FN8863 Rev.1.00

Page 19 of 25

Jul 27, 2017

ISL72028ASEH

4. Functional Description

4.5

Low Power Shutdown Mode

When a high level is applied to the RS pin, the device enters Low Power Shutdown mode, in which the driver and

receiver are switched off to conserve power. The bus pins are at Hi-Z and the R pin will be at logic high. In Low

Power Shutdown mode, the transceiver draws 50µA (maximum) of current.

A low level on the RS pin brings the device back to operation.

4.6

Using 3.3V Devices in 5V Systems

Looking at the differential voltage of both the 3.3V and 5V devices, the differential voltage is the same, and the

recessive common-mode output is the same. The dominant common-mode output voltage is slightly lower than that

of the 5V counterparts. The receiver specifications are also the same. Although the electrical parameters appear

compatible, perform necessary system testing to verify interchangeable operation.

4.7

Split Mode Termination

The VREF pin provides a VCC/2 output voltage for Split mode termination. The VREF pin has the same ESD

protection, short-circuit protection, and common-mode operating range as the bus pins.

The Split mode termination technique is shown in Figure 48. .

Split mode termination stabilizes the bus voltage at VCC/2 and prevents it from drifting to a high common-mode

voltage during periods of inactivity. The technique improves the electromagnetic compatibility of a network. The

Split mode termination is put at each end of the bus.

The CL capacitor between the two 60Ω resistors filters unwanted high frequency noise to ground. The resistors

should have a tolerance of 1% or better and the two resistors should be carefully matched to provide the most

effective EMI immunity. A typical value of CL for a high speed CAN network is 4.7nF, which generates a 3dB

point at 1.1Mbps. The capacitance value used is dependent on the signaling rate of the network.

Figure 48. Split Termination

NODE

#1

NODE

#n

CANH

CANL

VREF

VREF

CL

CL

NODE

#2

60Ω

60Ω

60Ω

60Ω