LT6376 datasheet(21/30 Pages) LINER

21 / 30 page

LT6376

6376f

For more information www.linear.com/LT6376

APPLICATIONS INFORMATION

Example: An LT6376 in a DFN package mounted on a PC

board has a thermal resistance of 43°C/W. Operating on

±25V supplies and driving a 2.5kΩ load to 12.5V with

V+IN = 230V and DIV = 10.3, the total power dissipation

is given by:

PD = (50 • 0.6mA) + 12.52/2.5k + 2302/84.17k

+ (228.75 – 230/10.3)2/76k

+ (230/10.3)2/8.26k + (230/10.3

– 12.5)2/760k = 1.342W

Assuming a thermal resistance of 43°C/W, the die tem-

perature will experience a 57.7°C rise above ambient.

This implies that the maximum ambient temperature the

LT6376 should operate under the above conditions is:

TA =150°C – 57.7°C = 92.3°C

Keep in mind that the DFN package has an exposed pad

which can be used to lower the qJA of the package. The

more PCB metal connected to the exposed pad, the lower

the thermal resistance.

The MSOP package has no exposed pad and a higher

thermal resistance (qJA = 130°C/W). It should not be used

in applications which have a high ambient temperature,

require driving a heavy load, or require an extreme input

voltage.

THERMAL SHUTDOWN

For safety, the LT6376 will enter shutdown mode when

the die temperature rises to approximately 163°C. This

thermal shutdown has approximately 9°C of hysteresis

requiring the die temperature to cool 9°C before enabling

the amplifier again.

USE AT OTHER PRECISION DC GAINS

The array of resistors within the LT6376 provides numer-

ous configurable connections that provide precision gains

other than the G = 10 differential gain options described

previously. Note that only the +IN and –IN pins can oper-

ate outside of the supply window. Since most of these

alternate configurations involve driving the REFx pins, as

well as the +IN and –IN pins, the input signals must be less

than the supply voltages. Fully differential gains are avail-

able as shown in Table 9, and may be output-shifted with a

REF offset signal. These configurations allow the LT6376

to be used as a versatile precision gain block with essen-

tially no external components besides the supply decou-

pling. In most cases, only a single positive supply will be

required. In Table 9, connections are identified as NC (no

connect), INPUT (refers to both inputs driven, +signal to

+pins,–signal to –pins), CROSS (refers to inputs cross-

coupled, +signal to –pins, –signal to +pins), OUT (refers

to the output fed back to –pins), or REF (refers to con-

necting the REF pin to +pins). The same configurations

provide inverting gains by grounding any pins intended

for the +signal source. The differential input resistance is

also tabulated as well as the amplification factor of the

internal gain section involved (noise-gain, which helps to

estimate the error-budget of the configuration).

Single-ended noninverting gains are also available as

shown in Table 10, including many that operate as buf-

fers (loaded only by the op amp input bias). A rich option

set exists by using the REF pin as an additional variable.

In Table 10, connections are identified as NC (no con-

nect), INPUT (driven by the input), OUT (fed back from the

output), or GROUND (grounded). Table 10 also includes

tabulations of the internal resistor divider (DIV), noise

gain (re-amplification), and the input loading presented

by the circuit.

USE AS PRECISION AC GAIN BLOCK

In AC-coupled applications operating from a single power

supply, it is useful to set the output voltage near mid-

supply to maximize dynamic range. The LT6376 readily

supports this with no additional biasing components by

connecting specific pins to the V+ and V– potentials and

AC-coupling the signal paths. Table 11 shows the available

inverting gains and also tabulates the load resistances

presented at the input. In Table 11, connections are identi-

fied as NC (no connect), AC IN (AC-coupled to the input)

OUT (fed back from the output), tied to V+, tied to V–,

or AC GND (AC- grounded). All pins that require an AC

ground can share a single bypass capacitor. Likewise, all

pins driven from the source signal may share a coupling

capacitor as well. The output should also connect to the

load circuitry using a coupling capacitor to block the mid-

supply DC voltage.

LT6376 Datasheet(PDF) 21 Page - Linear Technology

LT6376 Datasheet(HTML) 21 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Datasheet Download

Link URL