VN771

The VN771 is a device formed by three monolithic chips housed in a standard SO-28 package: a double high side and two Power MOSFETs. The double high side are made using STMicroelectronics VIPower technology; Power MOSFETs are made by using the new advanced strip lay-out technology This VN771 device is suitable to drive a DC motor in a bridge configuration as well as to be used as a quad switch for any low voltage application. The VN771 dual high side switches have built-in thermal shut-down to protect the chip from over temperature and short circuit,status output to provide indication for open load in off and on state, overtemperature conditions and stuck-on to V_CC.

DUAL HIGH-SIDE SWITCH From the falling edge of the input signal, the status output, initially low to signal a fault condition (overtemperature or open load on-state), will go back to a high state with a different delay in case of overtemperature (tpovl) and in case of open open load (tpol) respectively.This feature of VN771 allows to discriminate the nature of the detected fault. To protect the device against short circuit and over current condition, the thermal protection turns the integrated Power MOS off at a minimum junction temperature of 140 oC. When this temperature returns to 125 oC the switch is automatically turned on again. In short circuit the protection reacts with virtually no delay, the sensor (one for each channel) being located inside each of the two Power MOS areas.
This positioning allows the VN771 device to operate with one channel in automatic thermal cycling and the other one on a normal load. An internal function of the VN771 devices ensures the fast demagnetization of inductive loads with a typical voltage (Vdemag) of -18V. This function allows to greatly reduces the power dissipation according to the formula:P_dem =0.5• L_load • (Iload)² • [(V_CC+Vd_emag)/Vd_emag] • f where f = switching frequency and Vdemag = demagnetization voltage.In this device if the GND pin is disconnected,with V_CC not exceeding 16V, both channel will switch off.

Power MOSFETs During normal operation, the Input pin of VN771 is electrically connected to the gate of the internal power MOSFET. The devices can be used as a switch from DC to very high frequency.