LT6105 datasheet(18/28 Pages) AD

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LT6119-1/LT6119-2

611912f

For more information www.linear.com/LT6119-1

The SENSELO and SENSEHI range has been designed to

allow the LT6119 to monitor its own supply current (in

additiontotheload),aslongasVSENSEislessthan200mV.

This is shown in Figure 11.

Minimum Output Voltage

The output of the LT6119 current sense amplifier can

produce a non-zero output voltage when the sense voltage

is zero. This is a result of the sense amplifier VOS being

forced across RIN as discussed in the Output Voltage Er-

ror, ∆VOUT(VOS) section. Figure 12 shows the effect of the

input offset voltage on the transfer function for parts at the

VOS limits. With a negative offset voltage, zero input sense

voltage produces an output voltage. With a positive offset

voltage, the output voltage is zero until the input sense

voltage exceeds the input offset voltage. Neglecting VOS,

the output circuit is not limited by saturation of pull-down

circuitry and can reach 0V.

applicaTions inForMaTion

Response Time

The LT6119 amplifier is designed to exhibit fast response

to inputs for the purpose of circuit protection or current

monitoring. This response time will be affected by the

external components in two ways, delay and speed.

If the output current is very low and an input transient

occurs, there may be an increased delay before the

output voltage begins to change. The Typical Performance

Characteristics show that this delay is short and it can

be improved by increasing the minimum output current,

either by increasing RSENSE or decreasing RIN. Note that

the Typical Performance Characteristics are labeled with

respect to the initial sense voltage.

The speed is also affected by the external components.

Using a larger ROUT will decrease the response time, since

VOUT = IOUTA • ZOUT where ZOUT is the parallel combination

Figure 12. Amplifier Output Voltage vs Input Sense Voltage

INPUT SENSE VOLTAGE (µV)

120

100

200

400

600

800

611912 F12

1000

100

300

500

700

900

VOS = –200µV

VOS = 200µV

G = 100

Figure 11. LT6119 Supply Current Monitored with Load

SENSEHI

LT6119

ISENSE

RSENSE

V+

V–

RIN

VBATT

SENSELO

OUTA 8

611912 F11

ROUT

VOUT

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