MC9S12E256 Datasheet, PDF (441/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 14 Dual Output Voltage Regulator (VREG3V3V2)
14.3.2 Register Descriptions
The following paragraphs describe, in address order, all the VREG registers and their individual bits.
14.3.2.1 VREG — Control Register (VREGCTRL)
The VREGCTRL register allows to separately enable features of VREG.
R
W
Reset
Field
2
LVDS
1
LVIE
0
LVIF
7
6
5
4
3
2
1
0
0
0
0
0
0
LVDS
LVIE
LVIF
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 14-2. VREG3V3 — Control Register (VREGCTRL)
Table 14-3. VREGCTRL Field Descriptions
Description
Low-Voltage Detect Status Bit — This read-only status bit reflects the input voltage. Writes have no effect.
0 Input voltage V_DDA is above level V_LVID or RPM or shutdown mode.
1 Input voltage V_DDA is below level V_LVIA and FPM.
Low-Voltage Interrupt Enable Bit
0 Interrupt request is disabled.
1 Interrupt will be requested whenever LVIF is set.
Low-Voltage Interrupt Flag — LVIF is set to 1 when LVDS status bit changes. This flag can only be cleared by
writing a 1. Writing a 0 has no effect. If enabled (LVIE = 1), LVIF causes an interrupt request.
0 No change in LVDS bit.
1 LVDS bit has changed.
NOTE
On entering the reduced-power mode the LVIF is not cleared by the VREG.
14.4 Functional Description
Block VREG is a voltage regulator as depicted in Figure 14-1. The regulator functional elements are the
regulator core (REG), a low-voltage detect module (LVD), a power-on reset module (POR) and a
low-voltage reset module (LVR). There is also the regulator control block (CTRL) which represents the
interface to the digital core logic but also manages the operating modes of VREG.
14.4.1 REG — Regulator Core
VREG, respectively its regulator core has two parallel, independent regulation loops (REG1 and REG2)
that differ only in the amount of current that can be sourced to the connected loads. Therefore, only REG1
providing the supply at V_DD/V_SS is explained. The principle is also valid for REG2.
MC9S12E256 Data Sheet, Rev. 1.08
Freescale Semiconductor
441