US1050-33
2-33
Rev. 1.1
10/27/00
TYPICAL APPLICATION
TYPICAL APPLICATION
DESCRIPTION
DESCRIPTION
The US1050-33 product is a low dropout three terminal
fixed 3.3V output regulator with minimum of 5A output
current capability. This product is specifically designed
to provide well regulated supply for low voltage IC appli-
cations requiring 3.3V output. The US 1050-33 is guar-
anteed to have <1.3V drop out at full load current
making it ideal to provide well regulated output with sup-
ply voltage as low as 4.6V input.
FEATURES
FEATURES
Guaranteed < 1.3V Dropout at Full Load
Current
Fast Transient Response
1% Voltage Reference Initial Accuracy
Output Current Limiting
Built-in Thermal Shutdown
APPLICATIONS
APPLICATIONS
Standard 3.3V Chip-Set and Logic Applications
5A LOW DROPOUT POSITIVE
FIXED 3.3V OUTPUT REGULATOR
Tj (C) 3 PIN PLASTIC 3 PIN PLASTIC 2 PIN PLASTIC 3 PIN PLASTIC
TO220 (T) TO263 (M) POWER FLEX (P) TO252 (D)
0 TO 150 US1050-33CT US1050-33CM US1050-33CP US1050-33CD
5V
3.3V / 5A
C1
330uF
C2
330uF
US1050-33
1050-33app1-1.1
1
2
3
Vout
Gnd
Vin
Typical application of US1050-33
US1050-33
2-34
Rev. 1.1
10/27/00
Note 1 : Low duty cycle pulse testing with Kelvin con-
nections are required in order to maintain accurate data.
Note 2 : Drop-out voltage is defined as the minimum
differential voltage between Vin and Vout required to main-
tain regulation at Vout. It is measured when the output
voltage drops 1% below its nominal value.
Note 3 : Minimum load current is defined as the mini-
mum current required at the output in order for the out-
put voltage to maintain regulation. Typically the resistor
dividers are selected such that it automatically main-
tains this current.
ABSOLUTE MAXIMUM RATINGS
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Vin) .................................................................. 7V
Power Dissipation ............................................ Internally Limited
Storage Temperature Range .............................. -65
C TO 150
C
Operating Junction Temperature Range .................. 0
C TO 150
C
PACKAGE INFORMATION
PACKAGE INFORMATION
3 PIN PLASTIC TO220 ( T ) 3 PIN PLASTIC TO263 ( M ) 2 PIN PLASTIC POWER FLEX ( P ) 3 PIN PLASTIC TO252 ( D )
JT
=2.7
C/W
JA
=60
C/W
JA
=35
C/W for 1" Square pad
JA
=70
C/W for 1" Square pad
JA
=70
C/W for 0.5" Sq pad
ELECTRICAL SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
Unless otherwise specified ,these specifications apply over ,Cin=1uF,Cout=10uF,and Tj=0 to 150
C.Typical
values refer to Tj=25
C.
PARAMETER
SYM
TEST CONDITION
MIN
TYP
MAX
UNITS
Output Voltage
V
o
Io=10mA,Tj=25
C,Vin=5V 3.267 3.300
3.330 V
Io=10mA, Vin=5V 3.234 3.300
3.366
Line Regulation
Io=10mA,4.7V<Vin<7V
0.2
%
Load Regulation (note 1)
Vin=5V,Vadj=0,10mA<Io<5A
0.4
%
Dropout Voltage
(note 2)
V
O
Note 2 , Io=5A
1.1
1.3
V
Current Limit
Vin=5V,dVo=100mV
5.1
A
Minimum Load Current
Vin=5V
5
10
mA
(note 3)
Thermal Regulation
30 mS PULSE,Vin-Vo=3V,Io=5A
0.01
0.02
%/W
Ripple Rejection
f=120HZ ,Co=25uF Tan
Io=2.5A,Vin-Vo=3V
60 70 dB
Adjust Pin Current Change
Io=10mA,Vin-Vo=1.5V,Tj=25
0.2
5
uA
Temperature Stability
Vin=5V,Vadj=0V,Io=10mA
0.5
%
Long Term Stability
Tj=125
C,1000 Hrs
0.3
1
%
RMS Output Noise
Tj=25
C 10hz<f<10khz
0.003
%Vo
1
4
3
FRONT VIEW
Gnd
Vin
Tab is
Vout
Gnd
Vout
Vin
Tab is
Vout
FRONT VIEW
1
2
3
1
2
3
FRONT VIEW
Gnd
Tab is
Vout
Vin
Vout
FRONT VIEW
1
4
3
Tab is
Vout
Adj
Vin
US1050-33
2-35
Rev. 1.1
10/27/00
APPLICATION INFORMATION
APPLICATION INFORMATION
Stability
The US1050-33 requires the use of an output capacitor
as part of the frequency compensation in order to make
the regulator stable. Typical designs for microproces-
sor applications use standard electrolytic capacitors with
a typical ESR in the range of 50 to 100 m
and an
output capacitance of 500 to 1000uF. Fortunately as
the capacitance increases, the ESR decreases result-
ing in a fixed RC time constant. The US1050-33 takes
advantage of this phenomena in making the overall regu-
lator loop stable.For most applications a minimum of
100uF aluminum electrolytic capacitor such as Sanyo
MVGX series ,Panasonic FA series as well as the
Nichicon PL series insures both stability and good tran-
sient response.
PIN DESCRIPTIONS
PIN DESCRIPTIONS
PIN # PIN SYMBOL PIN DESCRIPTION
1
Gnd
This pin must be connected to GND plane using a low inductance short connection.
2
Vout
The output of the regulator. A minimum of 10uF capacitor must be connected
from this pin to ground to insure stability.
3
Vin
The input pin of the regulator. Typically a large storage capacitor is connected
from this pin to ground to insure that the input voltage does not sag below the
minimum drop out voltage during the load transient response. This pin must
always be 1.3V higher than Vout in order for the device to regulate properly.
BLOCK DIAGRAM
BLOCK DIAGRAM
Figure 1 - Simplified block diagram of the US1050-33
Vin 3
1050-33blk1-1.0
1
Gnd
2 Vout
THERMAL
SHUTDOWN
CURRENT
LIMIT
1.25V
+
+
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