UCC383-ADJ [TI]
Low Dropout 3 Ampere Linear Regulator Family; 低压差3安培线性稳压器系列
| 型号： | UCC383-ADJ |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | Low Dropout 3 Ampere Linear Regulator Family |
| 文件： | 总8页 (文件大小：214K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
UCC283-3/-5/-ADJ
UCC383-3/-5/-ADJ
Low Dropout 3 Ampere Linear Regulator Family
FEATURES
DESCRIPTION
• Precision Positive Series Pass The UCC283-3/-5/-ADJ family of positive linear series pass regulators are tailored
Voltage Regulation
• 0.45V Dropout at 3A
• 50mV Dropout at 10mA
for low drop out applications where low quiescent power is important. Fabricated
with a BiCMOS technology ideally suited for low input to output differential applica-
tions, the UCC283-5 will pass 3A while requiring only 0.45V of typical input voltage
headroom (guaranteed 0.6V dropout). These regulators include reverse voltage
sensing that prevents current in the reverse direction. Quiescent current is always
less than 650µA. These devices have been internally compensated in such a man-
ner that the need for a minimum output capacitor has been eliminated.
• Quiescent Current Under
650µA Irrespective of Load
• Adjustable (5 Lead) Output
Voltage Version
UCC283-3 and UCC283-5 versions are in 3 lead packages and have preset outputs
at 3.3V and 5.0V respectively. The output voltage is regulated to 1.5% at room tem-
perature. The UCC283-ADJ version, in a 5 lead package, regulates the output volt-
age programmed by an external resistor ratio.
• Fixed (3 Lead) Versions for
3.3V and 5V Outputs
• Logic Shutdown Capability
• Short Circuit Power Limit of
Short circuit current is internally limited. The device responds to a sustained over-
current condition by turning off after a T delay. The device then stays off for a pe-
ON
riod, T , that is 32 times the T delay. The device then begins pulsing on and off
OFF
ON
3% •V • I
IN
SHORT
at the T /(T +T
) duty cycle of 3%. This drastically reduces the power dissipa-
ON
ON OFF
• Low V
Leakage
to V Reverse
tion during short circuit and means heat sinks need only accommodate normal op-
eration. On the 3 leaded versions of the device T is fixed at 750µs, on the
OUT
IN
ON
adjustable 5 leaded versions an external capacitor sets the on time — the off time
• Thermal Shutdown
is always 32 times T . The external timing control pin, CT, on the five leaded ver-
ON
sions also serves as a shutdown input when pulled low.
Internal power dissipation is further controlled with thermal overload protection cir-
cuitry. Thermal shutdown occurs if the junction temperature exceeds 165°C. The
chip will remain off until the temperature has dropped 20°C.
The UCC283 series is specified for operation over the industrial range of −40°C to
+85°C, and the UCC383 series is specified from 0°C to +70°C. These devices are
available in 3 and 5 pin TO-220 and TO-263 power packages.
BLOCK DIAGRAM
UDG-98133
SLUS215 - OCTOBER 1998
UCC283-3/-5/-ADJ
UCC383-3/-5/-ADJ
CONNECTION DIAGRAMS
ABSOLUTE MAXIMUM RATINGS
VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9V
CT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 to 3V
ADJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 to 9V
Storage Temperature . . . . . . . . . . . . . . . . . . . −65°C to +150°C
Junction Temperature. . . . . . . . . . . . . . . . . . . −55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
TO-263-3 (Front View)
TD Package
TO-263-5 (Front View)
TD Package
Currents are positive into, negative out of the specified termi-
nal. Consult Packaging Section of Databook for thermal limita-
tions and considerations of packages. All voltages are
referenced to GND.
See Note 1
TO-220-3 (Front View)
T Package
TO-220-5 (Front View)
T Package
See Note 1
See Note 1
Note 1: Tab = GND
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications hold for TA = 0°C to 70°C for the
UCC383-X series, −40°C to +85°C for the UCC283-X, VVIN = VVOUT + 1.5V, IOUT = 10mA, CIN = 10µF, COUT = 22µF. For the
283-ADJ, VVIN = 6.5V, CT = 750pF, TJ = TA.
PARAMETER
UCC283-5 Fixed 5V, 3A Family
Output Voltage
TEST CONDITIONS
MIN
TYP
MAX UNITS
TJ = 25°C
4.925
4.875
5
5.075
5.125
10
V
V
Over Temperature
VVIN = 5.15V to 9V
IOUT = 10mA to 3A
Line Regulation
Load Regulation
2
10
0.4
0.2
50
5
mV
mV
V
20
Dropout Voltage, VDROPOUT = VVIN − VVOUT IOUT = 3A, VOUT = 4.85V
IOUT = 1.5A, VOUT = 4.85V
0.6
0.45
150
6.5
5.5
5
V
IOUT = 10mA, VOUT = 4.85V
mV
A
Peak Current Limit
Overcurrent Threshold
Current Limit Duty Cycle
Overcurrent Time Out, TON
Quiescent Current
VVOUT = 0V
4
3
4
A
VVOUT = 0V
3
%
VVOUT = 0V
400
2.6
750
400
0
1400
650
75
µs
µA
mA
V
No load
Reverse Leakage Current
UVLO
0V < VVIN < VVOUT, VVOUT ≤ 5.1V, at VVOUT
VIN where VOUT passes current
2.8
3
2
UCC283-3/-5/-ADJ
UCC383-3/-5/-ADJ
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications hold for TA = 0°C to 70°C for the
UCC383-X series, −40°C to +85°C for the UCC283-X, VVIN = VVOUT + 1.5V, IOUT = 10mA, CIN = 10µF, COUT = 22µF. For the
283-ADJ, VVIN = 6.5V, CT = 750pF, TJ = TA.
PARAMETER
UCC283-3 Fixed 3.3V, 3A Family
Output Voltage
TEST CONDITIONS
MIN
TYP
MAX UNITS
TJ = 25°C
3.25
3.22
3.3
3.35
3.38
7
V
V
Over Temperature
VVIN = 3.45V to 9V
IOUT = 10mA to 3A
Line Regulation
Load Regulation
2
7
mV
mV
V
15
Dropout Voltage, VDROPOUT = VVIN VVOUT IOUT = 3A, VOUT = 3.15V
IOUT = 1.5A, VOUT = 3.15V
0.5
0.25
50
5
1
0.6
150
6.5
5.5
5
V
IOUT = 10mA, VOUT = 3.15V
mV
A
Peak Current Limit
VVOUT = 0V
4
3
Overcurrent Threshold
Current Limit Duty Cycle
Overcurrent Time Out, TON
Quiescent Current
4
A
VVOUT = 0V
3
%
VVOUT = 0V
400
2.6
750
400
0
1400
650
75
µs
µA
mA
V
No load
Reverse Leakage Current
UVLO
0V < VVIN < VVOUT, VVOUT ≤ 3.35V, at VVOUT
VIN where VOUT passes current
2.8
3
UCC283-ADJ Adjustable Output, 3A Family
Regulating Voltage at ADJ Pin
TJ = 25°C
1.23
1.22
1.25
1.27
1.28
3
V
V
Over Temperature
VVIN = VVOUT + 150mV to 9V
IOUT = 10mA to 3A
Line Regulation, at ADJ Input
Load Regulation, at ADJ Input
1
2
mV
mV
V
5
Dropout Voltage, VDROPOUT = VIN − VOUT VVIN > 4V, IOUT = 3A
VVIN > 3V, IOUT = 1.5A
0.4
0.2
50
5
0.6
0.45
150
6.5
5.5
5
V
VVIN > 3V, IOUT = 10mA
mV
A
Peak Current Limit
VVOUT = 0V, VIN = 6.5V
VVIN = 6.5V
4
3
Overcurrent Threshold
Current Limit Duty Cycle
Overcurrent Time Out, TON
Reverse Leakage Current
Bias current at ADJ Input
Quiescent Current
4
A
VVOUT = 0V
3
%
VVOUT = 0V, CT = 1500pF
0V < VVIN < VVOUT, VVOUT ≤ 9V, at VVOUT
750
0
µs
mA
nA
µA
V
100
250
650
100
400
0.45
40
2.8
No load
Shutdown Threshold
Quiescent Current in Shutdown
UVLO
At CT Input
0.25
2.6
VVIN = 10V
75
3
µA
V
VIN where VOUT passes current
3
UCC283-3/-5/-ADJ
UCC383-3/-5/-ADJ
PIN DESCRIPTIONS
ADJ: Adjust pin for the UCC283-ADJ version only. Feed- GND: Reference ground.
back pin for the linear regulator. Program the output volt-
age with R1 connected from ADJ to GND and R2
connected from VOUT to ADJ. Output voltage is given by:
VIN: Input voltage, This pin must be bypassed with a low
ESL/ESR 1µF or larger capacitor to GND. VIN can range
from (VOUT + V
) to 9V. If VIN is reduced to zero
DROPOUT
(
)
1.25V · R1+R2
while VOUT is held high, the reverse leakage from VOUT
to VIN is less than 75µA.
VOUT =
R1
CT: Short circuit timing capacitor and shutdown input for
the UCC283-ADJ version. Pulling CT below 0.25V turns
off the regulator and places it in a low quiescent current
mode. A timing capacitor, C, from CT to GND programs
the duration of the pulsed short circuit on-time. On-time,
VOUT: Regulated output voltage. A bypass capacitor is
not required at VOUT, but may be desired for good tran-
sient response. The bypass capacitor must not exceed a
maximum value in order to insure the regulator can start.
T
ON
, is approximately given by: T = 500k · C.
ON
ORDERING INFORMATION
Table I. Package Information
Temperature
Range
Package
Output Voltage
2: –40°C to +85°C
3: 0°C to +70°C
T: TO-220
3: 3.3V
5: 5V
TD: TO-263
ADJ: Adjustable
APPLICATION INFORMATION
Overview
large, the output voltage will not come into regulation
during the initial T
pulsed mode operation. The peak current limit, T
period, and load characteristics determine the maximum
value of output capacitor that can be charged. For a
constant current load the maximum output capacitance is
given as follows:
period and the UCC383 will enter
ON
The UCC383 family of low dropout linear (LDO) regula-
tors provide a regulated output voltage for applications
with up to 3A of load current. The regulators feature a
low dropout voltage and short circuit protection, making
their use ideal for demanding high current applications
requiring fault protection.
ON
T
)
·
V
(1)
(
Short Circuit Protection
C
= I -I
Farads
The UCC383 provides unique short circuit protection
circuitry that reduces power dissipation during a fault.
When an overload situation is detected, the device
enters a pulsed mode of operation at 3% duty cycle
reducing the heat sink requirements during a fault. The
UCC383 has two current thresholds that determine its
behavior during a fault as shown in Figure 1.When the
regulator current exceeds the overcurrent threshold for
For worst case calculations the minimum values of on
time (T ) and peak current limit (I ) should be used.
ON
CL
The adjustable version allows the T
adjusted with a capacitor on the CT pin:
time to be
ON
T
= 500, 000·C(mFarad) microseconds
(2)
(
)
T
= 500, 000·C mFarads
m
a period longer than T , the UCC383 shuts off for a
ON
period (T
) which is 32 times T . During an overload,
ON
OFF
For a resistive load (R ) the maximum output
LOAD
the regulator actively limits the maximum current to the
peak current limit value. The peak current limit is
nominally 1 Amp greater than the overcurrent threshold.
The regulator will continue in pulsed mode until the fault
is cleared as illustrated in Figure 1.
capacitor can be estimated from:
T
(3)
C
=
Farads
æ
ç
ö
÷
÷
÷
÷
ø
ç
1
R
· ln
ç
ç
è
V
Short Circuit Protection
1-
I
·R
A capacitive load on the regulator’s output will appear as
a short circuit during start-up. If the capacitance is too
4
UCC283-3/-5/-ADJ
UCC383-3/-5/-ADJ
APPLICATION INFORMATION (cont.)
Figure 1. UCC383 Short Circuit Timing
versions of the part, as well as the adjustable version
programmed to 3.0V.
Dropout Performance
Referring to the Block Diagram, the dropout voltage of
Figure 3. depicts the typical dropout performance of the
adjustable version with various output voltages and load
currents.
the UCC383 is equal to the minimum voltage drop (V to
IN
V
) across the N-Channel MOSFET. The dropout
OUT
voltage is dependent on operating conditions such as
load current, input and load voltages, as well as
Operating temperatures also effect the RDS
and
(ON)
temperature. The UCC383 achieves a low RDS
(ON)
dropout voltage of the UCC383. Figure 4. graphs the
typical dropout for the 3.3V and 5V versions with a 3A
load over temperature.
through the use of an internal charge-pump (V
) that
PUMP
drives the MOSFET gate. Figure 2 depicts typical
dropout voltages versus load current for the 3.3V and 5V
Vout = 3V
0.5
Vout = 3.3V
Vout = 5V
Iout = 1A
Iout = 1.5A
Iout = 3A
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.4
0.3
0.2
0.1
0
1
1.5
2
2.5
3
3.5
4
VOUT (V)
4.5
5
3
Iout (A)
Figure 2. UCC383 Typical Dropout vs. Load Current
Figure 3. Typical Dropout Voltage vs. I
and V
OUT VOUT
5
UCC283-3/-5/-ADJ
UCC383-3/-5/-ADJ
Voltage Programming and Shutdown Feature for Thermal Design
Adjustable Version
The Packing Information section of the data book con-
tains reference material for the thermal ratings of various
packages. The section also includes an excellent article
Thermal Characteristics of Surface Mount Packages, that
is the basis of the following discussion.
A typical application circuit based on the UCC383 adjust-
able version is shown in Figure 5. The output voltage is
externally programmed through a resistive divider at the
ADJ pin.
æ
ö
÷
R2
R1
Thermal design for the UCC383 includes two modes of
operation, normal and pulsed mode. In normal opera-
tion, the linear regulator and heat sink must dissipate
power equal to the maximum forward voltage drop multi-
plied by the maximum load current. Assuming a constant
current load, the expected heat rise at the regulator’s
junction can be calculated as follows:
(4)
ç
V
=1.25· 1+
volts
è
ø
The maximum programmed output voltage is constrained
by the 9V absolute rating of the IC (this includes the
charge pump voltage) and its ability to enhance the N-
Channel MOSFET. Unless the load current is below the
3A rating of the device, output voltages above 7V are not
recommended. The minimum output voltage can be pro-
grammed down to 1.25V, however, the input voltage must
always be greater than the UVLO of the part.
(5)
T
(q)=P
· q +q
(
°C
)
Where theta, (θ) is thermal resistance and P
is the
DISS
power dissipated. The thermal resistance of both the
TO-220 and TO-263 packages (junction to case) is 3 de-
grees Celsius per Watt. In order to prevent the regulator
from going into thermal shutdown, the case to ambient
theta must keep the junction temperature below 150°C.
If the LDO is mounted on a 5 square inch pad of 1 ounce
copper, for example, the thermal resistance from junction
to ambient becomes 60 degrees Celsius per Watt. If a
lower thermal resistance is required by the application,
the device heat sinking would need to be improved.
The adjustable version includes a shutdown feature, lim-
iting quiescent current to 40uA typical. The UCC383 is
shutdown by pulling the CT pin to below 0.25V. As shown
in Figure 4, a small logic level MOSFET or BJT transistor
in parallel with the timing capacitor can be driven with a
digital signal, putting the device in shutdown. If the CT
pin is not pulled low, the IC will internally pull up on the
pin enabling the regulator. The CT pin should not be
forced high, as this will interfere with the short circuit pro-
tection feature. Selection of the timing capacitor is ex-
plained in Short Circuit Protection.
The adjustable version can be used in applications re-
quiring remote voltage sensing (i.e. monitoring a voltage
other than or not directly tied to the VOUT pin). This is
possible since the inverting input of the voltage amplifier
(see Block Diagram) is brought out to the ADJ pin.
Vout = 3.3v
Vout = 5v
0.5
0.4
0.3
0.2
0.1
0
0.6
0.5
0.4
0.3
0.2
0
1
2
3
10
60
-40
LOAD CURRENT (AMPS)
TEMPERATURE (°C)
Figure 4. Typical dropout voltage vs. case
temperature with a 3A load
Figure 5. Typical application for the 5 pin adjustable
version.
6
UCC283-3/-5/-ADJ
UCC383-3/-5/-ADJ
When the UCC383 regulator is in pulsed mode due to an
overload or short circuit in the application, the maximum
average power dissipation is calculated as follows:
Ripple Rejection
Even though the UCC383 family of linear regulators are
not optimized for fast transient applications (Refer to
UC182 Fast LDO Linear Regulator), they do offer
significant power supply rejection at lower frequencies.
Figure 6 depicts ripple rejection performance in a typical
T
(6)
Watts
(
)
·I
P
= V –V
·
33·T
As seen in equation 6, the average power during a fault application. The performance can be improved with
is reduced dramatically by the duty cycle, allowing the additional filtering.
heat sink to be sized for normal operation. Although the
peak power in the regulator during the T period can be
ON
significant, the thermal mass of the package will gener-
ally keep the junction temperature from rising unless the
T
period is increased to tens of milliseconds.
ON
Figure 6. Typical supply current vs. load current.
UDG-94093
Figure 7. Ripple rejection vs. frequency.
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