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LTC2960

2960f

TYPICAL APPLICATION

FEATURES DESCRIPTION

36V Nano-Current

Two Input Voltage Monitor

The LTC

2960 is a nano-current, high voltage two input

voltage monitor, ideally suited for multicell battery ap-

plications. External resistive dividers configure custom

comparator thresholds. The supervisory circuit monitors

the ADJ input and pulls the RST output low when the input

drops below threshold. A reset timeout period delays the

return of the RST output to a high state when the input

rises above the threshold. The spare comparator allows

voltage conditions to be detected with either a non-inverting

input, IN

(LTC2960-1/LTC2960-3) or an inverting input,

–

(LTC2960-2/LTC2960-4). A manual reset (MR) input

is provided for external activation of the reset output.

Other options provided on the LTC2960-1/LTC2960-2 in-

clude a reset timeout period select pin, RT, to select between

15ms or 200ms reset timeout periods. The LTC2960-3/

LTC2960-4 have a fixed 200ms reset timeout period. The

RST and OUT outputs are available with active pull-up cir-

cuits to an output logic supply pin (LTC2960-3/LTC2960-4)

or 36V open-drain outputs (LTC2960-1/LTC2960-2).

Battery and Regulator Monitor Supply Current vs Supply Voltage

APPLICATIONS

850nA Quiescent Current

Operating Range: 2.5V < V

< 36V

1.5% (Max) Accuracy Over Temperature

Adjustable Reset Threshold

Wide Temperature Range (–40°C to 125°C)

Adjustable IN

/IN

–

Threshold

Manual Reset Input

Compact 2mm × 2mm 8-lead DFN and

TSOT-23 (ThinSOT™) Packages

Portable Equipment

Battery Powered Equipment

Security Systems

Automotive Systems

L, LT, LTC, 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.

LTC2960 Option Table

Option Inputs Reset Timeout Period Output Type

LTC2960-1 ADJ/IN

15ms/200ms 36V Open-Drain

LTC2960-2 ADJ/IN

–

15ms/200ms 36V Open-Drain

LTC2960-3 ADJ/IN

200ms Active Pull-up

LTC2960-4 ADJ/IN

–

200ms Active Pull-up

GND

RST

OUT

ADJMR

LTC2960-3

LTC3632

DC/DC

GND

Li-Ion

4.2V

Li-Ion

4.2V

0.1μF

50V

1μF

6.04M

402k

6V < V

< 8.4V

1.3M

402k

OUT

1.8V

RESET

LOW BATTERY

POWER-FAIL FALLING THRESHOLD = 6.410V

RESET FALLING THRESHOLD = 1.693V

2960 TA01

(V)

(nA)

900

600

300

1200

4032816

2960 TA01a

MR=5V, 27C

Summary of content (16 pages)

PAGE 1
LTC2960 36V Nano-Current Two Input Voltage Monitor FEATURES DESCRIPTION n The LTC®2960 is a nano-current, high voltage two input voltage monitor, ideally suited for multicell battery applications. External resistive dividers configure custom comparator thresholds. The supervisory circuit monitors the ADJ input and pulls the RST output low when the input drops below threshold. A reset timeout period delays the return of the RST output to a high state when the input rises above the threshold.
PAGE 2
LTC2960 ABSOLUTE MAXIMUM RATINGS (Notes 1 & 2) Input Voltages VCC , RT, MR .......................................... –0.3V to 40V DVCC ........................................................ –0.3V to 6V ADJ, IN+, IN–......................................... –0.3V to 3.5V Output Voltages (LTC2960-1/LTC2960-2) RST, OUT ............................................... –0.3V to 40V Output Voltages (LTC2960-3/LTC2960-4) RST, OUT (DVCC ≥ 1.6V) ......... –0.3V to (DVCC + 0.3V) RST, OUT (DVCC = GND) .............
PAGE 3
LTC2960 ORDER INFORMATION Lead Free Finish TAPE AND REEL (MINI) TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2960CTS8-1#TRMPBF LTC2960CTS8-1#TRPBF LTFZY 8-Lead Plastic TSOT-23 0°C to 70°C LTC2960ITS8-1#TRMPBF LTC2960ITS8-1#TRPBF LTFZY 8-Lead Plastic TSOT-23 –40°C to 85°C LTC2960HTS8-1#TRMPBF LTC2960HTS8-1#TRPBF LTFZY 8-Lead Plastic TSOT-23 –40°C to 125°C LTC2960CTS8-2#TRMPBF LTC2960CTS8-2#TRPBF LTGBB 8-Lead Plastic TSOT-23 0°C to 70°C LTC2960ITS8-2#TRMPBF LTC2
PAGE 4
LTC2960 ELECTRICAL CHARACTERISTICS The l denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VCC = 7V, DVCC = 3.3V unless otherwise noted (Note 2). SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS CONTROL INPUTS: MR, RT VRT Control Input Threshold RT l 0.4 1.4 VMR Control Input Threshold MR l 0.4 1.
PAGE 5
LTC2960 TYPICAL PERFORMANCE CHARACTERISTICS MR Rising Threshold/Open Voltage vs VCC Normalized Reset Timeout Period vs Temperature 1.9 1.4 MR INPUT THRESHOLD 27°C 0.9 3.0 3.5 4.0 VCC (V) 4.5 1.1 1.0 0.9 3.0 2.0 1.0 0.8 0.7 –50 5.0 ADJ/IN+/IN– VCC = 7V 1.2 –25 0 25 50 75 TEMPERATURE (°C) 100 2960 G04 0.0 0.1 125 1 10 COMPARATOR OVERDRIVE (%) 2960 G05 ADJ, IN+, IN– Threshold vs Temperature 100 2960 G06 Voltage Output HIGH vs Pull-Down Current (RST/OUT) 430 3.5 V+ HYS 3.
PAGE 6
LTC2960 PIN FUNCTIONS ADJ: Reset Threshold Adjustment Input. Tie to resistive divider to configure desired reset threshold. DVCC: (LTC2960-3/LTC2960-4) Logic Supply Input. Used for setting the logic swing of the RST and OUT outputs. Useful for interfacing with logic voltages different from VCC. Bypass DVCC with 0.1μF to GND. Grounding DVCC allows OUT and RST to act as open drain outputs. Exposed Pad (DFN Only): Exposed pad may be left floating or connected to device ground. GND: Device ground.
PAGE 7
LTC2960 BLOCK DIAGRAM VCC 400mV REFERENCE REGULATOR RT LTC2960-1/LTC2960-2 DVCC LTC2960-3/LTC2960-4 0.4V 1μA MR RST ADJ – RESET DELAY + 0.
PAGE 8
LTC2960 APPLICATIONS INFORMATION VOLTAGE MONITORING THRESHOLD CONFIGURATION The LTC2960 is a voltage supervisor with a wide operating voltage range up to 36V with only 850nA quiescent current. The supervisor has two outputs, RST and OUT that provide voltage monitoring capabilities for system power-up, power-down and brown-out conditions. Built-in hysteresis and a reset timeout period ensure that fluctuations due to load transients or supply noise do not cause chattering of the status outputs.
PAGE 9
LTC2960 APPLICATIONS INFORMATION The closest 1% resistor value is 34k. R3 is easily obtained from: R3 = RSUM – R1 – R2 = 8M – 499k – 34k R3 = 7.467MΩ The closest 1% resistor value is 7.5MΩ. Plugging the standard values back into the equations yields the design values for the falling reset and IN+ voltages: to a user defined voltage up to 36V with a resistor. The open-drain pull-up voltage may be greater than VCC. Select a resistor compatible with desired output rise time and load current specifications.
PAGE 10
LTC2960 APPLICATIONS INFORMATION provide effective pull-down without excessively loading the pull-up circuitry. A 100k resistor from output to ground is satisfactory for most applications. When the status outputs are high, power is dissipated in the pull-down resistors. If VCC falls below the falling UVLO threshold, the outputs are pulled to ground. The outputs are guaranteed to stay low for VCC ≥ 1.2V regardless of the output logic configuration. When VCC < 1.
PAGE 11
LTC2960 APPLICATIONS INFORMATION VA VB LTC2960-3 R4 681k DVCC IN+ R5 48.7k The falling threshold can be restored to the original value by reducing the value of R5. Under the assumption that the addition of R6 has a negligible impact on the rising threshold, a new R4/R5 ratio can be calculated as shown: R4 VR 6.6V = – 1= – 1= 14.71 + R5 VTH + V HYS 420mV ( OUT R6 6.81M 2960 F06 Figure 6. External Hysteresis ) Given the ratio of R4/R5, the closest 1% resistor value for R5 is 46.4k.
PAGE 12
LTC2960 APPLICATIONS INFORMATION When a supply voltage is abruptly connected to the input resonant ringing can occur as a result of series inductance. The peak voltage could rise to 2x the input supply but in practice can reach 2.5x if a capacitor with a strong voltage coefficient is present. If a 12V supply is hot plugged the resulting ringing could reach the abs max of VCC. Any circuit with an input of more than 7V should be scrutinized for ringing.
PAGE 13
LTC2960 TYPICAL APPLICATIONS BUCK CONVERTER VBAT 6V TO 8.4V Li-Ion 4.2V Li-Ion 4.2V VIN R5 10M R2 6.04M + NOT ALL LT3991 COMPONENTS SHOWN LT3991 + R1 402k IN+ ADJ MR RST RESD* 10k C2 47μF 16V EN VCC RT OUT LTC2960-1 C1 0.1μF 25V VOUT 3.3V VOUT GND R4 2.26M RESET GND R3 402k 2960 F09 UVLO FALLING THRESHOLD = 6.410V RESET FALLING THRESHOLD = 2.649V R6 1M *OPTIONAL RESISTOR FOR ADDED ESD PROTECTION Figure 9. Configurable Regulator UVLO and Supervisor M2 Si4435 VBAT 6V TO 8.
PAGE 14
LTC2960 TYPICAL APPLICATIONS The LTC2960-2 in Figure 10 is yet another way to prevent excessive discharge of a battery. The high voltage OUT output is used to drive the gate of a PMOS switch to interrupt the path to VOUT in the event of an undervoltage condition. When the battery stack voltage is above the IN– rising threshold of 5.972V, the PMOS switch is turned on. The LTC2960-2 also supervises VOUT to provide a low battery signal as an early warning of impending shutdown.
PAGE 15
LTC2960 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DC8 Package 8-Lead Plastic DFN (2mm × 2mm) (Reference LTC DWG # 05-08-1719 Rev A) R = 0.05 TYP 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 0.64 ±0.05 (2 SIDES) PACKAGE OUTLINE 2.00 ±0.10 (4 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) R = 0.115 TYP 5 8 0.40 ±0.10 0.64 ±0.10 (2 SIDES) PIN 1 NOTCH R = 0.20 OR 0.25 × 45° CHAMFER (DC8) DFN 0409 REVA 4 0.25 ±0.05 0.45 BSC 1 0.23 ±0.05 0.
PAGE 16
LTC2960 TYPICAL APPLICATION BUCK CONVERTER NOT ALL LT3991 COMPONENTS SHOWN VIN 6.6V < VIN < 36V R3 10M R2 6.04M LTC2960-1 VCC C1 0.1μF 25V U1 R1 402k LT3991 EN GND OUT ADJ IN+ RST MR 5V OUTPUT VOUT R5 3.48M C2 47μF 16V R6 1M 15ms DELAY OUT LT3009-1.8 SHDN GND R4 402k RT GND 1.8V OUTPUT IN C3 1μF 10V R8 1.3M R9 1M LTC2960-1 VCC RT ADJ U2 IN+ OUT RST VIN SUPPLY UVLO = 6.410V 1.8V SUPPLY UVLO = 3.863V RESET THRESHOLD = 1.693V 200ms DELAY RST MR R7 402k GND 2960 F14 Figure 13.