Datasheet

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LTC15 4 0

1540fb

For more information www.linear.com/LTC1540

TYPICAL APPLICATION

FEATURES DESCRIPTION

Nanopower Comparator

with Reference

APPLICATIONS

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and C-Load

is a trademark of Analog Devices, Inc. All other trademarks are the property of their respective

owners.

Ultralow Quiescent Current: 0.3µA Typ

Reference Output Drives 0.01µF Capacitor

Adjustable Hysteresis

Available in 3mm × 3mm × 0.8mm DFN Package

Wide Supply Range: 2V to 11V

Input Voltage Range Includes the Negative Supply

Reference Output Sources Up to 1mA

TTL/CMOS Compatible Outputs

60µs Propagation Delay with 10mV Overdrive

No Crowbar Current

40mA Continuous Source Current

Pin Compatible with LTC1440, MAX921, MAX931

Battery-Powered System Monitoring

Threshold Detectors

Window Comparators

Oscillator Circuits

The LTC

1540 is an ultralow power, single compara-

tor with built-in reference. The comparator’s features

include less than 0.6µA supply current over the commercial

temperature range, a 1.182V ±

2% reference, program-

mable hysteresis and T

TL/CMOS outputs that sink and

sour

current. The reference output can drive a bypass

capacitor of up to 0.01µF without oscillation.

The comparator operates from a single 2V to 11V supply

or a dual ±1V to ±5.5V supply. Comparator hysteresis is

easily programmed by using two resistors and the HYST

pin. Each comparator’s input operates from the negative

supply to within 1.3V of the positive supply. The compara

tor output stage can continuously source up to 40mA. By

eliminating the cross-conducting current that normally

occur when the comparator changes logic states, power

supply glitches are eliminated.

The L

TC1540 is available in the 8-pin MSOP and SO

packages. For space limited applications, the L

TC1540

is available in a 3mm × 3mm low profile (0.8mm) dual

fine-pitch leadless package (DFN).

Nanopower 2.9V V

Threshold Detector

LTC1540 Supply Current vs Temperature

4.32M

3.3V

–

2 1

GND

OUT

LTC1540

1540 • TA01

–

HYST

REF

–

TEMPERATURE (°C)

–40

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

20 60

1540 • TA02

–20 0

40 80 100

SUPPLY CURRENT (µA)

= 5V

–

= GND = 0V

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Summary of content (14 pages)

PAGE 1
LTC1540 Nanopower Comparator with Reference FEATURES n n n n n n n n n n n n DESCRIPTION Ultralow Quiescent Current: 0.3µA Typ Reference Output Drives 0.01µF Capacitor Adjustable Hysteresis Available in 3mm × 3mm × 0.
PAGE 2
LTC1540 ABSOLUTE MAXIMUM RATINGS (Note 1) Voltage V + to V–, V+ to GND, GND to V – .............12V to –0.3V IN+, IN–, HYST.................... (V+ + 0.3V) to (V– – 0.3V) REF..................................... (V+ + 0.3V) to (V– – 0.3V) OUT................................ (V + + 0.3V) to (GND – 0.3V) Current IN +, IN–, HYST....................................................20mA REF.....................................................................20mA OUT..............................................
PAGE 3
LTC1540 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. V+ = 5V, V– = GND = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 11.0 V 0.3 0.68 0.71 µA µA ±12 ±15 ±16 mV mV mV ±1.0 ±1.0 nA nA V+ – 1.3V V Power Supply V+ Supply Voltage Range ICC Supply Current l IN– – IN+ = 80mV, HYST = REF, C-Grade IN– – IN+ = 80mV, HYST = REF, I-Grade 2.
PAGE 4
LTC1540 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. V+ = 3V, V– = GND = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply V+ ICC Supply Voltage Range Supply Current l IN– – IN + = 80mV, HYST = REF, C-Grade IN – – IN + = 80mV, HYST = REF, I-Grade 2 0.28 l l 11 V 0.61 0.64 µA µA ±12 ±15 ±16 mV mV mV ±1 ±1 nA nA V+ – 1.
PAGE 5
LTC1540 TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs Temperature 0.5 1.190 V + = 5V V – = GND = 0V 0.3 V + = 2V V – = GND = 0V 0.2 0.1 0 – 60 – 40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 8 1.186 7 1.184 1.182 1.180 1.178 2 1 1.
PAGE 6
LTC1540 PIN FUNCTIONS GND (Pin 1): Ground. Connect to V – for single supply operation. V+ (Pin 7): Positive Supply operating voltage is from 2V to 11V. V– (Pin 2): Negative Supply. Potential should be more negative than GND. Connect to ground for single supply operation. OUT (Pin 8): Comparator CMOS Output. Swings from GND to V+. Output can source up to 40mA and sink 5mA. IN+ (Pin 3): Noninverting Comparator Input. Input common mode range from V– to V+ – 1.3V. Input current typically 10pA at 25°C.
PAGE 7
LTC1540 APPLICATIONS INFORMATION REFERENCE OUTPUT 7 REF R1 C1 3 IN + LTC1540 4 5V TO 8V LTC1540 + IN– 8 OUT – V– 1540 • F01 5 HYST R2 10k Figure 1. Damping the Reference Output R3 2.4M 6 REF R1 430Ω 1000 RESISTOR VALUE (kΩ) V+ C1 1µF V– GND 2 1 1540 • F03a 100 Figure 3a. Power Supply Transient Test Circuit 10 1 8V V+ 0.01 0.1 1 CAPACITOR VALUE (µF) 10 1540 • F02 5V 2mV/DIV 0.1 0.001 VREF Figure 2.
PAGE 8
LTC1540 APPLICATIONS INFORMATION Hysteresis Hysteresis can be added to the LTC1540 by connecting a resistor (R1) between the REF and HYST pins and a second resistor (R2) from HYST to V – (Figure 5). 15%. If hysteresis is not wanted, the HYST pin should be shorted to REF. Acceptable values for IREF range from 0.1µA to 5µA. If 2.4M is chosen for R2, then the value of R1 (kΩ) is equal to the value of VHB (mV).
PAGE 9
LTC1540 TYPICAL APPLICATIONS 3.3V Output Low Dropout Linear Regulator The LTC1540 can be connected as a micropower (IQ = 5.5µA at VIN = 5V) low dropout linear regulator (Figure 7). When the output is low, Q1 turns on, allowing current to charge output capacitor C1. Local feedback formed by R4, Q1 and Q2 creates a constant-current source from the 5V input to C1. R4, R1 and Q2’s VBE also provide current limiting in the case of an output short-circuit to ground.
PAGE 10
LTC1540 TYPICAL APPLICATIONS Low-Battery Detect down to a supply voltage of 2V, but it is still functional with the supply as low as 1.6V. Some parameters, such as VREF and VOS, will be degraded on lower supply voltages. The input voltage range extends from 0.9V below the positive supply to the negative supply. Figure 9 shows how to use the LTC1540 for a low-battery detect, drawing only 1.4µA at VBAT = 2V. The circuit is powered by a 2-cell NiCd battery. The VBAT pin could be as low as 1.
PAGE 11
LTC1540 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LTC1540#packaging for the most recent package drawings. DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698 Rev C) R = 0.125 TYP 5 0.40 ±0.10 8 0.70 ±0.05 3.5 ±0.05 1.65 ±0.05 2.10 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ±0.05 3.00 ±0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) 4 0.25 ±0.05 0.75 ±0.05 0.200 REF 0.50 BSC 2.38 ±0.05 1.65 ±0.10 (2 SIDES) 1 (DD8) DFN 0509 REV C 0.50 BSC 2.38 ±0.
PAGE 12
LTC1540 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LTC1540#packaging for the most recent package drawings. S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610 Rev G) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 .010 – .020 × 45° (0.254 – 0.508) NOTE: 1. DIMENSIONS IN 5 .150 – .157 (3.810 – 3.988) NOTE 3 1 RECOMMENDED SOLDER PAD LAYOUT 2 .053 – .069 (1.346 – 1.752) 0°– 8° TYP .016 – .050 (0.406 – 1.
PAGE 13
LTC1540 REVISION HISTORY (Revision history begins at Rev B) REV DATE DESCRIPTION B 08/17 Reformatted Order Information. PAGE NUMBER 2 Added web links. All Pages Add Information for analog devices. All Pages Corrected test conditions for supply current specification (ICC). 3 1540fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 14
LTC1540 TYPICAL APPLICATION RF Field Detector Figure 10 shows the complete circuit for a field detector which was tested at 445MHz. A transmission line is used to match the detector diode (1N5712) to a quarter-wave whip antenna. The 0.23λ wavelength transmission line section transforms the 1pF (350Ω) diode junction capacitance to a virtual short at the base of the antenna. At the same time it converts the received antenna current to a voltage loop at the diode, giving excellent sensitivity.