US1205
2-1
Rev. 1.4
9/25/00
DESCRIPTION
DESCRIPTION
The US1205 device is an efficient linear voltage regula-
tor with better than 1% initial voltage accuracy, very low
dropout voltage and very low ground current designed
especially for hand held, battery powered applications.
Other features of the device are; TTL compatible enable/
shutdown control input, current limiting and thermal
shutdown.
The US1205 is available in fixed and adjustable output
voltage versions in a small SOT23-5 package.
300 mA LOW DROPOUT POSITIVE
ADJUSTABLE REGULATOR
FEATURES
FEATURES
SOT23 package
Stable with 2.2uF ceramic capacitor
1% Voltage Reference Accuracy
Only 270mV Dropout at 300 mA
170mV Dropout at 150mA
10nA Quiescent Current in Shutdown
Current Limit and Thermal Shutdown
Logic input Enable pin
APPLICATIONS
APPLICATIONS
Laptop, Notebook & Palmtop computers
Battery powered Equipments
PCMCIA Vcc & Vpp regulator
Concumer Electronics
High Efficiency Linear Power Supplies
PRELIMINARY DATASHEET
PACKAGE ORDER INFORMATION
PACKAGE ORDER INFORMATION
Tj (C) 5 LEAD SOT23 Output
SOT 23 Marking Voltage
0 TO 125 US1205CL AT00
Adj
0 TO 125 US1205-25CL AT25
2.5 V
0 TO 125 US1205-30CL AT30
3.0 V
0 TO 125 US1205-33CL AT33
3.3 V
0 TO 125 US1205-36CL AT36
3.6 V
TYPICAL APPLICATION
TYPICAL APPLICATION
Typical application of the US1205 ajustable.
Typical application of the US1205 Fixed voltage.
Vo=1.242
X
(1+R1/R2)
Vin
Vout
R1
R2
C1
2.2uF
C2
2.2uF
1205app1-1.1
S.D.
5
3
4
Vout
Adj
2
1
Vin
Gnd
En
Enable
3.3V
2.5V
C3
1000pF
C1
2.2uF
C2
2.2uF
1205app2-1.2
S.D.
Enable
5
3
4
Vout
Byp
2
1
Vin
Gnd
En
US1205
2-2
Rev. 1.4
9/25/00
ABSOLUTE MAXIMUM RATINGS
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Vin) ............................................................. 10V
Enable Input Voltage ........................................................... 10V
Storage Temperature Range ................................ -65C TO 150C
Operating Junction Temperature Range ...................... 0C TO 150C
PACKAGE INFORMATION
PACKAGE INFORMATION
5 PIN SOT23 ( L ) Adjustable 5 PIN SOT23 ( L ) Fixed
ELECTRICAL SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
Unless otherwise specified ,these specifications apply over ,Cin=Co=22uF, Io=100uA, Vinmin=2.5V(Adjustable
devices) Vin=Vo+1V(for fixed voltage devices), Vout=Vfb (for adjustable version only), Cbyp=470pF(for fixed output
versions only), Venb=2V and Ta=25
C. Typical values refer to Ta=25
C.Low duty cycle pulse testing are used
which keeps junction and case temperatures equal to the ambient temperature.
PARAMETER
SYM
TEST CONDITION
MIN
TYP MAX
UNITS
Reference Voltage
Vo
-1
1
%
See Table 1 for typical values
(Note 4)
-2
2
Line Regulation
dVi
Vo+1V<Vin<10
0.005
%/V
Load Regulation (note 1)
dVL
1mA<Io<100mA
0.8
%
100mA<Io<300mA
0.1
%
Dropout Voltage (note 2)
dVio
Io=100uA
10
50
mV
Io=100uA (Note 4)
13
70
mV
Io=50mA
85
110
mV
Io=50mA (Note 4)
100
140
mV
Io=150mA
170
220
mV
Io=150mA (Note 4)
204
260
mV
Io=300mA
270
350
mV
Io=300mA (Note 4)
324
400
mV
Ground Current (Note 3)
Iq
Ven=2V, Io=100uA
120
160
uA
Io=100uA (Note 4)
240
uA
Io=50mA
420
600
uA
Io=50mA (Note 4)
540
uA
Io=150mA
2200
2900
uA
Io=150mA (Note 4)
2900
uA
Io=300mA
7200
9500
uA
Io=300mA (Note 4)
9300
uA
Ground Current-S.D Activated
Iqsd
S.D pin<0.1V
0.1
uA
S.D pin=0.8V
8
Current Limit
Icl
Vo=0V
320
420
mA
Thermal Regulation
dVp
Vin=10V, Io=150mA,10 mS PULSE
0.05
%/W
Adjust Pin Current
Iadj
Vin=2.5V,Vo=Vadj
0.1
uA
Enable pin input LO voltage
Venl
Regulator OFF
0.8
V
Enable pin input HI voltage
Venh
Regulator ON
2
V
Enable pin input LO current
Venl=0V to 0.8V
0.01
uA
Enable pin input HI current
Venh=2V to Vin
20
uA
En
3
2
1
4
5
Adj
Gnd Vin
Vout
AT00
En
3
2
1
4
5
Byp
Gnd Vin
Vout
ATxx
JA
=220
C/W
JA
=220
C/W
US1205
2-3
Rev. 1.4
9/25/00
PIN # PIN SYMBOL PIN DESCRIPTION
A resistor divider from this pin to the Vout pin and ground sets
the output voltage.
A 470 to 1000pF bypass capacitor connected to this pin re-
duces the output noise.
The output of the regulator .A minimum of 2.2uF with max
ESR of 1 ohm capacitor must be connected from this pin to
ground to insure stability.
Ground pin. This pin must be connected to the lowest poten-
tial in the system & all other pins must be at higher potential
with respect to this pin.
Enable pin. A low signal or left open on this pin shuts down the
output.This pin must be tied HI or to Vin for normal operation.
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 minimumdrop out voltage dur-
ing the load transient response. This pin must always be higher
than Vout by at least the amount of the dropout voltage and
some margin in order for the device to regulate properly.
4
Adj
(Adjustable only)
4
Byp
(Fixed output only)
5
Vout
2
GND
3
En
1
Vin
5 LEAD Output
SOT 23 Voltage
US1205 1.242V
US1205-25 2.5 V
US1205-30 3.0 V
US1205-33 3.3 V
US1205-36 3.6 V
Table 1- Nominal output voltage v.s. part number
BLOCK DIAGRAM
BLOCK DIAGRAM
Note 3 : Ground current is the the regulator quiescent
current plus the pass transistor current. The total cur-
rent from the supply is the sum of the load current plus
the ground pin current.
Note 4 : The specification applies for the junction tem-
perature of 0 to +125
C.
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.
Vin
En
1205blk1-1.1
+
THERMAL
SHUTDOWN
1.242V
Vout
Adj
Gnd
Vin
En
1205blk2-1.0
+
THERMAL
SHUTDOWN
1.242V
Vout
Byp
Gnd
Figure 1- US1205 Adjustable block diagram
Figure 2- US1205 Fixed output block diagram
Pin DescRIPTIONS
Pin DescRIPTIONS
The output voltage of the adjustable device can be set using:
Vo=1.242
X
(1+R1/R2)
Where;
R1=Resistor connected from output to the Adj pin
R2=Resistor connected from Adj pin to GND
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