Packaged in a 5 x 6mm DSO-8, 1EDL8011 includes a charge-pump to drive the gate of the external high-side n-channel mosfet that does the switching.
There are actually two charge pumps: a high-capacity on using the external capacitor for quick mosfet turn on, and a lower power pump with an internal capacitor that takes over to sustain the gate voltage.
Several aspects of operation depend on characteristics of the external mosfet.
For example, switch-on in-rush control is through a resistor in series with the mosfet gate (see diagram) that works with gate capacitance to slow mosfet turn-on.
By putting a diode across that resistor (not shown), very fast switch-off can be obtained (without compromising slow turn-on) as the gate driver can sink up to 1A.
The mosfet’s internal Rds(on) is important because the IC uses the mosfet drain-source to sense over-current conditions. If such an over-current condition lasts longer than an adjustable period, the mosfet is automatically turned off. Period adjustment is though two resistors and a capacitor connected to the logic input pin, using an ingenious if complex circuit inside the IC – it is worth five minutes with the data sheet if you are interested.
As well as the Vds, the current trip point is programmed by an external resistor that (not shown in diagram) has a current proportional to Vds passed though it.
The voltage this resistors is available to external microcontrollers at all times as a measure of current flow through the mosfet.
The same over-current detection blanking time is used to ride through start-up surges.
Operation is over supply rails between 8V and 125V, although the rising under-voltage lock-out threshold is 10V so it won’t start below that.
Off-state quiescent consumption is impressive: typically below 350nA at maximum voltage and maximum temperature (1μA max at 25°C). Typical operating current is 2.7mA (5mA max) at 25°C.
There is a lot going on inside this chip. Either read about us in the 1EDL8011 data sheet, or see it demosntrated at the company’s own OktoberTech 2024 in Silicon Valley (17 October).
