ISD91200 Series Technical Reference Manual
Release Date: Sep 16, 2019
- 409 -
Revision 2.4
7.4.4
VMID Reference Voltage Generation
The analog path and blocks require a low
noise, mid-rail, Voltage reference for operation,
the VMID generation block provides this.
Control of this block allows user to power down
the block, select its power down condition and
control over the reference impedance. The
block consists of a switchable resistive divider
connected to the device VMID pin. A 4.7µF
capacitor should be placed on this pin and
returned to analog ground (VSSA) as shown
in .
Before using the SDADC, PGA or other analog
blocks, the VMID reference needs to be
enabled. A low impedance option allows fast
charging of the external noise de-coupling
capacitor, while a higher impedance options
provides lower power consumption. A pulldown
option allows the reference to be discharged
when off.
VMID
R
R
VSSA
LDO15
4.7uF
Internal
Reference
Note: LDO15 is IC internal signal
Figure 7-6 VMID Reference Generation