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ZHCSIV2C September 2018 – September 2019 ISO1500

PRODUCTION DATA.

8.4 Device Functional Modes

Table 2 shows the driver functional modes.

Table 2. Driver Functional Table⁽¹⁾

V_CC1	V_CC2	INPUT D	DRIVER ENABLE DE	OUTPUTS
V_CC1	V_CC2	INPUT D	DRIVER ENABLE DE	A	B
PU	PU	H	H	H	L
		L	H	L	H
		X	L	Hi-Z	Hi-Z
		X	Open	Hi-Z	Hi-Z
		Open	H	H	L
PD⁽²⁾	PU	X	X	Hi-Z	Hi-Z
X	PD	X	X	Hi-Z	Hi-Z

(1) PU = Powered Up; PD = Powered Down; H = High Level; L = Low level; X = Irrelevant, Hi-Z = High impedance state

(2) A strongly driven input signal can weakly power the floating V_CC1 through an internal protection diode and cause an undetermined output.

When the driver enable pin, DE, is logic high, the differential outputs, A and B, follow the logic states at data input, D. A logic high at the D input causes the A output to go high and the B output to go low. Therefore the differential output voltage defined by Equation 1 is positive.

Equation 1. V_OD = V_A – V_B

A logic low at the D input causes the B output to go high and the A output to go low. Therefore the differential output voltage defined by Equation 1 is negative. A logic low at the DE input causes both outputs to go to the high-impedance (Hi-Z) state. The logic state at the D pin is irrelevant when the DE input is logic low. The DE pin has an internal pulldown resistor to ground. The driver is disabled (bus outputs are in the Hi-Z) by default when the DE pin is left open. The D pin has an internal pullup resistor. The A output goes high and the B output goes low when the D pin is left open while the driver enabled.

Table 3 shows the receiver functional modes.

Table 3. Receiver Functional Table⁽¹⁾

V_CC1	V_CC2	DIFFERENTIAL INPUT	RECEIVER ENABLE RE	OUTPUT R
		V_ID = V_A – V_B
PU	PU	–0.02 V ≤ V_ID	L	H
		–0.2 V < V_ID < 0.02 V	L	Indeterminate
		V_ID≤ –0.2 V	L	L
		X	H	Hi-Z
		X	Open	Hi-Z
		Open, Short, Idle	L	H
PD⁽²⁾	PU	X	X	Hi-Z
PU	PD	X	L	H
PD⁽²⁾	PD	X	X	Hi-Z

(1) PU = Powered Up; PD = Powered Down; H = Logic High; L= Logic Low; X = Irrelevant, Hi-Z = High Impedance (OFF) state

(2) A strongly driven input signal can weakly power the floating V_CC1 through an internal protection diode and cause an undetermined output.

The receiver is enabled when the receiver enable pin, RE, is logic low. The receiver output, R, goes high when the differential input voltage defined by Equation 2 is greater than the positive input threshold, V_TH+.

Equation 2. V_ID = V_A – V_B

The receiver output, R, goes low when the differential input voltage defined by Equation 2 is less than the negative input threshold, V_TH–. If the V_ID voltage is between the V_TH+ and V_TH– thresholds, the output is indeterminate. The receiver output is in the Hi-Z state and the magnitude and polarity of V_ID are irrelevant when the RE pin is logic high or left open. The internal biasing of the receiver inputs causes the output to go to a failsafe-high when the transceiver is disconnected from the bus (open-circuit), the bus lines are shorted to one another (short-circuit), or the bus is not actively driven (idle bus).

8.4 Device Functional Modes

Table 2. Driver Functional Table(1)

Table 3. Receiver Functional Table(1)

Table 2. Driver Functional Table⁽¹⁾

Table 3. Receiver Functional Table⁽¹⁾