IRU431LCL3TR [INFINEON]
暂无描述;型号: | IRU431LCL3TR |
厂家: | Infineon |
描述: | 暂无描述 稳压器 电源电路 参考电压源 光电二极管 输出元件 |
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Data Sheet No. PD94118
IRU431L / IRU431AL
LOW -VOLTAGE ADJUSTABLE PRECISION
SHUNT REGULATOR
FEATURES
DESCRIPTION
The IRU431L family are three-terminal adjustable shunt
regulators that can also be used as precision voltage
SOT-23 Packages
Voltage Reference Initial Accuracy
(1% for IRU431L and 0.5% for IRU431AL)
Low Operating Cathode Current
(80µA max)
Unconditionally Stable with only 1µF
Adjustable Output from 1.24V to 15V
0.25Ω Typical Output Impedance
Pin to Pin Compatible with TLV431
references. Its output voltage may be set to any value
between VREF(1.24V) and 15V with two external resis-
tors as shown in the typical application circuit. Other
applications of this device include being used as a
merged amplifier and reference in applications such as
a linear regulator or as the secondary side controller in
low voltage power supply applications. The IRU431L only
requires 80µA maximum quiescent current before regu-
lating, making it ideal as a voltage reference for battery
type applications. The IRU431L has ±1% initial accu-
racy while IRU431AL provides ±0.5% initial accuracy.
APPLICATIONS
Precision Voltage Reference
Linear Regulator Controller
Secondary Side Controller for the low voltage
power supply applications
TYPICAL APPLICATION
RB
VIN
VOUT
R1
Co
R2
IRU431L
R1
Vo = VREF ×o 1 +
p
R2
Figure 1 - Typical application of the IRU431L as a shunt regulator / voltage reference.
PACKAGE ORDER INFORMATION
TA (°C)
0 To 70
0 To 70
5-PIN SOT-23 (L5)
IRU431LCL5
IRU431ALCL5
3-PIN SOT-23 (L3)
IRU431LCL3
IRU431ALCL3
Rev. 1.8
02/20/02
www.irf.com
1
IRU431L / IRU431AL
ABSOLUTE MAXIMUM RATINGS
Input Voltage (VIN) .................................................... 15V
Continuous Cathode Current Range .......................... -15mA To +15mA
Reference Current Range .......................................... -0.05mA To 1mA
Storage Temperature Range ...................................... -658C To 1508C
Operating Junction Temperature Range .....................
08C To 1508C
PACKAGE INFORMATION
5-PIN SOT-23 (L5)
3-PIN SOT-23 (L3)
TOP VIEW
TOP VIEW
2
Cathode
NC
NC
1
2
3
5
Anode
Anode
3
1
Ref
Cathode
4
Ref
qJA=256°C/W
qJA=336°C/W
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over TA=0 to 708C, Co=1µF. Typical values refer to TA=258C.
Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the ambient tempera-
ture.
PARAMETER
SYM
TEST CONDITION
MIN
TYP
MAX UNITS
Reference Voltage
IRU431L
Reference Voltage
IRU431AL
VREF
IK=10mA, VKA=VREF, TA=258C
IK=10mA, VKA=VREF
IK=10mA, VKA=VREF, TA=258C
IK=10mA, VKA=VREF
VKA=VREF, IK=10mA
Note 1
1.228 1.240 1.252
1.221 1.240 1.259
1.234 1.240 1.246
1.228 1.240 1.252
6
V
VREF
V
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
VREF(DEV)
mV
mV/V
∆VREF/∆VKA IK=10mA, ∆VKA=VREF to 6V
-1
-6
1
IK=10mA, R1=10KΩ, R2=open
IK=10mA, R1=10KΩ, R2=open
Note 1
0.15
0.05
µA
µA
IREF(DEV)
IK(MIN)
Ioff
VKA=VREF
55
0.6
1.8
3.2
0.25
80
0.75
5
10
0.4
µA
µA
VKA=6V, VREF=0V
VKA=10V, VREF=0V
VKA=15V, VREF=0V
VKA=VREF, f<1KHz,
IK=0.1 to 15mA, Note 2
Dynamic Impedance
ZKA0
Ω
Note 1: The deviation parameters, VREF(DEV) and IREF(DEV) Where:
are defined as the differences between the maximum ?αVREF? unit is ppm/8C
and the minimum values obtained over the rated tem- ∆TA is the rated operating free air temperature of the
perature range. The average full range temperature coef- device.
ficient of the reference input voltage is defined as:
αVREF can be positive or negative depending on whether
minimum VREF or maximum VREF respectively occurs at
the lower temperature.
VREF(DEV)
VREF(258C)
× 106
p
o
?αVREF? =
∆TA
Rev. 1.8
02/20/02
www.irf.com
2
IRU431L / IRU431AL
Note 2: The dynamic impedance when VKA=VREF is de- When the device is operating with two external resistors
fined as:
(See figure 3), the total dynamic impedance of the cir-
cuit is given by:
∆VKA
∆IK
?ZKA0? =
∆V
∆I
R1
R2
?ZKA? =
= ?ZKA0? ×o 1 +
p
PIN DESCRIPTIONS
SOT-23
3-PIN
PIN#
SOT-23
5-PIN
PIN#
PIN SYMBOL
PIN DESCRIPTION
4
3
5
1
2
3
Ref
Resistors from the Ref pin to the Cathode pin and to ground form a divider
that sets the output voltage.
Cathode
Anode
The output of the shunt regulator. A capacitor of 1µF minimum value 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.
1, 2
NA
NC
These pins are not connected internally.
BLOCK DIAGRAM
Cathode
Ref
+
1.24V
Anode
Figure 2 - Simplified block diagram of the IRU431L.
Rev. 1.8
02/20/02
www.irf.com
3
IRU431L / IRU431AL
APPLICATION INFORMATION
Output Voltage Setting
An example is given below on how to properly select the
The IRU431L can be programmed to any voltages in the biasing resistor.
range of 1.24 to 15V with the addition of R1 and R2
external resistors according to the following formula:
Assuming:
VMIN = 4.5V
R1
R2
VMAX = 6V
VKA = 3.3V
IL = 10mA
Vo = VKA = VREF ×o 1 +
p + IREF × R1
The IRU431L keeps a constant voltage of 1.240V be-
tween the Ref pin and ground pin. By placing a resistor The maximum value for the biasing resistor is calcu-
R2 across these two pins a constant current flows lated using the following equations:
through R2, adding to the IREF current and into the R1
resistor producing a voltage equal to:
VMIN - VKA
IB(MAX) + IL(MAX)
RB(MAX) =
1.240
R2
IB(MAX) = IK(MIN) + IR
o
p × R1 + IREF × R1
Where:
which will be added to the 1.240V to set the output volt-
age as shown in the above equation. Since the input
bias current of the Ref pin is 0.5µA max, it adds a very
small error to the output voltage and for most applica-
tions can be ignored. For example, in a typical 5V to
3.3V application where R2=1.21KΩ and R1=2KΩ the
error due to the IADJ is only 1mV which is about 0.03% of
the nominal set point.
VMIN = Minimum supply voltage
IL(MAX) = Maximum load current
IB(MAX) = Maximum bias current
IK(MIN) = Maximum value for the minimum
cathode current spec
IR = Current through R1
Assuming R1 = 2KΩ as before,
R
B
3.3 - 1.24
IR =
= 1.03mA
V
IN
VKA = VOUT
2
I
L
IK
R1
R2
IB(MAX) = 0.08 + 1.03 = 1.11mA
4.5 - 3.3
Co
RL
IRU431L
RB(MAX) =
= 108Ω
1.11 +10
Select RB = 100Ω
Figure 3 - Typical application of the
IRU431L for programming the output voltage.
The maximum power dissipation of the resistor is
calculated under the maximum supply voltage as
follows:
(VMAX - VKA)2
Biasing Resistor (RB) Selection
PRB(MAX) =
RB
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.
Where:
VMAX = Maximum supply voltage
PRB(MAX) = Maximum RB power dissipation
(6 - 3.3)2
100
PRB(MAX) =
= 73mW
Rev. 1.8
02/20/02
www.irf.com
4
IRU431L / IRU431AL
Thermal Design
Stability
The IRU431L is offered in the surface mount SOT-23 (L) The IRU431L has many different domains of stability as
packages. The SOT-23 package has the maximum power a function of the cathode current. As is typical of three-
dissipation capability of 150mW at TA=25°C with the de- terminal shunt regulators, the IRU431L has many do-
rating factor of -1.2mW / °C.
mains of stability. The actual domain in which any prac-
tical circuit operates is related to cathode current. In
The table below summarizes the maximum power dissi- general the device will be unconditionally stable for any
pation capability of each package versus ambient tem- cathode current if a capacitor, 1µF or larger, is connected
perature.
between the cathode and the anode. If the cathode cur-
rent is always higher than 3mA under minimum line and
maximum load conditions, the capacitor value can be
reduced to 0.01µF and the system will be stable.
Ambient Temperature (TA) -8C
Pkg
25
40
50
60
70
SOT-23
150mW 132mW 120mW
108mW
96mW
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:
PMAX = VKA × o VMAX - VKA p
RB
Where:
PMAX = Maximum power dissipation of the 431L
For our example:
6 - 3.3
PMAX = 3.3 × o
p = 89mW
100
As shown in the power dissipation table, both packages
can handle this power dissipation.
Rev. 1.8
02/20/02
www.irf.com
5
IRU431L / IRU431AL
TYPICAL APPLICATION
Q1
V
IN
V
OUT
C1
C2
R4
R1
R2
R3
12V
U1
Figure 4 - Low cost 3.3V to 2.7V output.
Ref Desig
U1
C1, C2
R1
Description
Shunt Regulator
Capacitor
Resistor
Qty
1
2
Part #
Manuf
IRU431L
IR
Elect,220µF, 6.3V, ECAOJFQ221 Panasonic
6.2KΩ, 5%, SMT
1
R2
Resistor
1
118Ω, 1%, SMT
R3, R4
HS1
Resistor
Heat Sink
2
100Ω, 1% SMT
Use minimum of 1" square copper pad area
for load current <4A
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
02/20/02
www.irf.com
6
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