NJM2825
Precision Micropower Shunt Voltage Reference
■GENERAL
DESCRIPTION
NJM2825
is a precision and low quiescent current shunt voltage
reference.
Reference voltage form bandgap circuit has guaranteed the high
accuracy of the ±0.5% with trimming. In addition the temperature drift of
10ppm/°C typ. was actualized by the temperature compensating circuit.
The reference voltage circuit operates by consumed low quiescent current
of the 0.7µA for low power technology.
The Output capacitor is unnecessary by the phase compensating circuit
which is built in. Tolerates capacitive loads, it is easy to use for application.
It is suitable for data converters, instrumentation, and other applications
where precision reference is required.
■PACKAGE
OUTLINE
NJM2825F
■FEATURES
●
Precision Reference Voltage
1,200mV±0.5%
●
Low temperature coefficient
10ppm/°C typ.
●
Low Quiescent Current
0.7µA max.
●
No Output Capacitor Required
●
Tolerates Capacitive Loads
●
Bipolar Technology
●
Package Outline
NJM2825F : SOT-23-5 (MTP5)
■PRODUCT
VARIATION
NJM2825
±0.5%,
I
MIN
=0.7µA
NJM2823
±0.4%,
I
MIN
=60µA
■BLOCK
DIAGRAM
CATHODE
■PIN
CONFIGURATION
NC 1
ANODE 2
V
REF
5 CATHODE
NC 3
NJM2825F
4 FB
FB
ANODE
Ver.2009-03-05
-1-
NJM2825
■ABSOLUTE
MAXIMUM RATINGS (Ta=25°C)
PARAMETER
SYMBOL
Cathode Voltage
V
KA
Cathode Current
I
K
Cathode-Anode Reverse Current
-I
K
Power Dissipation
P
D
Operating Temperature Range
T
OPR
Storage Temperature Range
T
STG
MAXIMUM RATINGS
14
20
10
200
-40
∼
+85
-40
∼
+125
UNIT
V
mA
mA
mW
°C
°C
■RECOMMENDED
OPERATING CONDITIONS (Ta=25°C)
PARAMETER
SYMBOL MIN.
TYP.
Cathode Voltage
Cathode Current
V
KA
I
K
V
REF
0.7µ
–
–
MAX.
13
12
UNIT
V
mA
■ELECTRICAL
CHARACTERISTICS (I
K
=0.8µA,Ta=25°C)
PARAMETER
SYMBOL
TEST CONDITION
Reference Voltage
Load Regulation
Reference Voltage
Change vs. Cathode
Voltage Change
Minimum Operating
Current
Feedback Current
Dynamic Impedance
V
REF
∆V
REF
/
∆I
K
∆V
REF
/
∆V
KA
I
MIN
I
FB
Z
KA
V
FB
=V
A
V
FB
=V
A
, I
MIN
≤
I
K
≤
200µA
V
FB
=V
A
, 200µA
≤
I
K
≤
2mA
V
FB
=V
A
, 2mA≤ I
K
≤
12mA
V
REF
≤
V
KA
≤
13V, I
K
=2µA
R1=120kΩ, R2=val (Note 1)
V
REF
≤
V
KA
≤
5V
5V≤ V
KA
≤
13V
R1=∞, R2=120kΩ
V
FB
=V
A
, I
K
=0.7µA∼12mA
(*1)
(*1)
(*1)
(*1)
(*2)
(*2)
(*2)
(*2)
(*1)
MIN.
1194.0
–
–
–
–
–
–
–
–
TYP.
1200.0
0.2
0.7
3.4
-1
0.3
1
0.3
0.4
MAX.
1206.0
0.7
2
10
-2
0.7
2
1
1.1
UNIT
mV
mV
mV
mV
mV/V
µA
µA
nA
Ω
■TEMPERATURE
CHARACTERISTICS (I
K
=0.8µA, Ta= -40°C
∼
85°C)
PARAMETER
SYMBOL
TEST CONDITION
Reference Voltage
Change
(Note 2)
Reference Voltage
(Note 2)
Feedback Current
Change
∆V
REF_T
V
REF_T
I
FB_T
V
FB
=V
A
V
FB
=V
A
R1=∞, R2=120kΩ
(*1)
(*1)
(*2)
MIN.
–
1191.7
–
TYP.
0.8
10
1200.0
0.4
MAX.
2.3
30
1208.3
–
UNIT
mV
ppm/°C
mV
nA
Note 1:
V
REF
···Reference
voltage includes error.
Note 2: Reference Voltage Change is defined as
∆V
REF_T
[mV] =
±
< Reference Voltage Change [ppm/°C] >
×
<-40°C
∼
25°C>
×
V
REF
The maximum value of “Reference Voltage Change” is determined based on sampling evaluation from the 5 initial
production lots, and thus not tested in the production test. Therefore, these values are for the reference design
purpose only.
(*1): Test Circuit (Fig.1)
(*2): Test Circuit (Fig.2)
-2-
Ver.2009-03-05
NJM2825
■TEST
CIRCUIT
Input
V
KA
I
K
V
REF
FB
ANODE
R2
CATHODE
R1
V
REF
FB
I
FB
ANODE
Input
V
KA
I
K
CATHODE
Fig.1 V
KA
=V
REF
to test circuit
V
FB
=V
A
Fig.2 V
KA
>V
REF
to test circuit
R2
V
KA
=
V
REF
1
+
+
I
FB
×
R2
R1
■TYPICAL
CHARACTERISTICS
Reference Voltage vs. Temperature
(I =0.8µA, V =V )
K
FB
A
1206
Reference Voltage V
REF
[mV]
1204
1202
1200
1198
1196
1194
-50
15
Reference Voltage Change
∆V
REF
(mV)
12
9
6
Reference Voltage vs Cathode Current
(V
FB
=V
A
)
Ta=-40
o
C
Ta=25 C
o
3
Ta=75 C
o
-25
0
25 50 75 100 125
o
Ambient Temperature Ta ( C)
0
0.0001 0.001 0.01 0.1
1
10
Cathode Current I
k
(mA)
100
Reference Voltage vs. Cathode Current
Reference Voltage V
REF
(mV)
(mV)
Reference Voltage vs. Cathode Voltage
1202
1200
1198
1196
1194
1192
1190
1188
0
5
10
Cathode Voltage V
K
(V)
15
(R1=120kΩ, R2=val, I
K
=2µA, Ta=25 C)
o
1400
1200
1000
800
600
400
(V =V , Ta=25 C)
FB
A
o
0
0.2
0.4
0.6
0.8
Cathode Current I
k
(µA)
1
Ver.2009-03-05
Reference Voltage V
REF
-3-
NJM2825
■TYPICAL
CHARACTERISTICS
Dynamic Impedance vs. Frequency
Dynamic Impedance |Z
KA
| (Ω)
10
1
0.1
0.01
I
K
=0.8µA
Cout=0.047
µF
I
K
=10µA
Cout=0.1
µF
(V =V , Ta=25 C)
FB
A
o
2
Feedback Current I
FB
(nA)
I
K
=10µA
Cout=0
µF
Feedback Current vs. Temperature
(R1=Open, R2=120k
Ω
, I
K
=0.8
µ
A)
I
K
=0.8µA
Cout=0
µF
1.5
1
0.5
0
-50
0.001
0.0001
0.01
0.1
1
10
100
Frequency f (kHz)
1000
-25
0
25 50 75 100 125
o
Ambient Temperature Ta ( C)
Sefty Operating Boundary Condition
1
Cathode Current I
K
(
µ
A)
0.8
0.6
Stable Operation Region
0.4
0.2
Unstable Operation Region
0
0.001
0.01
0.1
1
Output Capacitance Co (
µ
F)
10
Note) Oscillation might occur while operating within the range
of safety curve.
So that, it is necessary to make ample margins by
taking considerations of fluctuation of the device.
(V =V , Ta=25 C)
FB
A
o
Ceramic Capacitor
Power Dissipation vs. Temperature
250
Power Dissipation P
D
(mW)
200
150
100
50
0
0
25
50
75
100
o
Ambient Temperature Ta ( C)
(MTP5=Itself, Tj=
∼
125
o
C)
-4-
Ver.2009-03-05
NJM2825
■Application
Information
The NJM2825 creates a highly accurate reference voltage, enabling a low power consumption application circuit to be
configured.
In the basic application (Fig.1) of the shunt regulator, a voltage drop is created by resistor Rs connected between the
input voltage and the NJM2825, and the output voltage (cathode – anode voltage = VKA) is controlled to a constant
value. The voltage drop due to Rs is determined by the total of the output current and the cathode current.
The feedback to the output voltage is controlled by the FB terminal, and the cathode current changes so that the set
voltage is obtained.
V
IN
R
S
V
OUT
=V
KA
As a result, Rs must conform to the following conditions.
*Minimum cathode current = 0.7 uA min
Conditions under which the input voltage is a minimum
and the output current is a maximum.
*Maximum cathode current = 12 mA max
Conditions under which the input voltage is a maximum
and the output current is a minimum.
The value of resistor Rs is obtained by means of the following formula.
V
−
V
OUT
R
S
=
IN
[
Ω
]
I
K
+
I
OUT
R1
I
K
V
REF
C
O
R2
I
FB
Fig.1 basic application
The output voltage can be set using any desired value between VREF and 13 V.
The output voltage is set according to the ratio between the values of the two external resistors, however an error
occurs depending upon the feedback current. The error can be minimized by combining two external resistors with low
resistance values. The formula for calculating the output voltage setting is shown below.
R2
V
OUT
=
+
1
×
V
REF
+
I
FB
×
R2
R1
As shown in the “reference voltage versus cathode voltage”
characteristics example, the reference voltage value has
negative characteristics. The reference voltage is corrected by
using
∆VREF/∆VKA
stipulated by the electrical characteristics.
∆
V
∆
V
REF
=
REF
∆
V
KA
×
V
OUT
V
KA
(V)
1.20
1.50
1.80
2.50
3.30
5.00
R1 (k
Ω
)
Open
120
120
120
120
120
R2 (k
Ω
)
Short
30.6
60.8
131
212
382
Table.1 Examples of output voltage settings at the standard
Table 1 shows an example of combining constants in the case where R1 is assumed to be 120 kΩ.
The error in the output voltage also varies with the accuracy of the resistors. In order to realize a highly accurate
application, the relative accuracy can be improved by either using accurate resistors or combining integrated resistors.
The NJM2825 contains an optimized phase compensation circuit. Consequently, in the basic application a stable
reference voltage is generated without the use of an output capacitor. As is indicated in the “dynamic impedance
versus frequency” characteristics, the impedance increases in proportion to the frequency. If necessary, connect an
output capacitor to reduce the high frequency impedance. You can connect a ceramic capacitor to obtain high stability,
but in this case be sure to use the NJM2825 in the stable operation region while referring to the “stable operation
boundary conditions” characteristics example.
Ver.2009-03-05
-5-
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