Micrel, Inc.
MIC2555
Control Register 2
set – 06h
clr – 07h
1 Æset = 1
1 Æclr = 0
Set & Clear
dp_pull-up
1
1
1
1
1
1
1
1
rd/s/c
rd/s/c
rd/s/c
rd/s/c
rd/s/c
rd/s/c
rd/s/c
rd/s/c
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
1 = Connect pull-up to D+
dm_pull-up
dp_pull-down
dm_pull-down
id_gnd_out
vbus_drv
1 = Connect pull-up to D-
1 = Connect pull-down to D+
1 = Connect pull-down to D-
1 = Connect ID pin to ground
1 = Power VBUS with charge pump
1 = Discharge VBUS through a resistor
1 = Charge VBUS through a resistor
vbus_dischrg
vbus_chrg
Control Register 3
set - 12h
clr – 13h
1 Æset = 1
1 Æclr = 0
Set & Clear
pwr_dn
1
1
rd/s/c
rd/s/c
bit 0
bit 1
1 = Power Down mode.
1 = turns charge pump OFF.
cp_off
(Charge pump generates 5V for powering VBUS
)
0 = ID comparators ON.
1 = Turns ID comparators OFF.
id_det_off
1
1
1
rd/s/c
rd/s/c
rd/s/c
bit 2
bit 3
bit 4
Note: Powering down ID comparators does not shut
off ID pin pull-up.
Car Kit interrupt select:
0 = Detect < 0.5V level on D+
1 = Detect > 3.0V level on D+
0 = no action.
cr_int_sel
1 = When bdis_acon_en = 0, switches Bit 6 of the
Interrupt Register to indicate Session End
comparator status.
sess_end_en
0 = Internal oscillator drives charge pump
ext_osc
rcs_dis
1
1
rd/s/c
rd/s/c
bit 5
bit 6
1 = External oscillator drives charge pump (Input
source = GPIO_2)
0 = Activate current source. Weak pull-up on ID pin.
1 = Disable (bypass) current source pull-up on ID pin.
Strong pull-up on ID pin.
0 = I2C clock line only transmits.
1 = Bi-directional I2C clock line.
scl_en
1
rd/s/c
bit 7
Bi-directional clock is required if target device is to be
able to control data rate by holding SCL low.
M9999-060805
(408) 955-1690
June 2005
23
MICREL [ MICREL SEMICONDUCTOR ]
