www.fairchildsemi.com
FAN4041
Precision Micropower Shunt Voltage Reference
Features
•
•
•
•
•
•
Adjustable shunt reference
Tolerances to ±0.5% (25°C)
Low output noise
Low temperature coefficient to 100 ppm/°C max
Small packages
Extended operating current range
Description
The FAN4041 adjustable precision shunt references are ideal
for space- and cost-sensitive applications. They are available
with output voltage tolerances of 0.5% and 1%. They also
have excellent temperature coefficients, to 100ppm/°C for
the tighter tolerance grades. The FAN4041 series has an
extended operating current range, sinking as much as 25mA.
The FAN4041 series is available in SOT-23 and TO-92
packages.
Applications
•
•
•
•
•
Portable equipment
Disk drives
Instrumentation
Audio equipment
Data acquisition systems
Connection Diagrams
SOT-23
FB
1
3 –
+
2
Top View
TO-92
FB
3
+
2
–
1
Bottom View
REV. 1.0.5 3/25/04
FAN4041
PRODUCT SPECIFICATION
Absolute Maximum Ratings
1
Ratings are over full operating free-air temperature range unless otherwise noted.
Parameter
Continuous cathode current, IK
Power dissipation
Maximum Output Voltage
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)
-65
Min.
-30
Max.
30
12
150
300
Unit
mA
See Dissipation Rating Table
V
°C
°C
Notes:
1. Functional operation under these conditions is not implied. Permanent damage may occur if the device is subjected to
conditions outside these ratings.
Recommended Operating Conditions
Parameter
Continuous cathode current, IK
Operating temperature range in free air, TA
Output Voltage Range
Min.
0.07
-40
1.24
Max.
25
85
10
Unit
mA
°C
V
Dissipation Rating Table
Package
TO-92
SOT23
Power Rating
T
A
≤
25°C
550mW
306mW
Derating Factor
T
A
≥
25°C
5.5mW/°C
3.0mW/°C
Power Rating
T
A
= 70°C
302mW
168mW
Equivalent Schematic
+
+
_
V
REF
*
FB
*
_
*
External adjust components.
2
REV. 1.0.5 3/25/04
PRODUCT SPECIFICATION
FAN4041
Guaranteed Electrical Characteristics, FAN4041
(T
A
= 25°C unless otherwise specified, in free air)
The
•
denotes specifications which apply over the full operating temperature range.
Limits
Symbol
VREF
TCVRef
IRMIN
∆V
REF/∆T
∆V
REF
/∆IK
∆V
REF
/∆V
O
I
FB
ZKA
Parameter
Reference Voltage
Reference Voltage Tolerance
Mimimum Operating Current
Reference Voltage Temperature
Coefficient
Reference Voltage Change with
Operating Current
Reference Voltage Change with Output
Voltage
Feedback Current
Reverse Dynamic Impedance
Conditions
IK = 100µA, V
OUT
= 5V
IK = 100µA, V
OUT
= 5V
C
1.220
±6.2
±14
65
±100
2.0
8
12
-2.5
120
D
1.220
±12
±24
70
±150
2.5
10
15
-3.0
200
Units
V*
mV
mV
µA
ppm/°C
mV
mV
mV*
mV/V
nA
IK = 1mA
I
RMIN
≤
I
K
≤1mA
1mA
≤
I
≤
12mA
K
1mA
≤
I
K
≤
25mA
IK
=1mA
•
•
•
•
•
•
•
eN
∆V
REF
*Typical.
Wideband Noise
Reference Voltage Long-term Stability
IK=1mA, f=120Hz,
IAC=0.1IK
V
OUT
= V
REF
V
OUT
= 10V
IK=100µA, V
OUT
= V
REF
10Hz
≤
f
≤
10kHz
t=1000hrs, T=25°C,
IK=100µA
0.3
2
20
120
0.3
2
20
120
Ω*
Ω*
µVRMS*
ppm*
REV. 1.0.5 3/25/04
3
FAN4041
PRODUCT SPECIFICATION
Applications Information
The FAN4041 is a precision micro-power curvature-
corrected bandgap shunt voltage reference. For space critical
applications, the FAN4041 is available in the sub-miniature
SOT-23 package. The FAN4041 has been designed for stable
operation without the need of an external capacitor
connected between the
“+”
pin and the
“–”
pin. If, however,
a bypass capacitor is used, the FAN4041 remains stable.
The minimum operating current is 65µA for the FAN4041.
In a conventional shunt regulator application (Figure 1), an
external series resistor (R
S
) is connected between the supply
voltage and the FAN4041. R
S
determines the current that
flows through the load (I
L
) and the FAN4041 (I
Q
). Since
load current and supply voltage may vary, R
S
should be
small enough to supply at least the minimum acceptable I
Q
to the FAN4041 even when the supply voltage is at its
minimum and the load current is at its maximum value.
When the supply voltage is at its maximum and I
L
is at its
minimum, R
S
should be large enough so that the current
flowing through the FAN4041 is less than 25 mA.
R
S
should be selected based on the supply voltage, (V
S
), the
desired load and operating current, (I
L
and I
Q
), and the
FAN4041’s reverse breakdown voltage, V
R
.
V
S
– V
R
R
S
= --------------------
I
L
– I
Q
∆V
REF
/∆V
O
is found in the Electrical Characteristics and
is -2.5mV/V for the C-grade. You can get a more accurate
indication of the output voltage by replacing the value of
V
REF
in equation (1) with the value found using equation (2).
Note that the actual output voltage can deviate from that pre-
dicted using the typical value of
∆V
REF
/∆V
O
in equation (2):
for C-grade parts, the worst-case
∆V
REF
/∆V
O
is -2.5mV/V.
For D-grade parts, the worst-case
∆V
REF
/∆V
O
is -3.0mV/V.
Typical Applications
VS
RS
VR
FAN4041
IQ
IQ + IL
IL
Figure 1. Shunt Regulator
VS
RS
VO
R1
FAN4041
R2
The FAN4041 output voltage can be adjusted to any value in
the range of 1.220V through 10V. It is a function of the inter-
nal reference voltage (V
REF
) and the ratio of the external
feedback resistors as shown in Figure 2. The output voltage
is found using the equation
R2
-
V
O
= V
REF
------
+ 1
R1
(1)
R2
-
V
O
= V
REF
------
+ 1
R1
Figure 2. Adjustable Shunt Regulator
where V
O
is the output voltage. The actual value of the
internal V
REF
is a function of V
O
.
The “corrected” V
REF
is determined by
∆V
REF
V
REF
=
∆V
O
-----------------
+ V
Y
∆V
O
(2)
where
V
Y
= 1.220V
and
∆V
O
= V
O
– V
Y
4
REV. 1.0.5 3/25/04
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