 family features built-in full cycle Soft Start.
Soft Start is implemented as a clamp on the maximum
COMP voltage.
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.
RC: RC is the oscillator timing pin. For fixed frequency
operation, set timing capacitor charging current by connecting a resistor from REF to RC. Set frequency by connecting 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 functions.
CS: CS is the input to the current sense comparators.
The UCC3813 family has two different current sense
comparators: the PWM comparator and an over-current
comparator.
The UCC3813 family contains digital current sense filtering, which disconnects the CS terminal from the current
4
UCC2813-0/-1/-2/-3/-4/-5
UCC3813-0/-1/-2/-3/-4/-5
PIN DESCRIPTIONS (cont.)
The frequency of oscillation can be estimated with the
following equations:
UCCx813-0/-1/-2/-4: F =
low, total supply current will be higher, depending on
OUT current. Total VCC current is the sum of quiescent
VCC current and the average OUT current. Knowing the
operating frequency and the MOSFET gate charge (Qg),
average OUT current can be calculated from:
1.5
R ·C
UCCx813-3, UCCx813-5: F =
1.0
R ·C
I OUT = Qg · F .
To prevent noise problems, bypass VCC to GND with a
0.1 mF ceramic capacitor in parallel as close to the VCC
pin as possible. An electrolytic capacitor may also be
used in addition to the ceramic capacitor.
where frequency is in Hz, resistance is in W, and capacitance 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.
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.
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 capable of driving the gate of a power MOSFET with peak
currents exceeding ±750mA. OUT is actively held low
when VCC is below the UVLO threshold.
The high-current power driver consists of FET output devices, which can switch all of the way to GND and all of
the way to VCC. 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.
When VCC is greater than 1V and less than the UVLO
threshold, REF is pulled to ground through a 5kW resistor. This means that REF can be used as a logic output
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 0.1mF ceramic is required. Additional REF bypassing is required for external
loads greater than 2.5mA on the reference.
VCC: VCC is the power input connection for this device.
In normal operation VCC is powered through a current
limiting resistor. Although quiescent VCC current is very
To prevent noise problems with high speed switching
transients, bypass REF to ground with a ceramic capacitor very close to the IC package.
APPLICATION INFORMATION
UDG-96139
The UCC3813-0/-1/-2/-3/-4/-5 oscillator generates a sawtooth waveform on RC. The rise time is set by the time constant of RT
and CT. The fall time is set by CT and an internal transistor on-resistance of approximately 125W. During the fall time, the output is off and the maximum duty cycle is reduced below 50% or 100% depending on the part number. Larger timing capacitors
increase the discharge time and reduce the maximum duty cycle and frequency.
Figure 1. Oscillator.
5
UCC2813-0/-1/-2/-3/-4/-5
UCC3813-0/-1/-2/-3/-4/-5
APPLICATION INFORMATION (cont.)
4.00
3.98
3.96
VREF (V)
3.94
3.92
3.90
3.88
3.86
3.84
3.82
4
Figure 2. Error amplifier gain/phase response.
4.4
4.6
4.8
5
5.2
VCC (V)
5.4
5.6
5.8
6
Figure 5. UCC3813-3/-5 VREF vs. VCC; ILOAD = 0.5mA.
1000
Oscillator Freq. (kHz)
1000
Oscillator Freq. (kHz)
4.2
10
0p
F
100
20
0p
33
F
0p
F
100
10
0p
F
20
0p
F
33
0p
F
1n
F
1n
10
F
10
10
100
1000
10
RT (k )
1000
RT (k )
Figure 3. UCC3813-0/-1/-2/-4 oscillator frequency vs. RT
and CT.
Figure 6. UCC3813-3/-5 oscillator frequency vs. RT and
CT.
100
50
99.5
pF
00
pF
00
30
=3
pF
48
=1
48.5
=2
96.5
CT
pF
00
pF
97
pF
30
=3
00
=2
CT
97.5
=1
98
49
CT
CT
98.5
CT
Maximum Duty Cycle (%)
49.5
99
CT
Maximum Duty Cycle (%)
100
47.5
96
47
95.5
46.5
95
10
100
1000
10
Oscillator Frequency (kHz)
100
1000
Oscillator Frequency (kHz)
Figure 4. UCC3813-0/-2/-3 max. duty cycle vs. oscillator
frequency.
Figure 7. UCC3813-1/-4/-5 max. duty cycle vs. oscillator
frequency.
6
UCC2813-0/-1/-2/-3/-4/-5
UCC3813-0/-1/-2/-3/-4/-5
APPLICATION INFORMATION (cont.)
16
8
14
7
12
,
0V
C
VC
C
=1
F
8
C
VC
VC
5
ICC (mA)
ICC (mA)
10
nF
1
V,
6
F
1n
n
V, 1
=8
6
nF
1
V,
4
CC
3
Loa
0V, No
C=1
2
No Load
VCC = 8V,
1
VC
2
0
0
100
200
300
400
500
600
700
800
0
0
900 1000
=8
V
d
4
0
=1
VCC =
d
o Loa
10V, N
d
, No Loa
VCC = 8V
100
200
Oscillator Frequency (kHz)
300
400
500
600
700
800
900 1000
Oscillator Frequency (kHz)
Figure 8. UCC3813-0 ICC vs. oscillator frequency.
Figure 10. UCC3813-5 ICC vs. oscillator frequency.
1.1
500
450
COMP to CS Offset (Volts)
UCC1803/5
Dead Time (ns)
400
350
300
250
UCC1800/1/2/4
200
150
100
50
200
300
400
500
600
700
800
900
0.9
0.8
1000
CT (pF)
Slope = 1.8mV/°C
0.7
0.6
0
-55-50
0
100
1.0
-25
0
25
50
75
Temperature (°C)
Figure 9. Dead time vs. CT, RT = 100k.
Figure 11. COMP to CS offset vs. temperature,
CS = 0V.
7
100
125
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