LTM4622 datasheet(11/24 Pages) AD

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LTM4663

Rev. A

For more information www.analog.com

4663 F05

ILIM

VREF

COOLING

RCB

RCT

249k

SW OPEN = ILIM_HEAT

SW CLOSED = ILIM_COOL

TEC CURRENT

LIMIT

VDD

40µA

ITEC

Figure 5. TEC Current Limit Setting

APPLICATIONS INFORMATION

MAXIMUM TEC CURRENT LIMIT

The maximum current of the TEC driver in the LTM4663

can be programmed individually by applying a resistor

divider RCT/RCB between VREF and GNDA.

As shown in Figure 5, the internal current sink circuitry

connected to ILIM draws a 40µA current when the LTM4663

drives the TEC in a cooling direction, which allows a high

cooling current. The current sink is not active when the

TEC is driven in a heating direction.

Table 3. Example of Typical TEC Current Limit Setting

TOP RESISTOR RCT

(kΩ)

BOTTOM RESISTOR RCB

(kΩ)

TEC CURRENT LIMIT

(COOLING MODE)

(A)

TEC CURRENT LIMIT

(HEATING MODE)

(A)

OPEN

49.9

1.5

–1.5

316

43.2

1.2

–1.2

140

37.4

–1

63.4

0.7

–0.7

38.3

21.5

0.5

–0.5

The maximum TEC current limit in the heating mode can

be calculated as:

ILIM_HEAT =

1.25V – 2.5V •

RCB

RCT / /249k+RCB

0.535

The maximum TEC current limit in the cooling mode can

be calculated as:

ILIM_COOL =

2.5V •

RCB

RCT / /249k+RCB

+ 40µA •

RCT / /249k •RCB

RCT / /249k+RCB

–1.25V

0.535

See Table 3 for the list of Typical TEC Current Limit

settings.

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