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LTC1258 Series Micropower Low Dropout References
FEATURES
s s s s s s s s
DESCRIPTIO
200mV Max Dropout at 10mA Output Current 4A Typical Quiescent Current 0.15% Max Initial Accuracy (S8) No Output Capacitor Required Output Sources 10mA, Sinks 2mA 40ppm/C Max Drift (S8) Available in Small MSOP Package Voltage Options: 2.5V, 3V, 4.1V, 5V and Adjustable
The LTC(R)1258/LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5 are micropower bandgap references that combine high accuracy and low drift with very low supply current and small package size. The combination of ultralow quiescent current and low dropout voltage of only 200mV max. makes them ideal for battery-powered equipment. The output voltage is set by an external resistor divider for the adjustable LTC1258. This series of references uses curvature compensation to obtain low temperature coefficient and trimmed thin-film resistors to achieve high output accuracy. These references can source up to 10mA and sink up to 2mA, making them ideal for precision regulator applications. They are stable without an output bypass capacitor, but are also stable with capacitance up to 1F. This feature is important in critical applications where PC board space is a premium and fast settling is demanded. The LTC1258 series references provide power dissipation advantages over shunt references. In addition to supply current, shunt references must also idle the entire load current to operate.
APPLICATIO S
s s s s
Battery-Powered Systems Handheld Instruments Precision Power Supplies A/D and D/A Converters
, LTC and LT are registered trademarks of Linear Technology Corporation.
The LTC1258 series is available in the 8-pin MSOP and SO packages.
TYPICAL APPLICATION
LTC1258-2.5 Temperature Drift 2.5V Battery-Powered Reference
REFERENCE VOLTAGE CHANGE (mV) 4 3 2 1 0 -1 -2 -3 -4 -40 -20 0 20 40 60 TEMPERATURE (C) 80 100
LTC1258-2.5 2.7V TO 12.6V 2 0.1F GND
1258 TA01
IN
OUT
1
2.5V
4
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1258 TA02
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1
LTC1258 Series
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage ........................................................ 13V Input Voltages ........................................... -0.3V to 13V Output Voltages ......................................... -0.3V to 13V Output Short Circuit Duration .......................... Indefinite
PACKAGE/ORDER INFORMATION
TOP VIEW OUT IN **DNC/FB GND 1 2 3 4 8 7 6 5 DNC* DNC* DNC* DNC*
ORDER PART NUMBER LTC1258CMS8 LTC1258CMS8-2.5 LTC1258CMS8-3 LTC1258CMS8-4.1 LTC1258CMS8-5 MS8 PART MARKING LTEL LTCF LTEU LTEN LTEM
OUT 1 IN 2 **DNC/FB 3 GND 4
MS8 PACKAGE 8-LEAD PLASTIC MSOP
* CONNECTED INTERNALLY. DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS ** DNC FOR LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5, FB FOR LTC1258
TJMAX = 125C, JA = 250C/W
Consult factory for Industrial and Military grade parts.
AVAILABLE OPTIO S
OUTPUT VOLTAGE (V) 2.5 2.5 3 3 4.096 4.096 5 5 Adjustable Adjustable TEMPERATURE RANGE (C) 0 to 70 0 to 70 0 to 70 0 to 70 0 to 70 0 to 70 0 to 70 0 to 70 0 to 70 0 to 70 ACCURACY (%) 0.15 0.21 0.15 0.20 0.15 0.18 0.15 0.18 0.4 0.46 TEMPERATURE COEFFICIENT (ppm/C) 40 60 40 60 40 60 40 60 40 60 PACKAGE TYPE S8 ORDER NUMBER LTC1258CS8-2.5 LTC1258CS8-3 LTC1258CS8-4.1 LTC1258CS8-5 LTC1258CS8 PART MARKING 12582 LTC1258CMS8-2.5 12583 LTC1258CMS8-3 125841 LTC1258CMS8-4.1 12585 LTC1258CMS8-5 1258 LTC1258CMS8 LTEL LTEM LTEN LTEU LTCF MS8 ORDER NUMBER PART MARKING
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Operating Temperature Range (Note 2) - 40C to 100C Specified Temperature Range ...................... 0C to 70C Storage Temperature Range (Note 3) ....-65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
TOP VIEW 8 7 6 5 DNC* DNC* DNC* DNC*
ORDER PART NUMBER LTC1258CS8 LTC1258CS8-2.5 LTC1258CS8-3 LTC1258CS8-4.1 LTC1258CS8-5 S8 PART MARKING
S8 PACKAGE 8-LEAD PLASTIC SO
* CONNECTED INTERNALLY. DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS ** DNC FOR LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5, FB FOR LTC1258
TJMAX = 125C, JA = 190C/W
1258 12582 12583 125841 12585
LTC1258 Series
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the specified temperature range, otherwise specifications are TA = 25C. VIN = VOUT(NOMINAL) + 0.2V, IOUT = 0mA, FB = OUT for the LTC1258 unless otherwise noted.
SYMBOL VIN IIN VOUT PARAMETER Input Voltage Range Input Current Output Voltage (Note 4) CONDITIONS
q
MIN
TYP
FB = OUT for LTC1258
q
en TC VOUT/VIN VOUT/IOUT
Output Voltage Noise (Note 5) Output Voltage Temp Coefficient (Note 6) Line Regulation Load Regulation (Note 7)
LTC1258 (S8), FB = OUT LTC1258-2.5 (S8) LTC1258-3 (S8) LTC1258-4.1 (S8) LTC1258-5 (S8) LTC1258 (MS8), FB = OUT LTC1258-2.5 (MS8) LTC1258-3 (MS8) LTC1258-4.1 (MS8) LTC1258-5 (MS8) 0.1Hz f 10Hz TMIN TJ TMAX (S8) TMIN TJ TMAX (MS8) VIN = (VOUT(NOMINAL) + 0.2V) to 12.6V Sourcing 0mA to 10mA Sinking 0mA to 2mA VOUT Shorted to GND VOUT Shorted to VIN IOUT = 0, VOUT 0.1% IOUT = 10mA, VOUT 0.1% T = -40C to 85C T = 0C to 70C LTC1258, OUT = FB
2.3755 2.4963 2.9955 4.090 4.9925 2.374 2.4948 2.994 4.0885 4.991
q q q q q
2.385 2.5 3 4.096 5 2.385 2.5 3 4.096 5 8 15 30 0.1 1.75
MAX 12.6 6.5 8.5 2.3945 2.5037 3.0045 4.102 5.0075 2.396 2.5052 3.006 4.1035 5.009 40 60 90 0.3 4.0 6.5
ISC VDO VHYST IFB
Short-Circuit Output Current Dropout Voltage (Note 8) Output Hysteresis (Note 9) FB Pin Input Current
20 2
q q
40 4 100 200 200 50 10
UNITS V A A V V V V V V V V V V ppmP-P ppm/C ppm/C ppm/V mV/mA mV/mA mV/mA mA mA mV mV ppm ppm nA
Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The LTC1258 is guaranteed functional over the operating temperature range of -40C to 100C. Note 3: If the part is stored outside of the specified operating temperature range, the output may shift due to hysteresis. Note 4: ESD (Electrostatic Discharge) sensitive device. Extensive use of ESD protection devices are used internal to the LTC1258, however, high electrostatic discharge can damage or degrade the device. Use proper ESD handling precautions. Note 5: Peak-to-peak noise is measured with a single pole highpass filter at 0.1Hz and 2-pole lowpass filter at 10Hz.
Note 6: Temperature coefficient is the change in output voltage divided by the nominal output voltage divided by the specified temperature range. Note 7: Load regulation is measured on a pulse basis from no load to the specified load current. Output changes due to die temperature change must be taken into account separately. Note 8: Dropout voltage is (VIN - VOUT) when VOUT falls to 0.1% below its nominal value at VIN = VOUT + 0.5V. Note 9: Hysteresis in output voltage is created by package stress that differs depending on whether the IC was previously at a higher or lower temperature. Output voltage is always measured at 25C, but the IC is cycled hot or cold before successive measurements. Hysteresis is not normally a problem for operational temperature excursions where the instrument might be stored at high or low temperature.
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LTC1258 Series TYPICAL PERFORMANCE CHARACTERISTICS
LTC1258-2.5* Dropout Voltage vs Output Source Current
100 90
DROPOUT VOLTAGE (mV)
OUTPUT SHORT-CIRCUIT CURRENT (mA)
TA = 25C
80 70 60 50 40 30 20 10 0 0 1 10 0.1 OUTPUT SOURCE CURRENT (mA) 100
1258 G01
INPUT CURRENT (A)
LTC1258-2.5* Output Short-Circuit Current vs Input Voltage
25 OUTPUT SHORT-CIRCUIT CURRENT (mA) OUTPUT SHORT-CIRCUIT CURRENT (mA) TA = 25C OUTPUT SHORTED TO VIN 42
VOUT FROM NO LOAD (mV)
20
15
10
5
0 2 4 6 8 10 INPUT VOLTAGE (V) 12 14
1258-G04
LTC1258-2.5 Output Voltage vs Input Voltage
2.5010 TA = 25C 7
OUTPUT VOLTAGE (V)
2.5005
INPUT CURRENT (A)
2.5000
2.4995
2
4
6 8 10 INPUT VOLTAGE (V)
*Similar performance characteristics can be expected for all voltage options.
4
UW
LTC1258-2.5* Input Current vs Temperature
8 VIN = 2.7V 7 6 5 4 3 2 1 0 -50 -25 0 25 50 75 100 125 150 TEMPERATURE (C)
1258 G02
LTC1258 Series Output Short-Circuit Current vs Temperature
70 60 50 40 30 20 10 5 0 -50 -25 0 OUTPUT SHORTED TO VIN 25 50 75 100 125 150 TEMPERATURE (C)
1258 G03
TA = 25C VIN = VOUT(NOM) + 0.2V
OUTPUT SHORTED TO GND
LTC1258-2.5* Output Short-Circuit Current vs Input Voltage
5 4 3 2 1 0 -1 -2 -3 -4 12 14
1258-G05
LTC1258 Series Load Regulation
TA = 25C VIN = VOUT(NOM) + 0.2V SINKING
SOURCING
TA = 25C OUTPUT SHORTED TO GND 41 2 4 6 8 10 INPUT VOLTAGE (V)
-5
0
1 10 0.1 OUTPUT CURRENT (mA)
100
1258 G06
LTC1258-2.5 Input Current vs Input Voltage
TA = 25C
6
5
12
14
1258 G07
4
2
4
6 8 10 INPUT VOLTAGE (V)
12
14
1258 G08
LTC1258 Series TYPICAL PERFORMANCE CHARACTERISTICS
LTC1258-2.5 PSRR vs Frequency
60
POWER SUPPLY REJECTION RATIO (dB)
VIN = 2.7V 50 40 30 20 10 0
5V/DIV
10
1k 100 FREQUENCY (Hz)
PIN FUNCTIONS
OUT (Pin 1): Reference Output. The output can source up to 10mA and sink up to 2mA. It is stable with output bypass capacitor ranging from 0F to 1F. IN (Pin 2): Positive Supply. Bypassing with a 0.1F capacitor is recommended if the output loading changes. (VOUT + 0.2V) VIN 12.6V. DNC (Pin 3): (LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5) Do Not Connect. Connected internally for post package trim. This pin must be left unconnected. FB (Pin 3): (LT1258) Resistor Divider Feedback Pin. Connect a resistor divider from OUT to GND and the center tap to FB. This pin sets the output potential. R1 + R2 VOUT = 2.385V ; R1 is connected from OUT R2 to FB and R2 from FB to GND. GND (Pin 4): Negative Supply or Ground Connection. DNC (Pins 5, 6, 7, 8): Do Not Connect. Connected internally for post package trim. These pins must be left unconnected.
BLOCK DIAGRAM
UW
LTC1258-2.5 0.1Hz to 10Hz Noise
VIN = 2.7V
10k
1258 G09
1SEC/DIV
1258 G10
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2 IN
+
OUT 1
2.385V
-
R1 FB 3 (LTC1258) R2
GND 4
1258 BD
NOTE: R1 AND R2 ARE NOT CONNECTED FOR LTC1258
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LTC1258 Series
APPLICATIONS INFORMATION
Longer Battery Life Series references have an advantage over shunt style references. To operate, shunt references require a resistor between the power supply and the output. This resistor must be chosen to supply the maximum current that is demanded by the circuit being regulated. When the circuit being controlled is not operating at this maximum current, the shunt reference must always sink this current, resulting in high power dissipation and short battery life. The LTC1258 series low dropout references do not require a current setting resistor and can operate with any supply voltage from (VOUT(NOMINAL) + 0.2V) to 12.6V. When the circuitry being regulated does not demand current, the LTC1258 series reduces its dissipation and battery life is extended. If the reference is not delivering load current it dissipates only 10.8W when operating on a 2.7V supply for LTC1258-2.5, yet the same connection can deliver 10mA of load current when demanded. Output Bypass Capacitor The LTC1258 series is designed to be stable with or without capacitive loads. With no capacitive load, the reference is ideal for fast settling applications, or where PC board space is at a premium. In applications with significant output loading changes, an output bypass capacitor of up to 1F can be used to improve the output transient response. Figure 1 shows the response of the reference to a 1mA to 0A load step with a 1F output capacitor. If more than 1F of output capacitance is required, a resistor in series with the capacitor is recommended to reduce the output ringing. Figure 2 illustrates the use of a damping resistor for capacitive loads greater than 1F. Figure 3 shows the resistor and capacitor values required to achieve critical damping.
RESISTOR VALUE ()
1mA IOUT 0mA VOUT 100mV/DIV
10ms/DIV
1258 F01a
Figure 1. Reference Output Load Transient Response, 1F Output Capacitor
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LTC1258-5 5.2V TO 12.6V 0.1F 2 IN GND 4 OUT 1 5V COUT >1F DAMPING RESISTOR <1k
1258 F02
Figure 2. Adding a Damping Resistor with Output Capacitors Greater Than 1F
10k
1k
100
10 1 10 100 OUTPUT CAPACITOR VALUE (F) 1000
1258 F03
Figure 3. Damping Resistance vs Output Capacitor Value
1mA IOUT 0mA VOUT 100mV/DIV
0.5ms/DIV
1258 F01b
LTC1258 Series
APPLICATIONS INFORMATION
Internal P-Channel Pass Transistor The LTC1258 series features an internal P-channel MOSFET pass transistor. This provides several advantages over similar designs using a PNP bipolar pass transistor. These references consume only 4A of quiescent current under light and heavy loads as well as in dropout; whereas, PNP-based references waste considerable amounts of current when the pass transistor is saturated. In addition, the LTC1258 series provides a lower dropout voltage (200mV max) than PNP-based references.
PACKAGE DESCRIPTION
Dimenshions in inches (millimeters) unless otherwise noted.
0.040 0.006 (1.02 0.15) 0.007 (0.18) 0.021 0.006 (0.53 0.015) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 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) 8 0.004 - 0.010 (0.101 - 0.254) 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157** (3.810 - 3.988) 7 6 5
0.014 - 0.019 (0.355 - 0.483) TYP *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
0.016 - 0.050 (0.406 - 1.270)
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.
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MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 0.004* (3.00 0.102)
0.034 0.004 (0.86 0.102)
8
76
5
0.006 0.004 (0.15 0.102)
0.193 0.006 (4.90 0.15)
0.118 0.004** (3.00 0.102)
1
23
4
MSOP (MS8) 1098
0.050 (1.270) BSC
1
2
3
4
SO8 1298
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LTC1258 Series
TYPICAL APPLICATIONS
Micropower Low Dropout Negative Reference Supply Splitter
2 IN 1 8 1 0.1F OUT LTC1258-3 GND 4 VOUT = - 3V
1258 TA03
2
- +
1/2 LTC1542 3 4
VSS = - 4V
ANALOG INPUT 0V TO 3V RANGE
RELATED PARTS
PART NUMBER LT 1389 LT1634 LT1460 LTC1440 LTC1540
(R)
DESCRIPTION Nanopower Precision Shunt Voltage Reference Micropower Precision Shunt Voltage Reference Micropower Series Reference Micropower Comparator with Reference Nanopower Comparator with Reference
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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0.2V VCC 8.5V
LTC1258-2.5 VCC = 5V 2 0.1F GND 4 IN OUT 1 2.5V VIRTUAL 0.1F GROUND
1258 TA04
Low Power, Low Voltage Supply Reference for LTC1096L
1 CS/ VCC 2 SHDN +IN CLK LTC1096L 3 -IN DOUT 4 GND VREF
8 7 6 5
1F
MPU SERIAL DATA LINK (MICROWIRETM AND SPI COMPATIBLE)
SERIAL DATA LINK
1 OUT 4 GND LTC1258-3 IN 2 VIN 3.2V TO 0.1F 12.6V
1258 TA05
MICROWIRE is a trademark of National Semiconductor Corp.
COMMENTS 800nA Quiescent Current, 0.05% Max, 10ppm/C Max Drift, 1.25V and 2.5V Versions, SO-8 Package 0.05% Max, 25ppm/C Max Drift, 1.25V, 2.5V, 4.096V and 5V Outputs 0.075% Max, 10ppm/C Max Drift, 2.5V, 5V and 10V Outputs 3.7A Max ICC, 1% 1.182V Reference, Adjustable Hysteresis 600nA Max ICC, 2% 1.182V Reference, Adjustable Hysteresis
1258f LT/TP 0999 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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