What is DPInst?
DPInst (Driver Package Installer) is a driver installer supplied by Microsoft. It is the recommended way to create driver installers for Silabs drivers.
For any DIFx-compliant driver package (including the output of the AN220 Driver Customization Wizard, found here www.silabs.com/interface-appnotes), the DPInst installer executable can simply be dropped into the driver package and an INI file created to customize the installer behavior.
The behavior of the DPInst installer can be configured though either command line switches or through an INI file. These facilities can be used to do things like suppress the installer dialog box (quiet install), forcing install of older versions, and controlling the uninstall behavior.
Complete Information about DPInst can be found in MSDN here: http://msdn.microsoft.com/en-us/library/ff544842(v=vs.85).aspx
Documentation on the command line can be found here: http://msdn.microsoft.com/en-us/library/ff544775.aspx
Documentation on the descriptor file can be found here: http://msdn.microsoft.com/en-us/library/ff553560(v=vs.85).aspx
As with all Microsoft products, support for DPInst can be obtained by emailing firstname.lastname@example.org.
C8051F9xx low-power devices with an on-chip DC-DC converter (DC0) have internal protection circuitry that should automatically limit the peak inductor current.
According to the DC0 datasheet documentation:
The dc-dc converter has a built in voltage reference and oscillator, and will automatically limit or turn off the switching activity in case the peak inductor current rises beyond a safe limit or the output voltage rises above the programmed target value. This allows the dc-dc converter output to be safely overdriven by a secondary power source (when available) in order to preserve battery life. The dc-dc converter’s settings can be modified using SFR registers which provide the ability to change the target output voltage, oscillator frequency or source, Diode Bypass switch resistance, peak inductor current, and minimum duty cycle.
However, under certain conditions, the inductor current is not safely limited allowing the device to pull essentially unlimited current through the DCEN pin and inductor. The battery is essentially grounded, which in many cases causes the battery output voltage to drop to near 0 V.
Overdriving DC+ to a voltage above the DC0 output voltage, such as 3.3 V, when VBAT is under VPOR, recovery from brownout (VBAT rising), or 0.95 V, causes the system to draw a tremendous amount of current from the VBAT supply. This high current state is not cleared until the next POR.
If the battery supply is set to 0.95 V (1.0 V to be safe), the system powers up. The IMEASURE current is near 2-3 mA. After the part has started running, overdrive the DC+ pin to 3.3 V. The IMEASURE current drops to near 0 mA. Everything appears normal.
If the battery supply is under 0.95 V, sometimes the current from the battery supply will hit the current limit (200 mA) and stay that way. The only way to lower the current is to perform a POR by disconnecting the DC+ supply and disconnecting the VBAT supply. The system will still run with just the DC+ supply with the VBAT supply removed. This seems to indicate that even if the battery could supply the peak current, the DC0 module is stuck in such a state that the VBAT pin is always shorted to ground until the next POR.
The order in which the device is powered up with VBAT and DC+ affects the max current draw from VBAT:
Based on this information, it's not safe to power up the system at low VBAT voltages with the DC+ pin overdriven. The only safe way to power up the system is to disconnect DC+ from the device until VBAT is at least 1.0V. Once the system starts up, then connect DC+.