IRU431LCS [INFINEON]
Two Terminal Voltage Reference, 1 Output, 1.24V, Trim/Adjustable, BIPolar, PDSO8, PLASTIC, SOIC-8;型号: | IRU431LCS |
厂家: | Infineon |
描述: | Two Terminal Voltage Reference, 1 Output, 1.24V, Trim/Adjustable, BIPolar, PDSO8, PLASTIC, SOIC-8 光电二极管 输出元件 |
文件: | 总6页 (文件大小:39K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
IRU431L/IRU431AL
LOW -VOLTAGE ADJUSTABLE
PRECISION SHUNT REGULATOR
PRELIMINARY DATASHEET
FEATURES
DESCRIPTION
SOT23-5 package
The IRU431L is a three-terminal adjustable shunt regu-
lator that can also be used as a precision voltage refer-
ence. Its output voltage may be set to any value be-
tween Vref(1.24V) and 6V with two external resistors as
shown in the typical application circuit. Other applica-
tions of this device include the use as a merged ampli-
fier and reference in applications such as a linear regu-
lator or as the secondary side controller in low voltage
power supply applications. The IRU431L only requires
80mA maximum quiescent current before regulating, mak-
ing it ideal as a voltage reference for battery type appli-
cations.
0.5% Voltage Reference Initial Accuracy
(IRU431AL)
Low Operational Cathode Current
(80mA max)
Unconditionally Stable with only 1mF
Adjustable Output from 1.24V to 15V
0.25W Typical Output Impedance
Pin to Pin Compatible with TLV431
APPLICATIONS
Precision Voltage Reference
Linear Regulator Controller
Secondary Side Controller for the Low Voltage
Power Supply Applications
TYPICAL APPLICATION
R1
Co
R2
IRU431
431app1-1.0
R1
R2
æ
è
ö
Vo = Vref ´ 1+
ç
÷
ø
Typical application of the IRU431L as a shunt regulator / voltage reference
PACKAGE ORDER INFORMATION
Ta (°C)
5-LEAD
SOT23-5
IRU431LCL5
PKG
MARK
431L
3-LEAD
SOT-23
IRU431LCL3
PKG
MARK
431L
8-PIN PLASTIC
SOIC
0 TO 70
0 TO 70
IRU431LCS
IRU431ALCS
IRU431ALCL5 431A
IRU431ALCL3 431A
Rev. 1.3
5/10/99
2-5
IRU431L/IRU431AL
ABSOLUTE MAXIMUM RATINGS
Input Voltage (V ) ................................................. 15V
in
Continuous Cathode Current Range ........................... -15mA to +15mA
Reference Current Range .......................................... -0.05mA to 1mA
Storage Temperature Range ..................................... -65°C TO 150°C
Operating Junction Temperature Range ......................
0°C TO 150°C
PACKAGE INFORMATION
5-PIN SOT-23 (L)
3-PIN SOT-23 (L3)
8-PIN PLASTIC SOIC (S)
TOP VIEW
TOP VIEW
TOP VIEW
Cathode
NC
1
2
3
4
8
7
6
5
Ref
1
2
3
5
2
Cathode
NC
NC
Anode
NC
3
Anode
Anode
NC
Anode
NC
1
Cathode
4
Ref
Ref
qJA = 450°C/W
qJA = 450°C/W
qJA=160°C/W
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over Ta=0 to 70 °C, CO =1mF. Typical values refer to
Ta=25 °C. Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the
ambient temperature.
PARAMETER
Reference Voltage
IRU431L
Reference Voltage
IRU431AL
Vref deviation over full
temperature range
Ratio of Vref change to
cathode voltage change
Reference pin current
Iref deviation over full
temperature range
Minimum cathode current
Off state cathode current
SYM
Vref
TEST CONDITION
IK=10mA, VKA=Vref, Ta=25°C
IK=10mA, VKA=Vref
IK=10mA, VKA=Vref, Ta=25°C
IK=10mA, VKA=Vref
VKA=Vref, IK=10mA
Note 1
MIN
TYP MAX
UNITS
1.228 1.240 1.252
1.221 1.240 1.259
1.234 1.240 1.246
1.228 1.240 1.252
V
Vref
V
mV
Vref(dev)
6
12
dVref/dVKA IK=10mA, dVKA=Vref to 6 V
-1
-3
mV/V
IK=10mA, R1=10kW, R2=open
IK=10mA, R1=10kW, R2=open
Note 1
0.15
0.05
1
0.3
mA
mA
Iref(dev)
IK(min)
Ioff
VKA=Vref
55
0.3
2.8
4
80
0.75
5
mA
mA
VKA=6V, Vref=0V
VKA=10V, Vref=0V
VKA=15V, Vref=0V
VKA=Vref, f<1 kHz,
IK=0.1 to 15 mA, Note 2
10
Dynamic impedance
Zka0
0.25
0.4
W
Note 1: The deviation parameters, Vref(dev) and Iref(dev) are
defined as the differences between the maximum and the minimum
values obtained over the rated temperature range. The average full
range temperature coeficient of the reference input voltage is de-
fined as:
Note 2:
Thedynamic impedance when VKA = Vref is defined as :
æ Vref(dev) ö
´ 106
ç
÷
DVKA
Zka0 =
è Vref(25° C)ø
DTA
a Vref =
DIK
When the device is operating with two external
resistors (see Figure 2), the total dynamic impedance
of the circuit is given by:
Where:
a Vref unit is ppm/°C
DTA is the rated operating free air temperature
of the device.
DV
DI
æ
R1ö
Zka =
= Zka0 ´ 1+
ç
÷
è
ø
R2
a Vref can be positive or negative depending on whether
minimum Vref or maximum Vref, respectively occurs at the
lower temperature.
Rev. 1.3
5/10/99
2-6
IRU431L/IRU431AL
PIN DESCRIPTIONS
SOT-23
5-PIN
PIN#
4
SOT-23
3-PIN
PIN#
1
8-PIN
SOIC
PIN#
8
Pin Description
A resistor divider from this pin to the cathode pin and
ground sets the output voltage.
PIN SYMBOL
Ref
The output of the shunt regulator. A minimum of 1mF
capacitor must be connected from this pin to Anode pin
to insure unconditional stability.
Ground pin. This pin must be connected to the lowest
potential in the system and all other pins must be at
higher potential with respect to this pin.
3
5
2
1
Cathode
Anode
NC
3
3,6
These pins are not connected internally.
1,2
NA
2,4,5,7
BLOCK DIAGRAM
Cathode
Ref
+
1.24V
431blk1-1.0
Anode
Figure 1 - Simplified block diagram of the IRU431L
Rev. 1.3
5/10/99
2-7
IRU431L/IRU431AL
The maximum value for the biasing resistor is calcu-
lated using the following equations:
APPLICATION INFORMATION
VMIN - VKA
Output Voltage Setting
RBMAX
=
IB MAX + ILMAX
IBMAX = IKMIN + IR
Where :
MIN
The IRU431L can be programmed to any voltages in the
range of 1.24 to 6V with the addition of R1 and R2 exter-
nal resistors according to the following formula:
V
= Minimum supply voltage
ILMAX = Maximum load current
IBMAX = Maximum bias current
IKMIN = Maximum value for the minimum
cathode current spec
R1
R2
æ
è
ö
Vo = VKA = Vref ´ 1+
+ Iref ´ R1
ç
÷
ø
The IRU431L keeps a constant voltage of 1.240V be-
tween the Ref pin and ground pin. By placing a resistor
R2 across these two pins a constant current flows
through R2, adding to the Iref current and into the R1
resistor producing a voltage equal to the (1.240/R2)*R1
+ Iref * R1 which will be added to the 1.240V to set the
output voltage as shown in the above equation. Since
the input bias current of the Ref pin is 0.5mA max, it
adds a very small error to the output voltage and for most
applications can be ignored. For example, in a typical
5V to 3.3V application where R2=1.21kW and R1=2kW
the error due to the Iadj is only 1mV which is about
0.03% of the nominal set point.
IR = Current through R1
Assuming R1=2kW as before,
3.3 - 1.24
IR =
= 1.03 mA
2
IBMAX = 0.08 + 1.03 = 1.11 mA
4.5 - 3.3
RB MAX
=
= 108 W
1.11+10
Selecting RB = 100 W
The maximum power dissipation of the resistor is
calculated under the maximum supply voltage as
follows:
2
VMAX - VKA
RB
PRB (MAX) =
V
IN
V
KA = V
O
RB
IK
IL
Co
R1
R2
Where :
IRU431
RL
VMAX = Maximum supply voltage
PRB (MAX) = Maximum RB power dissipation
2
6 - 3.3
431app2-1.0
PRB (MAX) =
= 73 mW
100
Thermal Design
The IRU431L is offered in the plastic 8-pin SOIC or the
surface mount SOT23-5 (L) packages. The 8-pin SOIC
package has the maximum power dissipation capability
of 775mW at Ta=25°C with the derating factor of -6.2mW
/ °C.The SOT23-5 package has the maximum power dis-
sipation capability of 150mW at Ta =25°C with the der-
ating factor of -1.2mW / °C.
Figure 2 - Typical application of the
IRU431L for programming the output voltage
Biasing Resistor (RB) Selection
The biasing resistor RB is selected such that it does
not limit the input current under the minimum input
supply and maximum load and biasing current.
An example is given below on how to properly select
the biasing resistor.
Assuming:
VMIN = 4.5 V
VMAX = 6 V
Table below summarizes the maximum power dissipa-
tion capability of each package versus ambient tempera-
ture.
Ambient Temperature (Ta) -°C
Pkg
25
40
50
60
70
8-Pin SOIC 775mW 682mW 620mW
558mW 496mW
VKA = 3.3 V
IL = 10mA
SOT23-5 150mW 132mW 120mW
108mW
96mW
Rev. 1.3
5/10/99
2-8
IRU431L/IRU431AL
In our previous example, the maximum power dissipa-
tion of the device is calculated under no load and maxi-
mum input supply condition.
The maximum power is calculated using the following
equation:
æ VMAX - VKA ö
PMAX = VKA ´
ç
÷
è
ø
RB
Where :
PMAX = Maximum power dissipation of the 431L
For our example :
æ 6 - 3.3ö
PMAX = 3.3 ´
= 89 mW
÷
ç
è
ø
100
As shown in the power dissipation table, both packages
can handle this power dissipation.
Stability
The IRU431L has many different regions of stability do-
main as a function of the cathode current which are typi-
cal characteristics of the three-terminal shunt regula-
tors. However, in general the device will be unconditionaly
stableforanycathodecurrentifthecapacitor, C O = 1mF
or bigger is connected from cathode to anode pins. If the
cathode current is always kept higher than 3mA under
minimum line and maximum load conditions, the CO can
be cut to 0.01mF and the system will be stable.
Rev. 1.3
5/10/99
2-9
IRU431L/IRU431AL
TYPICAL APPLICATION
I740 Application
Q1
V
IN
V
OUT
C1
C2
R4
R1
R2
R3
12V
U1
431app3-1.2
Figure 3- Low cost 3.3V to 2.7V output for Intel I740 application.
Ref Desig
U1
C1,2
R1
Description
Shunt Regulator
Capacitor
Resistor
Qty
1
2
Part #
Manuf
IRU431L
IR
Elect,220mF,6.3V,ECAOJFQ221 Panasonic
6.2kW, 5%, SMT
1
R2
Resistor
1
118W, 1%, SMT
R3,R4
HS1
Resistor
Heat Sink
2
100W, 1% SMT
Use minimum of 1" square copper pad area
for load current <4A
Rev. 1.3
5/10/99
2-10
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