Rainbow Electronics MAX3301E - Manual (Page 23)

MAX3301E
USB On-the-Go Transceiver and Charge Pump
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BIT NUMBER SYMBOL OPERATION
VALUE AT
POWER-UP
0 speed
S et to 0 for l ow - sp eed ( 1.5M b p s) m od e. S et to 1 for ful l - sp eed ( 12M b p s) m od e. Thi s
b i t chang es the d ata r ate onl y i f sp d _susp _ctl = 1 i n sp eci al - functi on r eg i ster 1.
0
1 suspend
Set to 0 for normal operating mode. Set to 1 for suspend mode. This bit changes
the operating mode only if spd_susp_ctl = 1 in sp eci al - functi on r eg i ster 1.
0
2 dat_se0 Set to 0 for VP_VM USB mode. Set to 1 for DAT_SE0 USB mode. 0
3 — Not used. 0
4 bdis_acon_en
Enables the transceiver (when configured as an A device) to connect its pullup
resistor if the B device disconnect is detected during HNP. Set to 0 to disable this
feature. Set to 1 to enable this feature.
0
5 oe_int_en
Set to 0 to disable the interrupt output circuitry of OE/INT. Set to 1 to enable the
interrupt output circuitry of OE/INT.
0
6 uart_en
Set to 0 to disable UART mode. Set to 1 to enable UART mode. This bit overrides
the settings of dminus_dir, dplus_dir, and gp_en bits.
0
7 — Not used. 0
Table 7. Control Register 1 Description (Write to Address 04h to Set, Write to Address
05h to Clear)
BIT NUMBER SYMBOL OPERATION
VALUE AT
POWER-UP
0 dp_pullup S et to 0 to d i sconnect the p ul lup resi stor to D+ . Set to 1 to connect the pul l up r esi stor to D +. 0
1 dm_pullup S et to 0 to d i sconnect the p ul l up r esi stor to D - . S et to 1 to connect the p ul l up r esi stor to D - . 0
2 dp_pulldown
Set to 0 to disconnect the pulldown resistor to D+. Set to 1 to connect the pulldown
resistor to D+.
1
3 dm_pulldown
Set to 0 to disconnect the pulldown resistor to D-. Set to 1 to connect the pulldown
resistor to D-.
1
4 id_pulldown Set to 0 to allow ID_IN to float. Set to 1 to connect ID_IN to GND. 0
5 vbus_drv S et to 0 to tur n V B U S off. S et to 1 to d r i ve V B U S thr oug h a l ow i m p ed ance ( see N ote 8) . 0
6 vbus_dischrg
Set to 0 to disconnect the V BUS discharge resistor. Set to 1 to connect the V BUS
discharge resistor (see Note 8).
0
7 vbus_chrg
Set to 0 to disconnect the V BUS charge resistor. Set to 1 to connect the V BUS
charge resistor (see Note 8).
0
Table 8. Control Register 2 Description (Write to Address 06h to Set, Write to Address
07h to Clear)
Note 8: To prevent a high-current state where the transceiver is both sourcing current to VBUS and sinking current from VBUS, the fol-
lowing logic is used to set bits 5, 6, and 7 of control register 2:
• Setting vbus_drv clears vbus_dischrg and vbus_chrg
• Setting vbus_dischrg clears vbus_drv and vbus_chrg, unless vbus_drv is set with the same command, in which case vbus_drv
clears the other bits
• Setting vbus_chrg clears vbus_drv and vbus_dischrg, unless either of these bits are set with the same command, as shown in Table 9