LTC2965

13

2965fc

For more information www.linear.com/LTC2965

TYPICAL APPLICATIONS

Negative Voltage Monitor with Output Level Shift

Figure 9 illustrates an LTC2965 configured to monitor a

–15V supply with a level-shifted output to a 5V supply. Q1

buffers the digital input of the 5V system from the –15V

supply and prevents UV from going below GND. The

OUT pin drives the base of Q1 through a resistor network

comprised of R3 and R4. Keep R4/R3 ≥0.4 to ensure

there is proper base current to pull UV to ground. If an

exposed pad is present it should be tied to the LTC2965

GND pin or left open.

Current Sink/Source

The LTC2965 can be used as a high voltage current source

or a current sink as shown in Figure 10. The current is

bias current of the part adds a small error term. Part of

the bias current is the internal resistive divider which is

approximately 78MΩ with the RS pin configured to 10x.

Figure 9. Negative Voltage Monitor with Output Level Shift to a 5V Digital Input

Figure 10. LTC2965 Configured as High Voltage Current Source

RS

PS

GND

LTC2965

REF

INH

OUT

INL

R2

976k

–15V

2965 F09

R3

1M

UV

5V

DIGITAL

INPUT

Q1

MMBT2907

FAIRCHILD

R5

200k

R4

510k

R1

1.43M

RISING THRESHOLD

FALLING THRESHOLD

HYSTERESIS

RANGE SETTING

–15V MONITOR WITH LEVEL SHIFT

–14.5V

–14.2V

–0.3V

10X

GND

REF

RS

INH

OPEN

INL

2.4k

OUT

PS

LTC2965

LOAD

Current Sink

REF

2965 F10

INH

OPEN

INL

2.4k

OUT

LOAD

Current Source

LTC2965

GND

RS

PS