I’m using the HIP4081A for motor control and the app note for this IC is AN9405.
On the 1st page of this app note it states that this IC is a better solution when needing an optoisolator or transformer. How did they arrive at this assumption? Does this IC have a built-in optoisolator?
Need to know, as I would really like the isolation of inductive transients NOT to cross into the digital circuitry area.
Note that Intersil got bought out by Renessas, and I emailed that company in Japan about this already, but no response from them.
Deep Thanks to anyone that can answer this.
Frank, 301.933.6333


The portion of AN9405 I understand to be referenced is excerpted below. From a direct reading, the assertion being made is not that the part is “better”, but rather “more cost effective” than alternative design approaches in the cited contexts of automotive applications and those powered by supplies falling within SELV limits. Such claims have their basis in marketing efforts and such, should be interpreted as a statement of perspective or potential, rather than fact.


As with similar products, the HIP4081 contains circuitry for translating logic-level control inputs into drive signals for FETs in an H-bridge configuration; such devices as a class provide the high-pulse current capability to charge and discharge gate capacitances, re-reference high-side drive signals to the source terminals of the high-side FETs, make provision for developing a drive voltage that exceeds the source being switched in order to use N-channel devices as high-side switches, and provide shoot-through protection.

Devices of this type typically do not include galvanic isolation, and the HIP408x devices are no exception; evidence of this can be seen in the device’s having a single Vss pin, to which both the control inputs and driven outputs are referenced.

As for avoiding coupling of transients from a switched load into low-level control circuitry, non-isolated devices of this type do generally present a greater risk of such than design approaches in which power and control domains are galvanically isolated. It is possible to achieve a quiet or noisy result using either approach however, depending on how attentive one is to potential coupling mechanisms when developing the physical circuit. On that front, staying mindful of where current is flowing in the return path network (“ground”) is probably the matter of greatest impotrance.