Data Sheet No. PD94134
IRU1206 / IRU1207 / IRU1208 / IRU1209
1A VERY LOW DROPOUT POSITIVE
FIXED AND ADJUSTABLE REGULATORS
DESCRIPTION
The IRU1206 family of devices are ultra low dropout 1A
regulators using PNP transistor as the pass element.
These products are ideal when a single input supply is
only available and the dropout voltage is less than 1V,
exceeding the minimum dropout characteristics of NPN/
PNP hybrid regulators. One common application of these
regulators is where input is 3.3V and a 2.5V output is
needed.
Besides the low dropout of less than 0.5V, other fea-
tures of the family of the parts are: micro-power shut-
down capability and output UVLO detection where Flag
pin is switched low when output is below 5% of its nomi-
nal point.
FEATURES
Low Dropout Voltage (500mV at 1A)
1% Voltage Reference Accuracy
Low Ground Current
1mA Maximum Quiescent Current in Shutdown
(IRU1207, IRU1208)
Fast Transient Response
Current Limit and Thermal Shutdown
Error Flag Signal for Output out of Regulation
(IRU1207, IRU1208)
APPLICATIONS
2.5V Supply from 3.3V Input for the new
generation of Logic ICs
Computer Mother Board, Add-On Cards
High Efficiency Post Regulator in Switch Mode
Power Supply (SMPS)
TYPICAL APPLICATION
V
OUT
3
C2
V
OUT
IRU1206-
XX
Gnd
2
V
IN
1
V
IN
C1
Figure 1 - Typical application of the 1206-XX in a 3-Pin SOT-223 package.
PACKAGE ORDER INFORMATION
T
J
(°C)
0 To 125
0 To 125
0 To 125
0 To 125
0 To 125
0 To 125
0 To 125
0 To 125
Rev. 2.3
08/02/02
2-PIN TO-252
3-PIN
(D-PAK)
SOT-223 (Y)
IRU1206-18CD IRU1206-18CY
IRU1206-25CD IRU1206-25CY
IRU1206-33CD IRU1206-33CY
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
8-PIN PLASTIC
SOIC (S)
NA
NA
NA
IRU1207-18CS
IRU1207-25CS
IRU1207-33CS
IRU1208CS
IRU1209CS
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VOLTAGE
1.8V
2.5V
3.3V
1.8V
2.5V
3.3V
Adj
Adj
PIN FUNCTIONS
V
IN
, V
OUT
, Gnd
V
IN
, V
OUT
, Gnd
V
IN
, V
OUT
, Gnd
V
IN
, V
OUT
, Gnd, Enable, Flag
V
IN
, V
OUT
, Gnd, Enable, Flag
V
IN
, V
OUT
, Gnd, Enable, Flag
V
IN
, V
OUT
, Gnd, Flag, Adj
V
IN
, V
OUT
, Gnd, Enable, Adj
1
IRU1206 / IRU1207 / IRU1208 / IRU1209
ABSOLUTE MAXIMUM RATINGS
Input Voltage (V
IN
) .................................................... 12V
Enable Input Voltage ................................................ 12V
Storage Temperature Range ...................................... -65°C To 150°C
Operating Junction Temperature Range .....................
0°C To 135°C
PACKAGE INFORMATION
2-PIN PLASTIC TO-252 (D-Pak)
IRU1206
FRONT VIEW
3
3-PIN PLASTIC SOT-223 (Y)
IRU1206
TOP VIEW
3
V
OUT
V
OUT
Gnd
V
IN
Tab is
Gnd
1
V
IN
θ
JA
=70°C/W for
0.5" Sq pad
8-PIN PLASTIC SOIC (S)
IRU1208
TOP VIEW
Tab is
Gnd
2
1
θ
JA
=90°C/W for
0.4" Sq pad
IRU1207
TOP VIEW
IRU1209
TOP VIEW
Enable
V
IN
V
OUT
Flag
1
2
3
4
8
7
6
5
Gnd
Gnd
Gnd
Gnd
Flag
1
2
3
4
8
7
6
5
Gnd
Gnd
Gnd
Gnd
Enable
1
2
3
4
8
7
6
5
Gnd
Gnd
Gnd
Gnd
θ
JA
=55°C/W
for 1" Sq pad
V
IN
V
OUT
Adj
θ
JA
=55°C/W
for 1" Sq pad
V
IN
V
OUT
Adj
θ
JA
=55°C/W
for 1" Sq pad
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over C
IN
=C
OUT
=10mF, V
IN
=Vo+1V, V
OUT
=V
FB
(For adjustable
version only), and T
A
=25°C. Typical values refer to T
A
=25°C. Low duty cycle pulse testing is used which keeps
junction and case temperatures equal to the ambient temperature.
PARAMETER
Initial Voltage Accuracy
(see Table 1 for nominal values)
Line Regulation
Load Regulation (Note 1)
Output Voltage Temp Coef.
Dropout Voltage (Note 2)
SYM
Vo
DV
I
DV
L
TEST CONDITION
Io=10mA, T
A
=258C
(Note 4)
Vo + 1V<V
IN
<12
10mA<Io<1A
1mA<Io<150mA
MIN
-1
-1.3
TYP
MAX
1
1.3
1
0.7
0.5
100
200
400
650
3
15
50
1.1
1.4
2.1
2.3
0.1
1
UNITS
%
%
%
ppm/8C
mV
0.5
0.5
20
100
300
500
Ground Current (Note 3)
Current Limit
Minimum Input Voltage
IRU1208, IRU1209
Adjust Pin Current
Minimum Load Current
DV
O(T)
DV
I(O)
Io=100mA (Note 4)
Io=500mA (Note 4)
Io=1000mA (Note 4)
I
Q
V
IN
=Vo + 1 for all conditions:
Io=100mA (Note 4)
Io=500mA (Note 4)
Io=1000mA (Note 4)
I
CL
Vo=5% Below Regulation Point
V
IN(min)
I
ADJ
I
O(min)
V
IN
=2.5V, Vo=V
ADJ
(Note 4)
mA
A
V
mA
mA
2
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Rev. 2.3
08/02/02
IRU1206 / IRU1207 / IRU1208 / IRU1209
PARAMETER
IRU1207, IRU1209
Ground Current - SD Activated
Enable Pin Input LO Voltage
Enable Pin Input HI Voltage
Enable Pin Input LO Current
Enable Pin Input HI Current
IRU1207, IRU1208
Flag Output Threshold Voltage
Flag Output Hysteresis Voltage
Flag Output Saturation Voltage
SYM
I
Q(SD)
V
EN(L)
V
EN(L)
TEST CONDITION
Enable=Open
Regulator OFF (Note 4)
Regulator ON (Note 4)
V
EN(L)
=0V to 0.8V (Note 4)
V
EN(L)
=2V to Vin (Note 4)
MIN
TYP
0.01
2
0.1
100
5
0.8
400
230
2
600
MAX
1
0.8
UNITS
mA
V
V
mA
mA
%V
O
%V
O
mV
V
TH(FG)
V
HYS
Output Ramping Up
V
F(SAT)
Io=5mA
Io=500mA
Note 1:
Low duty cycle pulse testing with Kelvin con-
nections is required in order to maintain accurate data.
Note 2:
Dropout voltage is defined as the minimum dif-
ferential voltage between V
IN
and V
OUT
required to main-
tain regulation at V
OUT
. It is measured when the output
voltage drops 1% below its nominal value.
Note 3:
Ground current is the regulator quiescent cur-
rent plus the pass transistor current. The total current
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 +1258C.
PIN DESCRIPTIONS
PIN DESCRIPTION
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 0.6V higher than V
OUT
in order
for the device to regulate properly.
V
OUT
The output of the regulator. A minimum of 2.2mF capacitor must be connected from this pin
(All devices)
to ground.
Gnd
Ground pin. This pin must be connected to the lowest potential in the system and all other
(All devices)
pins must be at higher potential with respect to this pin.
Enable
Enable pin. A low signal or left open on this pin shuts down the output. This pin must be tied
(IRU1207, IRU1209) HI or to V
IN
for normal operation.
Flag
An open collector output that switches low when the output voltage drops about 4% below
(IRU1207, IRU1208) its expected regulated voltage.
Adj
A resistor divider from this pin to the V
OUT
pin and ground sets the output voltage.
(IRU1208, IRU1209)
PIN SYMBOL
V
IN
(All devices)
APPLICATION INFORMATION
Stability
The IRU120X series of regulators require the use of an
output capacitor as part of the frequency compensation
in order to make the regulator stable. A minimum of 2.2mF
capacitance and the ESR in the range of 0.5 to 2V in-
sures the stability of the system.
Part Number
IRU1206-18
IRU1206-25
IRU1206-33
IRU1207-18
IRU1207-25
IRU1207-33
IRU1208
IRU1209
Output
Voltage
1.8V
2.5V
3.3V
1.8V
2.5V
3.3V
1.24V
1.24V
Table 1 - Output voltage vs. part number.
Rev. 2.3
08/02/02
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3
IRU1206 / IRU1207 / IRU1208 / IRU1209
TYPICAL APPLICATION
V
OUT
3
C2
V
OUT
IRU1206-
XX
Gnd
2
V
IN
1
V
IN
C1
Note:
Tab must also be
connected to ground.
Figure 2 - Typical application of IRU1206.
Ref Desig
C1
C2
Description
Capacitor
Capacitor
Qty
1
1
Part #
10mF, Tantalum
10mF, Tantalum
Manuf
AVX
AVX
5
6
7
8
Gnd
Flag
4
3
R1
Error Flag
V
OUT
C2
Gnd
V
OUT
IRU1207
Gnd
V
IN
2
1
Gnd
Enable
SD
Enable
V
IN
C1
Figure 3 - Typical application of IRU1207.
Ref Desig
C1
C2
R1
Description
Capacitor
Capacitor
Resistor
Qty
1
1
1
Part #
10mF, Tantalum
10mF, Tantalum
10KV, 5%
Manuf
AVX
AVX
Panasonic
4
www.irf.com
Rev. 2.3
08/02/02
IRU1206 / IRU1207 / IRU1208 / IRU1209
TYPICAL APPLICATION
5
6
7
8
Gnd
Adj
4
3
2
R2
Gnd
V
OUT
V
OUT
R1
C2
R3
IRU1208
Gnd
V
IN
Gnd
Flag
1
Error Flag
V
IN
C1
Vo = 1.24
3
1 +
(
R1
R2
)
Figure 4 - Typical application of IRU1208 in 3.3V to 2.5V regulator.
Ref Desig
C1
C2
R1
R2
R3
Description
Capacitor
Capacitor
Resistor
Resistor
Resistor
Qty
1
1
1
1
1
Part #
10mF, Tantalum
10mF, Tantalum
127V, 1%
124V, 1%
10KV, 5%
Manuf
AVX
AVX
Rev. 2.3
08/02/02
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5
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