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LTC2912

2912fb

For more information www.linear.com/LTC2912

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Single UV/OV

Voltage Monitor

The LTC

2912 voltage monitor is designed to detect power

supply undervoltage and overvoltage events. The VL and

VH monitor inputs include filtering to reject brief glitches,

thereby ensuring reliable reset operation without false or

noisy triggering. An adjustable timer defines the duration

of the overvoltage and undervoltage reset outputs which

function independently. While the LTC2912 operates

directly from 2.3V to 6V supplies, an internal V

shunt

regulator coupled with low supply current demand allows

operation from higher voltages such as 12V, 24V or 48V.

Three output configurations are available: the LTC2912‑1

has a latch control for the OV output; the LTC2912‑2

has an OV and UV output disable feature for margining

applications; the LTC2912‑3 is identical to the LTC2912‑1

but with a noninverting, OV output.

The LTC2912 provides a precise, versatile, space‑conscious

micropower solution for voltage monitoring.

Monitors Single Voltage

Adjustable UV and OV Trip Values

Guaranteed Threshold Accuracy: ±1.5%

Power Supply Glitch Immunity

Adjustable Reset Timeout with Timeout Disable

29µA Quiescent Current

Open‑Drain OV and UV Outputs

Guaranteed OV and UV for V

≥ 1V

Available in 8‑Lead ThinSOT

and (3mm × 2mm)

DFN Packages

Desktop and Notebook Computers

Network Servers

Core, I/O Voltage Monitors

Single OV/UV Supply Monitor, 3.3V ±10% Tolerance Reset Time-Out Period vs Capacitance

27.4k

GND TMR

SYSTEM

POWER

SUPPLY

2912 TA01a

LATCH

22nF

TIMEOUT = 200ms

4.53k

LTC2912-1

0.1µF

3.3V

TMR PIN CAPACITANCE, C

TMR

(nF)

UV/OV TIMEOUT PERIOD, t

UOTO

(ms)

100

1000

10000

0.1 10 100 1000

2912 G08

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

ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners.

Summary of content (14 pages)

PAGE 1
LTC2912 Single UV/OV Voltage Monitor FEATURES n n n n n n n n n DESCRIPTION Monitors Single Voltage Adjustable UV and OV Trip Values Guaranteed Threshold Accuracy: ±1.
PAGE 2
LTC2912 ABSOLUTE MAXIMUM RATINGS (Note 1) Terminal Voltages VCC (Note 3).............................................. –0.3V to 6V OV, UV, OV.............................................. –0.3V to 16V TMR...........................................–0.3V to (VCC + 0.3V) VH, VL, LATCH, DIS................................–0.3V to 7.5V Terminal Currents IVCC.....................................................................10mA IUV, IOV, IOV.........................................................
PAGE 3
LTC2912 ORDER INFORMATION Lead Free Finish TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2912CTS8-1#TRMPBF LTC2912CTS8-1#TRPBF LTCJW 8-Lead Plastic TSOT-23 0°C to 70°C LTC2912ITS8-1#TRMPBF LTCJW 8-Lead Plastic TSOT-23 –40°C to 85°C LTC2912HTS8-1#TRMPBF LTC2912HTS8-1#TRPBF LTCJW 8-Lead Plastic TSOT-23 –40°C to 125°C LTC2912ITS8-1#TRPBF LTC2912CDDB-1#TRMPBF LTC2912CDDB-1#TRPBF LCJZ 8-Lead (3mm × 2mm) Plastic DFN 0°C to 70°C LTC2912IDDB-1#TRMPBF
PAGE 4
LTC2912 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 3.3V, VL = 0.45V, VH = 0.55V, LATCH = VCC unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS VSHUNT VCC Shunt Regulator Voltage ICC = 5mA ICC = 5mA (H-Grade) l l ICC = 2mA to 10mA l MIN TYP MAX 6.2 6.2 6.6 6.6 7.2 7.
PAGE 5
LTC2912 TIMING DIAGRAMS VH Monitor Timing VL Monitor Timing VUOT VH tUOD tUOD tUOTO tUOTO 1V OV 1V UV VUOT VL 2912 TD02 2912 TD01 VH Monitor Timing (TMR Pin Strapped to VCC) VL Monitor Timing (TMR Pin Strapped to VCC) VUOT VH tUOD tUOD tUOD 1V UV VUOT VL tUOD 1V OV 2912 TD03 2912 TD04 TYPICAL PERFORMANCE CHARACTERISTICS Input Threshold Voltage vs Temperature 0.505 40 0.502 VCC = 5V 35 0.501 0.500 0.499 VCC = 3.3V 30 VCC (V) 0.503 ICC (µA) 0.497 VCC = 2.3V 20 0.
PAGE 6
LTC2912 TYPICAL PERFORMANCE CHARACTERISTICS UV VOLTAGE (V) PULL-DOWN CURRENT, IUV (mA) VH = 0.55V SEL = VCC 4 1000 3 2 1 0 5 10000 UV/OV TIMEOUT PERIOD, tUOTO (ms) 5 Reset Time-Out Period vs Capacitance UV Output Voltage vs VCC 1 0 3 4 2 SUPPLY VOLTAGE, VCC (V) 100 10 1 0.1 5 1 10 100 TMR PIN CAPACITANCE, CTMR (nF) 12 25°C UV/OV, VOL (V) 0.8 –40°C 0.6 0.4 0.2 5 10 15 20 IUV/OV (mA) 1 25 30 0 1 3 4 2 SUPPLY VOLTAGE, VCC (V) CTMR = 1nF 11 VL = 0.
PAGE 7
LTC2912 PIN FUNCTIONS (DFN/TSOT Packages) OV (Pin 6/Pin 3, LTC2912-3): Overvoltage Logic Output. Asserts high with a weak internal pull-up to VCC when the VL input is above threshold. Latches high. May be pulled above VCC using an external pull-up. Leave pin open if unused. TMR (Pin 4/Pin 5): Reset Delay Timer. Attach an external capacitor (CTMR) of at least 10pF to GND to set a reset delay time of 9ms/nF. A 1nF capacitor will generate an 8.5ms reset delay time. Tie pin to VCC to bypass timer.
PAGE 8
LTC2912 APPLICATIONS INFORMATION Voltage Monitoring 2. Choose RB to obtain the desired UV trip point The LTC2912 is a low power voltage monitoring circuit with an undervoltage and an overvoltage input. A timeout period that holds OV and UV asserted after a fault has cleared is adjustable using an external capacitor and may be externally disabled.
PAGE 9
LTC2912 APPLICATIONS INFORMATION Power-Up/Power-Down As soon as VCC reaches 1V during power up, the UV output asserts low and the OV output weakly pulls to VCC. The LTC2912 is guaranteed to assert UV low, OV high (LTC2912-1, LTC2912-2) and OV low (LTC2912-3) under conditions of low VCC, down to VCC = 1V. Above VCC = 2V (2.1V maximum), the VH and VL inputs take control. Once the VH input and VCC become valid an internal timer is started. After an adjustable delay time, UV weakly pulls high. ⎛ RC • 0.
PAGE 10
LTC2912 APPLICATIONS INFORMATION When the VH input drops below its designed threshold, the UV pin asserts low. When the input recovers above its designed threshold, the UV output timer starts. If the input remains above the designed threshold when the timer finishes, the UV pin weakly pulls high. However, if the input falls below its designed threshold during this timeout period, the timer resets and restarts when the input is above the designed threshold.
PAGE 11
LTC2912 APPLICATIONS INFORMATION low while the timeout period is active, the OV and OV pins latch as before. The rise time on the UV, OV and 0V pins is limited by a 400k pull-up resistance to VCC. A similar formula estimates the output rise time (10% to 90%) at the UV, OV and OV pins: Disable (LTC2912-2) tRISE ≈ 2.2 • RPU • CLOAD The LTC2912-2 allows disabling the UV and OV outputs via the DIS pin.
PAGE 12
LTC2912 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DDB Package 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 0.61 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 0.56 ±0.05 (2 SIDES) 0.75 ±0.05 0.200 REF 0.50 BSC 2.20 ±0.05 (2 SIDES) 0.40 ±0.10 8 2.00 ±0.10 (2 SIDES) PIN 1 BAR TOP MARK PACKAGE (SEE NOTE 6) OUTLINE 0.25 ±0.05 R = 0.115 TYP 5 R = 0.05 TYP 0 – 0.
PAGE 13
LTC2912 REVISION HISTORY (Revision history begins at Rev B) REV DATE DESCRIPTION PAGE NUMBER B 06/14 Updated Package/Order Information Added OV/OV Output Voltage vs VCC graph 2, 3 6 2912fb 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 representa‑ tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PAGE 14
LTC2912 TYPICAL APPLICATION Single UV/OV Supply Monitor with 3.3V ±10% POWER SUPPLY 12V Q1 3.3V 0.1µF 10k 27.4k VH SYSTEM VCC OV LTC2912-3 1k VL UV 4.53k LATCH GND TMR 2912 TA05 22nF TIMEOUT = 200ms RELATED PARTS PART NUMBER LTC690 LTC694-3.3 LTC699 LTC1232 LTC1326/ LTC1326-2.5 LTC1536 LTC1726-2.5/ LTC1726-5 LTC1728-1.8/ LTC1728-3.3 LTC1985-1.8 LTC2900 DESCRIPTION 5V Supply Monitor, Watchdog Timer and Battery Backup 3.