ISD-200 Datasheet, PDF (41/64 Pages) List of Unclassifed Manufacturers – USB Mass Storage Class Bulk-Only Specification Compliant

ISD-200 ASIC Datasheet
Selectable Device Power Configurations
The ISD-200 is capable of offering three types of system power configurations.
• Self-Powered – Current is not taken from USB
• Bus-Powered – Current is taken from USB
• Dynamically-powered – Current may be taken from USB
The ISD-200 may be configured to operate from different power sources dynamically depending
upon the presence of external (NOT USB) power. Power source configuration is accomplished by
controlling the BUS_POWER input pin accompanied by the appropriate ISD-200 configuration
and USB Descriptor settings. NPWR100 and NPWR500 are also used to control power
consumption as described in the previous sub-section.
Self-Powered Example
The BUS_POWER pin is de-asserted.
ISD-200 Configuration:
Configuration 2 Present = 0
Report One Configuration = 0
Device Descriptor:
bNumConfigurations = 1
Configuration Descriptor:
bConfigurationValue1 = 1
iConfiguration1 = 3
bMaxPower1 = Required USB current limited to under 100 mA (May need to use
NPWR500 to satisfy USB suspend current requirements if any current is drawn)
iInterface1 = 4
bConfigurationValue2 = N/A
iConfiguration2 = N/A
bMaxPower2 = N/A
iInterface2 = N/A
Bus-Powered Example
The BUS_POWER pin is asserted. (See Errata #6)
ISD-200 Configuration:
Configuration 2 Present = 0
Report One Configuration = 0
Device Descriptor:
bNumConfigurations = 1
Configuration Descriptor:
bConfigurationValue1 = 1
iConfiguration1 = 3
bMaxPower1 = Required USB current limited to under 500 mA (May need to use
NPWR500 to satisfy USB suspend and pre-configuration current requirements)
iInterface1 = 4
bConfigurationValue2 = N/A
iConfiguration2 = N/A
bMaxPower2 = N/A
iInterface2 = N/A
Dynamically-Powered Example
The BUS_POWER pin is asserted to indicate the absence of external power and de-asserted to
indicate the presence of external power. (See Errata #6)
ISD-200 Configuration (See Table 3):
‘Configuration 2 Present’ = 1
‘Report One Configuration’ = Pick either 0 or 1 depending on host software and desired
results (See Tables 3 and 8).
In-System Design Confidential
39