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LT1389 Nanopower Precision Shunt Voltage Reference
FEATURES
s s s s s
DESCRIPTION
The LT (R)1389 is a nanopower, precision shunt voltage reference. The bandgap reference uses trimmed precision thin-film resistors to achieve 0.05% initial voltage accuracy. An improved curvature correction technique guarantees 10ppm/C maximum temperature drift. Advances in design, processing and packaging techniques guarantee 800nA operation and low temperature cycling hysteresis. The LT1389 does not require an output compensation capacitor, but is stable with capacitive loads. Low dynamic impedance makes the LT1389 reference easy to use from unregulated supplies. The LT1389 reference can be used as a high performance upgrade to the LM185/LM385, LT1004, LT1034 and LT1634 where lowest power and guaranteed temperature drift is required.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Initial Voltage Accuracy: 0.05% Low Operating Current: 800nA Low Drift: 10ppm/C Max Less Than 1 Dynamic Impedance Available in 1.25V and 2.5V SO-8 Packages
APPLICATIONS
s s s s
Portable Meters Precision Regulators A/D and D/A Converters Calibrators
TYPICAL APPLICATION
Temperature Drift
2.0
REFERENCE VOLTAGE CHANGE (mV)
1.5 1.0 0.5 0 - 0.5 -1.0 -1.5 - 2.0 0
IR = 0.8A VOUT = 1.25V
5V 4.7M VOUT 1.25V LT1389-1.25
1389 TA01
10
U
U
U
20
40 50 30 TEMPERATURE (C)
60
70
1389 TA02
1
LT1389
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW DNC* 1 DNC* 2 DNC* 3 GND 4 8 DNC* 7 DNC* 6 VOUT 5 GND
Operating Current 1.25V ............................................................... 20mA 2.5V ................................................................. 20mA Forward Current................................................... 20mA Operating Temperature Range ..................... 0C to 70C Storage Temperature Range (Note 2) ... - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LT1389ACS8-1.25 LT1389BCS8-1.25 LT1389BCS8-2.5 S8 PART MARKING 389A1 389B1 389B2
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125C, JA = 190C/ W
*Connected internally. Do Not Connect external circuitry to these pins. Consult factory for Industrial and Military grade parts.
AVAILABLE OPTIO S
TEMPERATURE 0C to 70C ACCURACY (%) 0.05 0.05 0.05 TEMPERATURE COEFFICIENT (ppm/C) 10 20 20 PACKAGE TYPE S8 LT1389ACS8-1.25 LT1389BCS8-1.25 LT1389BCS8-2.5 PART MARKING S8 389A1 389B1 389B2
1.25V ELECTRICAL CHARACTERISTICS
PARAMETER Reverse Breakdown Voltage CONDITIONS
(Note 3)
MIN 1.24937 - 0.05
q q
TYP 1.250 1.250 1.250 0.20 0.20 0.3 0.3 4 4 0.25 0.25 20
MAX 1.25062 0.05 1.25149 0.12 1.25237 0.19 0.4 1.0 1.0 2.0 0.6 10 20 0.7 1.5
UNITS V % V % V % mV mV mV mV A ppm/C ppm/C VP-P
LT1389ACS8/LT1389BCS8 (IR = 0.8A) LT1389ACS8 (IR = 0.8A) LT1389BCS8 (IR = 0.8A)
1.24849 - 0.12 1.24762 - 0.19
Reverse Breakdown Change with Current (Note 4)
0.8A IR 200A
q
200A IR 2mA
q
Minimum Operating Current Temperature Coefficient Reverse Dynamic Impedance (Note 5) Low Frequency Noise (Note 6) LT1389ACS8 (IR = 0.8A) LT1389BCS8 (IR = 0.8A) 0.8A IR 2mA
q q q q
IR = 0.8A, 0.1Hz f 10Hz
2
U
W
U
U
WW
U
W
LT1389
2.5V ELECTRICAL CHARACTERISTICS
PARAMETER Reverse Breakdown Voltage CONDITIONS LT1389BCS8 (IR = 0.9A) LT1389BCS8 (IR = 0.9A) Reverse Breakdown Change with Current (Note 4) 0.9A IR 200A
(Note 3)
MIN 2.49875 - 0.05
q
TYP 2.500 2.500 0.2 0.2 0.3 0.3 8 0.25 0.25 40
MAX 2.50125 0.05 2.50475 0.19 0.5 1.5 1.0 2.5 0.7 20 0.75 2
UNITS V % V % mV mV mV mV A ppm/C VP-P
2.49525 - 0.19
q
200A IR 2mA
q
Minimum Operating Current Temperature Coefficient Reverse Dynamic Impedance (Note 5) Low Frequency Noise (Note 6) IR = 0.9A 0.9A IR 2mA
q q q
IR = 0.9A, 0.1Hz f 10Hz
The q denotes specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: If the part is stored outside of the specific operating temperature range, the output may shift due to hysteresis.
Note 3: ESD (Electrostatic Discharge) sensitive device. Use proper ESD handling precautions. Note 4: Output requires 0.1F for operating current greater than 1mA. Note 5: This parameter is guaranteed by "reverse breakdown change with current" test. Note 6: Peak-to-peak noise is measured with a single highpass filter at 0.1Hz and 2-pole lowpass filter at 10Hz.
3
LT1389 1.25V TYPICAL PERFOR A CE CHARACTERISTICS
Reverse Characteristics
1.0 2.0 TA = - 40C TO 85C
REFERENCE VOLTAGE CHANGE (mV)
REVERSE VOLTAGE CHANGE (mV)
REVERSE CURRENT (A)
0.8
0.6
0.4
0.2
0
0
0.8 0.4 1.2 REVERSE VOLTAGE (V)
1.6
1389-1.25 G01
Reverse Dynamic Impedance
1000 TA = 25C f = 25Hz 100
DYNAMIC IMPEDANCE (k)
DYNAMIC IMPEDANCE ()
FORWARD VOLTAGE (V)
10
1
0.1 0.001
0.01 0.1 1 REVERSE CURRENT (mA)
10
1389-1.25 G04
0.1Hz to 10Hz Noise
25 20 NOISE VOLTAGE (V/DIV) 15 10 5 0 -5 -10 -15 - 20 - 25 0 10 20 30 40 50 TIME (SEC) 60 70
5V 0V
IR = 0.8A
1389-1.25 G07
4
UW
1.5 1.0 0.5 0 - 0.5 -1.0 -1.5 100 10 1 0.1 1.5V 1V 0.5V 0V
Temperature Drift
1.2 1.0 0.8
Reverse Voltage Change vs Current
- 40C 0.6 0.4 0.2 0 0.001 25C
IR = 250A
IR = 0.8A - 2.0 - 40
85C
-20
40 20 TEMPERATURE (C)
0
60
80
0.01 0.1 1 REVERSE CURRENT (mA)
10
1389-1.25 G03
1389-1.25 G02
Dynamic Impedance vs Frequency
1.0 TA = 25C 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 10
1389-1.25 G05
Forward Characteristics
TA = 25C
IR = 0.8A COUT = 0F
IR = 0.8A COUT = 0.047F IR = 10A COUT = 0.1F
IR = 10A COUT = 0F 0.01 0.01 0.1 1 FREQUENCY (kHz)
0 0.001
0.01 0.1 1 10 FORWARD CURRENT (mA)
100
1389-1.25 G06
Response Time
1.5V 1V 0.5V 0V 5V 0V IR = 0.8A COUT = 0F 1ms/DIV
1389-1.25 G08
Response Time
IR = 0.8A COUT = 0.1F
200ms/DIV
1389-1.25 G09
LT1389 2.5V TYPICAL PERFOR A CE CHARACTERISTICS
Reverse Characteristics
1000 4.0 TA = - 40C TO 85C
REVERSE VOLTAGE CHANGE (mV)
REVERSE VOLTAGE CHANGE (mV)
800
REVERSE CURRENT (nA)
600
400
200
0
0
0.4
0.8
1.2 1.6 2.0 REVERSE VOLTAGE (V)
2.4
2.8
1389-2.5 G01
Reverse Dynamic Impedance
1000 TA = 25C f = 25Hz 100
DYNAMIC IMPEDANCE ()
FORWARD VOLTAGE (V)
100
DYNAMIC IMPEDANCE (k)
10
1
0.1 0.001
0.01 0.1 1 REVERSE CURRENT (mA)
10
1389-2.5 G04
0.1Hz to 10Hz Noise
100 80 NOISE VOLTAGE (V/DIV) 60 40 20 0 - 20 - 40 - 60 - 80 -100 0 10 20 30 40 50 TIME (SEC) 60 70
1389-2.5 G07
IR = 0.9A
UW
Temperature Drift
2.0
Reverse Voltage Change vs Current
3.0 2.0 1.0 0 -1.0 - 2.0 - 3.0 - 4.0 - 40 -20 0 20 40 60 80 IR = 0.9A IR = 250A
1.6 - 40C 1.2
0.8 25C 0.4 85C 0 0.001
TEMPERATURE (C)
1389-2.5 TA02
0.1 1 0.01 REVERSE CURRENT (A)
10
1389-2.5 G03
Dynamic Impedance vs Frequency
1.0 TA = 25C 0.9 0.8 10 IR = 0.9A COUT = 0F 1 0.7 0.6 0.5 0.4 0.3 0.2 0.1 10
1389-2.5 G05
Forward Characteristics
TA = 25C
IR = 0.9A COUT = 0.033F IR = 10A COUT = 0.22F
0.1 IR = 10A COUT = 0F 0.01 0.01
0.1 1 FREQUENCY (kHz)
0 0.001
0.01 0.1 1 10 FORWARD CURRENT (mA)
100
1389-1.25 G06
Response Time
3V 2V 1V 0V 5V 0V IR = 0.9A COUT = 0F 1ms/DIV
1389-2.5 G08
Response Time
3V 2V 1V 0V 5V 0V IR = 0.9A COUT = 0.1F 200ms/DIV
1389-2.5 G09
5
LT1389
APPLICATIONS INFORMATION
The reverse characteristics of the LT1389 behave like a resistor in parallel with a Zener diode. This simple, well behaved characteristic is important to the proper operational of circuits like Figure 1. The adjustable output voltage reference depends upon positive feedback from the LT1495's output to start-up and regulate the bias current for the LT1389 Board leakage is a concern for a nanopower precision shunt voltage reference. The LT1389 requires attention to detail in board layout in order to maximize its performance. 1.5G of leakage between a DNC pin and a 5V supply will conduct 2.5nA which induces a 0.2% error in VOUT. Board leakage can be minimized by encircling the DNC pins with a guard ring operated at a potential of VOUT. By tying the guard ring to VOUT as shown in Figure 2, leakage paths are eliminated.
- 1.25V V RB = OUT 0.8A LT1389-1.25
Figure 1. Adjustable Output Voltage Reference
DNC DNC DNC GND
Figure 2. Guard Ring to Reduce Board Leakage
6
U
W
U
U
VIN 10.5V
+
LT1495 VOUT 1.5V TO 10V R1 249k TO 8.66M R2 1.24M
1389 F01
-
BOARD METAL TRACE 1 2 LT1389 3 4 6 5 VOUT GND
1389 F02
8 7
DNC DNC
LT1389
TYPICAL APPLICATIONS
2.5V Output, Low Noise Reference
1F VIN 3V 10k
ZTX214C
510k 10k 1k
1/2 LT1495
LT1495
2.5V
+
100k 20F*
+
LT1389-2.5 20F* *WET SLUG TANTALUM
IOUT = 1A R1 TO R3: MAR5 SERIES, IRC (512) 992-7900
1389 TA04
PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 7 6 5
0.228 - 0.244 (5.791 - 6.197)
1 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP 0.053 - 0.069 (1.346 - 1.752)
2
3
0.016 - 0.050 0.406 - 1.270
0.014 - 0.019 (0.355 - 0.483)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
-
+
U
U
Micropower Voltage and Current Reference
2 AAA ALKALINE CELLS
R3 249k 0.1%
R4 300k 5%
+
1/2 LT1495
+
-
-
R1 200k 0.1% R2 1M 0.1%
LT1389-1.25
COM
VOUT = 1.5V
1389 TA03
0.150 - 0.157** (3.810 - 3.988)
4
0.004 - 0.010 (0.101 - 0.254)
0.050 (1.270) TYP
SO8 0996
7
LT1389
TYPICAL APPLICATIONS
Single Cell Li-Ion Battery Supervisory Circuit, IQ = 10A
OFF VBAT 1.75V RS 620k 5% CHARGER SW T0 LOAD
+
A1 1/4 LT1496
-
R1 500k 0.1%
1.25V R2 1.25M 0.1%
-
R4 1.25M 0.1%
LT1389-1.25
D1, D2: 1N458 R1 TO R4: CAR6 SERIES IRC (512) 992-7900
Precision Undervoltage Lockout Circuit
VBATT R1 1.5M 5% R2 2.1M 0.1% SW1 Si3441DV
+
U1 LT1495
BATTERY LT1389-1.25 R3 1.5M 0.1% SW2 VN2222 GND R4 6.65M 1%
-
1389 TA06
R2, R3: IRC CAR6 SERIES (512) 992-7900 U1: 1.5A DUAL PRECISION RAIL-TO-RAIL OP AMP
RELATED PARTS
PART NUMBER LTC(R)1440 LT1460 LT1495 LTC1540 LT1634 DESCRIPTION Micropower Comparator with Reference Micropower Series Reference 1.5A Precision Rail-to-Rail Dual Op Amp Nanopower Comparator with Reference Micropower Precision Shunt Voltage Reference COMMENTS 3.7A Max Supply Current, 1% 1.182V Reference, MSOP, PDIP and SO-8 Packages 0.075% Max, 10ppm/C Max Drift, 2.5V, 5V and 10V Versions, MSOP, PDIP, SO-8, SOT-23 and TO-92 Packages 1.5A Max Supply Current, 100pA Max IOS 600nA Max Supply Current, 2% 1.182V Reference, MSOP and SO-8 Packages 0.05% Max, 10ppm/C Max Drift, 1.25V, 2.5V, 4.096V, 5V, 10A Maximum Supply Current
1389F LT/TP 1198 4K * PRINTED IN USA
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
+
-
+
-
U
A2 1/4 LT1496
RH1 10M 5% D1 RH2 10M 5% D2
R3 1.75M 0.1%
RSW 1M 5% BATTERY
A
VBAT
+
A3 1/4 LT1496
A4 1/4 LT1496
1389 TA05
TO LOAD 1A
RSW 1M 5%
(c) LINEAR TECHNOLOGY CORPORATION 1998

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