IRU1117CP [INFINEON]
800mA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR; 800毫安低压差正可调稳压器
| 型号： | IRU1117CP |
| 厂家： | 
Infineon |
| 描述： | 800mA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| 文件： | 总10页 (文件大小：70K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Data Sheet No. PD94136
IRU1117
800mA LOW DROPOUT POSITIVE
ADJUSTABLE REGULATOR
FEATURES
DESCRIPTION
Guaranteed < 1.2V Dropout at 800mA Load
Current
The IRU1117 is a low dropout, three-terminal adjustable
regulator with minimum of 800mA output current capa-
bility. This product is specifically designed to provide
well regulated supply for low voltage IC applications such
as high speed bus termination and low current 3.3V logic
supply. The IRU1117 is also well suited for other applica-
tions such as VGA and sound cards. The IRU1117 is
guaranteed to have <1.2V dropout at full load current
making it ideal to provide well regulated outputs of 2.5V
to 3.6V with 4.75V to 7V input supply.
Fast Transient Response
1% Voltage Reference Initial Accuracy
Built-In Thermal Shutdown
Available in SOT-223, D-Pak, Ultra Thin-PakTM
and 8-Pin SOIC Surface-Mount Packages
APPLICATIONS
VGA & Sound Card Applications
Low Voltage High Speed Termination Applications
Standard 3.3V Chip Set and Logic Applications
TYPICAL APPLICATION
D1
5V
C1
10uF
V
IN
3
2
1
IRU1117
V
OUT
2.85V / 800mA
R1
121
C2
10uF
Adj
R2
154
Figure 1 - Typical application of IRU1117 in a 5V to 2.85V SCSI termination regulator.
PACKAGE ORDER INFORMATION
TJ (°C)
2-PIN PLASTIC
TO-252 (D-Pak)
IRU1117CD
2-PIN PLASTIC
Ultra Thin-PakTM (P)
IRU1117CP
8-PIN PLASTIC
SOIC (S)
IRU1117CS
3-PIN PLASTIC
SOT-223 (Y)
IRU1117CY
0 To 150
Rev. 1.8
02/04/03
www.irf.com
1
IRU1117
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
2-PIN PLASTIC TO-252 (D-Pak)
2-PIN ULTRA THIN-PAKTM (P)
8-PIN PLASTIC SOIC (S)
3-PIN PLASTIC SOT-223 (Y)
FRONT VIEW
FRONT VIEW
TOP VIEW
TOP VIEW
3
3
V
IN
3
VIN
1
2
3
4
8
7
6
5
V
IN
V
OUT
OUT
OUT
OUT
VIN
Tab is
Tab is
NC
NC
Adj
V
Tab is
VOUT
2
1
VOUT
VOUT
VOUT
V
Adj
V
1
1
Adj
Adj
qJA=70°C/W for 0.5" Sq pad
qJA=70°C/W for 0.5" Sq pad
qJA=55°C/W for 1" Sq pad
qJA=90°C/W for 0.4" Sq pad
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over CIN=1µF, COUT=10µF, and TJ=0 to 1508C.
Typical values refer to TJ=258C.
PARAMETER
SYM
TEST CONDITION
MIN
TYP
MAX UNITS
Reference Voltage
VREF Io=10mA, TJ=258C, (VIN-Vo)=1.5V
Io=10mA, (VIN-Vo)=1.5V
Io=10mA, 1.3V<(VIN-Vo)<7V
VIN=3.3V, VADJ=0, 10mA<Io<800mA
∆VO Io=1A
1.238 1.250 1.262
1.225 1.250 1.275
V
Line Regulation
Load Regulation (Note 1)
Dropout Voltage (Note 2)
0.2
0.4
%
%
V
1.2
1.1
1.3
1.2
Io=800mA, Note 2
Current Limit
VIN=3.3V, ∆Vo=100mV
VIN=3.3V, VADJ=0V
1.1
60
A
mA
Minimum Load Current (Note 3)
Thermal Regulation
Ripple Rejection
5
10
30ms Pulse, VIN-Vo=3V, Io=800mA
f=120Hz, Co=25µF Tantalum,
Io=0.5A, VIN-Vo=3V
0.01
0.02
%/W
70
dB
Adjust Pin Current
IADJ
Io=10mA, VIN-Vo=1.5V, TJ=258C,
Io=10mA, VIN-Vo=1.5V
55
0.2
120
5
µA
µA
%
Adjust Pin Current Change
Temperature Stability
Long Term Stability
Io=10mA, VIN-Vo=1.5V, TJ=258C
VIN=3.3V, VADJ=0V, Io=10mA
TJ=1258C, 1000Hrs
0.5
0.3
1
%
RMS Output Noise
TJ=25°C, 10Hz<f<10KHz
0.003
%VO
Note 1: Low duty cycle pulse testing with Kelvin con- Note 3: Minimum load current is defined as the mini-
nections is required in order to maintain accurate data. mum current required at the output in order for the out-
put voltage to maintain regulation. Typically, the resistor
Note 2: Dropout voltage is defined as the minimum dif- dividers are selected such that it automatically main-
ferential voltage between VIN and VOUT required to main- tains this current. Typically, the values of the resistors
tain regulation at VOUT. It is measured when the output used to build the voltage divider are selected to ensure
voltage drops 1% below its nominal value.
that minimum load current is maintained.
Rev. 1.8
02/04/03
www.irf.com
2
IRU1117
PIN DESCRIPTIONS
PIN # PIN SYMBOL PIN DESCRIPTION
1
2
Adj
A resistor divider from this pin to the VOUT pin and ground sets the output voltage.
VOUT
The output of the regulator. A minimum of 10µF 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 dropout
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
VIN 3
2 VOUT
+
+
1.25V
CURRENT
LIMIT
THERMAL
SHUTDOWN
1 Adj
Figure 2 - Simplified block diagram of the IRU1117.
APPLICATION INFORMATION
Introduction
The IRU1117 adjustable Low Dropout (LDO) regulator is initial voltage, reducing the overall system cost with the
a three-terminal device which can easily be programmed need for fewer output capacitors. This is a key require-
with the addition of two external resistors to any volt- ment for today’s low voltage IC applications that typi-
ages within the range of 1.25 to 5.5V. This regulator cally need 3.3V supply and are often generated from the
only needs 1.3V differential to maintain output regula- 5V supply. Other applications such as high speed
tion. Unlike the first generation of the three-terminal regu- memory termination need to switch the load current from
lators such as LM117 that required 3V differential be- zero to full load in tens of nanoseconds at their pins,
tween the input and the regulated output.
which translates to an approximately 300 to 500ns cur-
rent step at the regulator. In addition, the output voltage
The IRU1117 is specifically designed to meet the fast tolerances are sometimes tight and they include the tran-
current transient needs as well as providing an accurate sient response as part of the specification.
Rev. 1.8
02/04/03
www.irf.com
3
IRU1117
Output Voltage Setting
to the load side, the effective resistance between the
The IRU1117 can be programmed to any voltages in the regulator and the load is multiplied by the factor of (1+R2/
range of 1.25V to 5.5V with the addition of R1 and R2 R1), or the effective resistance will be RP(eff)=RP×(1+R2/
external resistors according to the following formula:
R1). It is important to note that for high current applica-
tions, this can represent a significant percentage of the
overall load regulation and one must keep the path from
the regulator to the load as short as possible to mini-
mize this effect.
R2
R1
VOUT = VREF× 1+
+IADJ×R2
( )
Where:
PARASITIC LINE
VREF = 1.25V Typically
IADJ = 50µA Typically
R1 and R2 as shown in Figure 3:
RESISTANCE
RP
VIN
VOUT
VIN
IRU1117
VIN
VIN
VOUT
VOUT
Adj
RL
R1
R2
IRU1117
Adj
VREF
R 1
R 2
IADJ = 50uA
Figure 4 - Schematic showing connection
for best load regulation.
Figure 3 - Typical application of the IRU1117
for programming the output voltage.
Stability
The IRU1117 requires the use of an output capacitor as
The IRU1117 keeps a constant 1.25V between the out- part of the frequency compensation in order to make the
put pin and the adjust pin. By placing a resistor R1 across regulator stable. Typical designs for microprocessor ap-
these two pins a constant current flows through R1, add- plications use standard electrolytic capacitors with a
ing to the IADJ current and into the R2 resistor producing typical ESR in the range of 50 to 100mΩ and an output
a voltage equal to the (1.25/R1)×R2 + IADJ×R2 which capacitance of 500 to 1000µF. Fortunately as the ca-
will be added to the 1.25V to set the output voltage. pacitance increases, the ESR decreases resulting in a
This is summarized in the above equation. Since the fixed RC time constant. The IRU1117 takes advantage
minimum load current requirement of the IRU1117 is of this phenomenon in making the overall regulator loop
10mA, R1 is typically selected to be 121Ω resistor so stable. For most applications a minimum of 100µF alu-
that it automatically satisfies the minimum current re- minum electrolytic capacitor such as Sanyo MVGX se-
quirement. Notice that since IADJ is typically in the range ries, Panasonic FA series as well as the Nichicon PL
of 50µA it only adds a small error to the output voltage series insures both stability and good transient response.
and should only be considered when a very precise out-
put voltage setting is required. For example, in a typical Thermal Design
3.3V application where R1=121Ω and R2=200Ω the er- The IRU1117 incorporates an internal thermal shutdown
ror due to IADJ is only 0.3% of the nominal set point.
that protects the device when the junction temperature
exceeds the maximum allowable junction temperature.
Although this device can operate with junction tempera-
Load Regulation
Since the IRU1117 is only a three-terminal device, it is tures in the range of 1508C, it is recommended that the
not possible to provide true remote sensing of the output heat sink be selected such that during maximum con-
voltage at the load. Figure 4 shows that the best load tinuous load operation the junction temperature is kept
regulation is achieved when the bottom side of R2 is below this number. The example below for a SCSI termi-
connected to the load and the top side of R1 resistor is nator application shows the steps in selecting the proper
connected directly to the case or the VOUT pin of the regulator in a surface-mount package. (See IRU1015 for
regulator and not to the load. In fact, if R1 is connected non-surface-mount packages)
Rev. 1.8
02/04/03
www.irf.com
4
IRU1117
Assuming the following specifications:
To set the output DC voltage, we need to select R1 and
R2:
VIN = 5V
VF = 0.5V
4) Assuming R1 = 121Ω, 1%:
VOUT = 2.85V
IOUT(MAX) = 0.8A
TA = 358C
VOUT -1
2.85
-1
R2 =
×R1 =
×121 = 154.8Ω
( VREF ) ( 1.25 )
Where:
VF is the forward voltage drop of the D1 diode as
shown in Figure 5.
Select R2 = 154Ω, 1%
5) Calculate the power dissapation for the schottky di-
ode (D1):
+5V is significantly more than required to maintain drop-
out voltage across the IRU1117 when regulating VOUT to
2.85V. The "Extra" voltage means additional power is
dissapated in the IRU1117. The diode dissapates some
of this additional power, allowing the IRU1117 to run cooler.
PD = VF × IOUT
PD = 0.5× 0.8 = 0.4W
and select a suitable component.
D1
The steps for selecting the right package with proper
board area for heat sinking to keep the junction tem-
perature below 1358C is given as:
VOUT
VIN
5V
2.85V
C1
10uF
C2
22uF
IRU1117
R1
Adj
1) Calculate the maximum power dissipation using:
121
1%
PD = IOUT × (VIN - VF - VOUT)
R2
PD = 0.8 × (5 - 0.5 - 2.85) = 1.32W
154
1%
2) Calculate the maximum θJA allowed for our ex-
ample:
Figure 5 - Final Schematic for half of the
GTL+ termination regulator.
135 - 35
1.32
TJ - TA
PD
θJA(MAX) =
=
= 75.68C/W
Layout Consideration
3) Select a package from the data sheet with lower θJA
The output capacitors must be located as close to the
VOUT terminal of the device as possible. It is recom-
mended to use a section of a layer of the PC board as a
plane to connect the VOUT pin to the output capacitors to
prevent any high frequency oscillation that may result
due to excessive trace inductance.
than the one calculated in the previous step.
Selecting TO-252 (D-Pak) with at least 0.5" square
of 0.062" FR4 board using 1oz. copper has 70°C/W
which is lower than the calculated number.
IR WORLD HEADQUARTERS:233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105
TAC Fax: (310) 252-7903
Visit us at www.irf.com for sales contact information
Data and specifications subject to change without notice. 02/01
Rev. 1.8
02/04/03
www.irf.com
5
IRU1117
(D) TO-252 Package
2-Pin
K
A
B
C
L
M
N
78
458
D
J
E
O
P
Q
R
G
F
S
H
R1
SYMBOL MIN
MAX
A
B
6.477 6.731
5.004 5.207
0.686 0.838
7.417 8.179
C
D
E
C
L
9.703 10.084
0.635 0.889
2.286 BSC
F
G
H
J
4.521 4.623
∅1.52 ∅1.62
2.184 2.388
0.762 0.864
K
L
M
N
O
P
1.016
1.118
5.969 6.223
1.016
0
1.118
0.102
Q
R
R1
S
0.534 0.686
R0.31 TYP
R0.51 TYP
0.428 0.588
NOTE: ALL MEASUREMENTS
ARE IN MILLIMETERS.
Rev. 1.8
02/04/03
www.irf.com
6
IRU1117
(P) Ultra Thin-PakTM
2-Pin
A
A1
E
U
K
B
V
H
M
L
P
G
D
G1
N
C
R
C
L
SYMBOL
MIN
5.91
5.54
6.02
1.70
0.63
0.17
2.16
4.45
9.42
0.76
0.02
0.89
0.25
0.94
28
MAX
6.17
5.79
6.27
2.03
0.79
0.33
2.41
4.70
9.68
1.27
0.13
1.14
0.25
1.19
68
A
A1
B
C
D
E
G
G1
H
K
L
M
N
P
R
U
V
2.92
3.30
5.08 NOM
NOTE: ALL MEASUREMENTS
ARE IN MILLIMETERS.
Rev. 1.8
02/04/03
www.irf.com
7
IRU1117
(S) SOIC Package
8-Pin Surface Mount, Narrow Body
H
A
B
C
E
DETAIL-A
L
D
PIN NO. 1
DETAIL-A
I
0.38± 0.015 x 458
K
T
F
J
G
8-PIN
SYMBOL
MIN
MAX
A
B
C
D
E
F
G
H
I
4.80
4.98
1.27 BSC
0.53 REF
0.36
0.46
3.99
1.72
0.25
3.81
1.52
0.10
78 BSC
0.19
5.80
08
0.25
6.20
88
J
K
L
0.41
1.37
1.27
1.57
T
NOTE: ALL MEASUREMENTS
ARE IN MILLIMETERS.
Rev. 1.8
02/04/03
www.irf.com
8
IRU1117
(Y) SOT-223 Package
3-Pin
SYMBOL MIN
MAX
D
B
A
A1
B
1.498 1.702
0.02
2.895
0.637
0.11
3.15
0.85
B1
C
0.239 0.381
6.299 6.706
D
E
3.30
3.708
e
2.209 2.953
4.496 4.699
H
e1
H
E
6.70
08
7.30
108
Q
Q1
Q2
S
78
168
78
168
0.838
1.092
1.05
1.30
T
e
S
NOTE: ALL MEASUREMENTS
ARE IN MILLIMETERS.
e1
Q1
T
A
Q
C
B1
A1
Q2
Rev. 1.8
02/04/03
www.irf.com
9
IRU1117
PACKAGE SHIPMENT METHOD
PKG
PACKAGE
PIN
PARTS
PARTS
T & R
DESIG
DESCRIPTION
COUNT
PER TUBE
PER REEL
Orientation
D
P
S
Y
TO-252, (D-Pak)
Ultra Thin-PakTM
2
2
8
3
75
75
95
80
2500
2500
2500
2500
Fig A
Fig B
Fig C
Fig D
SOIC, Narrow Body
SOT-223
1
1
1
1
1
1
Feed Direction
Figure A
Feed Direction
Figure B
1
1
1
1
1
1
Feed Direction
Figure D
Feed Direction
Figure C
IR WORLD HEADQUARTERS:233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105
TAC Fax: (310) 252-7903
Visit us at www.irf.com for sales contact information
Data and specifications subject to change without notice. 02/01
Rev. 1.8
02/04/03
www.irf.com
10
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