TH8056 datasheet(21/34 Pages) MELEXIS

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TH8056

Enhanced Single Wire CAN Transceiver

TH8056 – Datasheet

Page 21 of 34

3901008056

June 2012

Rev 014

Assumptions:

VBAT = 26.5V

Rload = 6.49 kΩ

Network with 32 nodes

VCANH = 5.1V

IBAT = 6mA

D = 50%

Ta = 125°C

JA = 70k/W (Thermally enhanced SOIC14 package)

Computations:

Rload_net = 6.49kΩ / 32nodes = 203Ω

Iload = 5.1V / 203Ω = 25mA

Pload = 5.1V * 25mA * 0.5 = 64mW

PINT_a = (26.5V – 5.1V) * 25mA * 0.5 = 267mW

PINT_P = 26.5V * 6mA = 159mW

Ptot = 267mW + 159mW = 426mW

Tj = 125°C + 426mW * 70k/W = 155°C

The above calculation shows that under worst case conditions (max. operating voltage, max bus load, max

ambient temperature) the TH8056 with the thermally enhanced SOIC14 package operates below the thermal

limit. A stable functioning is possible up to these limits.

3.9.1.Thermal behaviour of TH8056 with SOIC8 – TH8056 KDC A8

The thermal impedance of an SOIC8 package is about twice in comparison to the thermally enhanced

SOIC14 package. Therefore the maximum power dissipation within this package is only about the half.

The using of the SOIC8 version of TH8056 depends on the network architecture (number of nodes), the

max. ambient temperature and the needed functionality (using of INH pin).

The following diagram shows the relationship between junction temperature, ambient temperature and

number of nodes, which have to be taken into account for using the SOIC8 version.

TH8056 Datasheet(PDF) 21 Page - Melexis Microelectronic Systems