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TPL7407L

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SLRS066D – JANUARY 2014 – REVISED MARCH 2016

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Typical Application (continued)

8.2.1.1 Design Requirements

For this design example, use the parameters listed in Table 1 as the input parameters.

Table 1. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

GPIO Voltage

1.8 V, 3.3 V or 5.0 V

Coil Supply Voltage

8.5 V to 40 V

Number of Channels

7

Output Current (RCOIL)

20 mA to 300 mA per channel

CCOM

0.1 µF

Duty Cycle

100%

8.2.1.2 Detailed Design Procedure

When using TPL7407L in a coil driving application, determine the following:

•

Input Voltage Range

•

Temperature Range

•

Output & Drive Current

•

Power Dissipation

8.2.1.2.1

TTL and other Logic Inputs

TPL7407L input interface is specified for standard 1.8 V through 5 V CMOS logic interface and can tolerate up to

30 V. At any input voltage the output drivers will be driven at it's maximum when Vcom is greater than or equal to

8.5 V.

8.2.1.2.2

Input RC Snubber

TPL7407L features an input RC snubber that helps prevent spurious switching in noisy environments. Connect

an external 1 k

Ω to 5 kΩ resistor in series with the input to further enhance TPL7407L’s noise tolerance.

8.2.1.2.3

High-impedance Input Drivers

TPL7407L features a 1-M

Ω input pull-down resistor. The presence of this resistor allows the input drivers to be

tri-stated. When a high-impedance driver is connected to a channel input the TPL7407L detects the channel

input as a low level input and remains in the OFF position. The input RC snubber helps improve noise tolerance

when input drivers are in the high-impedance state.

8.2.1.2.4

Drive Current

The coil current is determined by the coil voltage (VSUP), coil resistance & output low voltage (VOL).

ICOIL= (VSUP - VOL)/RCOIL

(1)

8.2.1.2.5

Output Low Voltage

The output low voltage (VOL) is drain to source (VDS) voltage of the output NMOS transistors when the input is

driven high and it is sinking current and can be determined by Specifications or Figure 1.

8.2.1.3 Application Curves

The following curve was generated with TPL7407L driving an OMRON G5NB relay -- Vin = 5.0 V; Vsup = 24 V &

RCOIL = 2.8 kΩ