CMOS compatible input open load detection and turn off state to open the load detection short -circuit load protection owed voltage and overvoltage to prevent the backup current reverse battery protection with very low ground loss

Description

] VN820

VN820SP

ground.

Active VCC pins voltage pliers protection equipment Anti -low energy peak value (see ISO7637 transient compatibility table). Higher current limits are combined with heat shutdown and automatic re -activation of protection equipment to prevent overload.

The device detects the open load state, and both are turned on and off. The output was detected in the short -circuit state of VCC. The device is automatically closed to prevent the pins of the ground.

Switch time waveform

The open load detection of the open state in the disconnect state The detection requires an external pull output pin and a resistor (RPU) positive power supply voltage (VPU), such as the previous+5V cable to provide microprocessors.

The external resistance must be according to the following requirements:

When the load is connected, there is no error load instruction: in this case, we must avoid higher than Volmin; this will lead to the following situation vout (VPU/ (RL+RPU)) RL Lt; Volmin. There is no error check when the load is disconnected: If the VOUT must be higher than Volmax, then the result is RPU LT; (VPU -Volmax)/IL (closed 2) under the following conditions.

If the VOUT is pulled, the IS (closed) may significantly increase (high number of mia), and the pull -up resistor RPU should be connected to the power supply, when the module is in a standby state.

Reverse battery

Solution 1: The resistor (only RGND) in the ground wire. This can be used for any type of load.

HereBlind.

1) maximum value of RGND ≤ 600mv/(opening).

2) RGND ≥ (-vcc)/(-IGND), the -IGND is the DC reverse ground pins current, and the data table of the absolute maximum rated value of the device can be located.

Power consumption in RGND (when VCC LT; 0: Inverse battery condition) is: PD (-VCC) 2/RGND resistor can be in several different high-speed rails. Please note that the value of this resistance should be calculated in formula (1), where the IS (on) MAX becomes the sum of the maximum general state current

device.

Please note that if the microprocessor ground is not shared with the device, the RGND will generate a displacement (IS (on) Max*RGND) and the status output value in the input threshold. This change will be different depends on many devices in several cases

High -sides drive the same RGND.

If the calculated power consumption causes a large resistor or several devices must share a resistor

ST is recommended to use solution 2 (see below).

Solution 2: The diode (DGND) in the ground line.

The resistance (RGND 1KΩ) should drive the sensor load with the DGND device.

This small signal diode can be in several different HSDs. In this case, the ground network will be grounded and the device is not common in the input threshold and state output value microprocessor. If there is a high -speed driving gear, this gear will not change the same diode/resistor network with the same sharing.

The load load protection If the load storage peak voltage exceeds the maximum DC fixed value of the VCC. This is also applicable to the device on the VCC line than ISO T/R 7637/1.

μC I/O Protection:

If you use the ground protection network and the negative VCC online, the control pin will be denied. ST is recommended to insert a resistor (RPROT) to prevent the μC I/O pin locking.

The values of these resistors are the number of HSD I/O (input -level compatibility) μC I/O with locking limits.

-vccpeak/Ilatchup≤Rprot≤ (VOHMC-VIH-VGND)/IIHMAX