LTC2915 데이터 시트보기 (PDF) - Linear Technology

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LTC2915

Voltage Supervisor with 27 Selectable Thresholds

Linear Technology 

LTC2915/LTC2916

PIN FUNCTIONS (TSOT/DFN)

GND (Pin 4/Pin 1): Device Ground.

MR (Pin 3/Pin 2) (LTC2916 only): Manual Reset Input

(Active Low). A low level on the MR input causes the part

to issue a reset, which is released one reset timeout after

the input goes high. The pin has an internal 100k pull-up

to VCC, and thus may interface directly to a momentary

pushbutton. Leave open if unused.

RST (Pin 5/Pin 8): Open Drain RST Output. Asserts low

when VM is below the threshold selected by SEL1, SEL2

and TOL input pins. Held low for an adjustable timeout

after VM input is above threshold.

RT (Pin 6/Pin 7): Reset Timeout Control Pin. Attach an

external Capacitor (CRT) to GND to set a reset timeout of

9ms/nF. Floating RT generates a reset timeout of approxi-

mately 400μs. Tie RT to VCC to generate a reset timeout

of approximately 200ms.

SEL1, SEL2 (Pins 2, 7/Pins 3, 6): Monitor Voltage Select

Three-State Inputs. SEL1 and SEL2 control the nominal

threshold voltage that VM is set to monitor. Connect to VCC,

GND or leave unconnected in open state. (See Table 1).

TOL (Pin 3/Pin 2) (LTC2915 only): Three-State Input

for Supply Tolerance Selection (–5%, –10% or –15%).

Controls the tolerance band at which the VM supply is

monitored. Connect to VCC, GND, or leave unconnected

in open state. (See Table 2).

VCC (Pin 8/Pin 5): Power Supply Input. Bypass this pin

to ground with a 0.1μF ceramic capacitor. A minimum of

1.5V on VCC ensures that the part is out of under voltage

lockout and that the voltage thresholds are accurate.

Operates as a direct supply input for voltages up to 5.5V.

Operates as a shunt regulator for supply voltages greater

than 5.7V and should have a resistor between this pin and

the supply to limit VCC input current to no greater than

5mA. When used without a current-limiting resistor, pin

voltage must not exceed 5.7V.

VM (Pin 1/Pin 4): Voltage Monitor Input to RST Compara-

tor. SEL1, SEL2 and TOL inputs select the exact threshold

that asserts the RST output.

Exposed Pad (Pin 9, DFN Only): Exposed Pad may be left

open or connected to device ground.

BLOCK DIAGRAM

LTC2915

SEL1 SEL2 TOL

3 STATE

DECODE

VM

MONITOR

DIVIDER

MATRIX

–

+

–+ 0.5V

REFERENCE

DIVIDER

MATRIX

LTC2916

MR

VCC

100k

RT

VCC DETECT

VCC

VCC

6.2V

INTERNAL

200ms TIMER

ADJUSTABLE

RESET TIMER

RST

RESET

DRIVER LOGIC

GND

29156 BD

29156fa

6

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