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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 0.7A 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 1,200mV0.5% Low temperature coefficient 10ppm/C typ. Low Quiescent Current 0.7A max. No Output Capacitor Required Tolerates Capacitive Loads Bipolar Technology Package Outline NJM2825F : SOT-23-5 (MTP5)
PRODUCT VARIATION NJM2825
0.5%, IMIN=0.7A
NJM2823
0.4%, IMIN=60A
BLOCK DIAGRAM
CATHODE
PIN CONFIGURATION
NC 1 ANODE 2
VREF
5 CATHODE
NC 3
NJM2825F
4 FB
FB
ANODE
Ver.2009-03-05
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NJM2825
ABSOLUTE MAXIMUM RATINGS (Ta=25C) PARAMETER SYMBOL Cathode Voltage VKA Cathode Current IK Cathode-Anode Reverse Current -IK Power Dissipation PD Operating Temperature Range TOPR Storage Temperature Range TSTG MAXIMUM RATINGS 14 20 10 200 -40 +85 -40 +125 UNIT V mA mA mW C C
RECOMMENDED OPERATING CONDITIONS (Ta=25C) PARAMETER SYMBOL MIN. TYP. Cathode Voltage Cathode Current VKA IK VREF 0.7 - -
MAX. 13 12
UNIT V mA
ELECTRICAL CHARACTERISTICS (IK=0.8A,Ta=25C) PARAMETER SYMBOL TEST CONDITION Reference Voltage Load Regulation Reference Voltage Change vs. Cathode Voltage Change Minimum Operating Current Feedback Current Dynamic Impedance VREF VREF/ IK VREF/ VKA IMIN IFB ZKA VFB=VA VFB=VA, IMIN IK 200A VFB=VA, 200A IK 2mA VFB=VA, 2mA IK 12mA VREF VKA 13V, IK=2A R1=120k, R2=val (Note 1) VREF VKA 5V 5V VKA 13V R1=, R2=120k VFB=VA, IK=0.7A12mA (*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 A A nA
TEMPERATURE CHARACTERISTICS (IK=0.8A, Ta= -40C 85C) PARAMETER SYMBOL TEST CONDITION Reference Voltage Change (Note 2) Reference Voltage (Note 2) Feedback Current Change VREF_T VREF_T IFB_T VFB=VA VFB=VA R1=, R2=120k (*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: VREF***Reference voltage includes error. Note 2: Reference Voltage Change is defined as VREF_T [mV] = < Reference Voltage Change [ppm/C] > x <-40C 25C> x VREF 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)
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Ver.2009-03-05
NJM2825
TEST CIRCUIT
Input VKA IK VREF FB ANODE R2 CATHODE R1 VREF FB IFB ANODE Input VKA IK CATHODE
Fig.1 VKA=VREF to test circuit VFB=VA
Fig.2 VKA>VREF to test circuit
R2 VKA = VREF1 + + IFB x R2 R1
TYPICAL CHARACTERISTICS
Reference Voltage vs. Temperature (I =0.8A, V =V )
K FB A
1206 Reference Voltage VREF [mV] 1204 1202 1200 1198 1196 1194 -50
15 Reference Voltage Change VREF (mV) 12 9 6
Reference Voltage vs Cathode Current (VFB=VA )
Ta=-40 oC
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 Ik (mA)
100
Reference Voltage vs. Cathode Current Reference Voltage VREF (mV)
(mV)
Reference Voltage vs. Cathode Voltage 1202 1200 1198 1196 1194 1192 1190 1188 0 5 10 Cathode Voltage VK (V) 15 (R1=120k, R2=val, IK=2A, 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 Ik (A)
1
Ver.2009-03-05
Reference Voltage V
REF
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NJM2825
TYPICAL CHARACTERISTICS
Dynamic Impedance vs. Frequency Dynamic Impedance |ZKA| () 10 1 0.1 0.01
IK=0.8A Cout=0.047 F IK=10A Cout=0.1 F
(V =V , Ta=25 C)
FB A
o
2 Feedback Current IFB (nA)
IK=10A Cout=0 F
Feedback Current vs. Temperature (R1=Open, R2=120k, IK=0.8A)
IK=0.8A Cout=0 F
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 IK (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 (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 PD (mW) 200 150 100 50 0 0 25 50 75 100 o Ambient Temperature Ta ( C) (MTP5=Itself, Tj= 125oC)
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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.
VIN RS VOUT=VKA
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.
RS = VIN - VOUT [] IK + IOUT
R1
IK VREF CO
R2
IFB
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 VOUT = + 1 x VREF + IFB x 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 VREF = REF V KA x VOUT
VKA (V) 1.20 1.50 1.80 2.50 3.30 5.00
R1 (k) Open 120 120 120 120 120
R2 (k) 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 k. 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
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NJM2825 MEMO
[CAUTION] The specifications on this databook are only given for information , without any guarantee as regards either mistakes or omissions. The application circuits in this databook are described only to show representative usages of the product and not intended for the guarantee or permission of any right including the industrial rights.
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Ver.2009-03-05

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