LTC2995C データシートの表示（PDF） - Linear Technology

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LTC2995C

Temperature Sensor and Dual Voltage Monitor with Alert Outputs

Linear Technology 

LTC2995

PIN FUNCTIONS

D+: Diode Sense Current Source. D+ sources the remote

diode sensing current. Connect D+ to the anode of the re-

mote sensor device. It is recommended to connect a 470pF

bypass capacitor between D+ and D–. Larger capacitors

may cause settling time errors (see Typical Performance

Characteristics). If D+ is tied to VCC, the LTC2995 measures

the internal sensor temperature. Tie D+ to VCC if unused.

D–: Diode Sense Current Sink. Connect D– to the cathode

of the remote sensor device. Tie D– to GND for single

wire remote temperature measurement (see Applications

Information) or internal temperature sensing.

DS: Diode Select Input. Three state pin that selects tem-

perature sensor location. Tie DS to VCC to monitor the

temperature of the internal diode or to GND to monitor the

temperature of the external diode. When DS is left uncon-

nected, the LTC2995 monitors both sensors alternately.

If D+ is tied to VCC, the LTC2995 measures the internal

sensor temperature regardless of the state of DS.

Exposed Pad: Exposed pad may be left open or soldered

to GND for better thermal coupling.

GND: Device Ground

OV: Overvoltage Logic Output. Open drain logic output

that pulls to GND when either the voltage at VL1 or VL2

is above 0.5V. Held low for a programmable delay time

set by the capacitor connected to pin TMR. OV has a weak

400kΩ pull-up to VCC and may be pulled above VCC using

an external pull-up. Leave OV open if unused.

PS: Polarity Select Input. Selects the polarity of tempera-

ture thresholds VT1 and VT2. Connect PS to VCC to config-

ure VT1 as undertemperature and VT2 as overtemperature

threshold. Leave PS unconnected to configure both VT1

and VT2 as overtemperature thresholds. Connect PS to

GND to configure both VT1 and VT2 as undertemperature

thresholds. Tie to VCC if temperature thresholds are unused.

TMR: Reset Delay Timer. Attach an external capacitor

(CTMR) to GND to set the delay time until alerts on TO1,

TO2, UV and OV are reset. Leaving the pin open generates

a minimum delay of 500μs. Capacitance on this pin adds

an additional 8ms/nF reset delay time. Tie TMR to VCC to

bypass the timer.

TO1: Temperature Logic Output 1. Open drain logic output

that pulls to GND when VPTAT crosses the threshold voltage

on pin VT1 with a polarity set by the PS pin (see Table 3

in Applications Information). When VPTAT crosses the

threshold voltage on pin VT1 with opposite polarity, an

additional hysteresis of 20mV is required to release TO1

high after a delay adjustable by the capacitor on TMR. TO1

has a weak 400kΩ pull-up to VCC and may be pulled above

VCC using an external pull-up. Leave TO1 open if unused.

TO2: Temperature Logic Output 2. Open drain logic output

that pulls to GND when VPTAT crosses the threshold voltage

on pin VT2 with a polarity set by the PS pin (see Table 3

in Applications Information). When VPTAT crosses the

threshold voltage on pin VT2 with opposite polarity, an

additional hysteresis of 20mV is required to release TO2

high after a delay adjustable by the capacitor on TMR. TO2

has a weak 400kΩ pull-up to VCC and may be pulled above

VCC using an external pull-up. Leave TO2 open if unused.

UV: Undervoltage Logic Output. Open drain logic output

that pulls to GND when either the voltage at VH1 or VH2

is below 0.5V. Held low for an adjustable delay time set

by the capacitor connected to pin TMR. UV has a weak

400kΩ pull-up to VCC and may be pulled above VCC using

an external pull-up. Leave pin open if unused.

VCC: Supply Voltage. Bypass this pin to GND with a 0.1μF

(or greater) capacitor. VCC operating range is 2.25V to 5.5V.

VH1, VH2: Voltage High Inputs 1 and 2. When the voltage

on either pin is below 0.5V, an undervoltage condition is

triggered. Tie pin to VCC if unused.

VL1, VL2: Voltage Low Inputs 1 and 2. When the voltage

on either pin is above 0.5V, an overvoltage condition is

triggered. Tie pin to GND if unused.

VPTAT: Proportional to Absolute Temperature Voltage

Output. The voltage on this pin is proportional to the

selected sensor’s absolute temperature. An internal or

external sensor is chosen with the DS pin. VPTAT can

drive up to ±200μA of load current and up to 1000pF of

capacitive load. For larger load capacitances insert a 1k

2995f

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