CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
521
Switch Mode Pump (SMP)
31.3
Register Definitions
The following register is associated with the Switch Mode Pump (SMP). The register description below has an associated reg-
ister table showing the bit structure of the register. The bit in the table that is grayed out is a reserved bit and is not detailed in
the register description. Reserved bits should always be written with a value of ‘0’.
31.3.1
VLT_CR Register
The Voltage Monitor Control Register (VLT_CR) is used to
set the trip points for POR, LVD, and the supply pump.
The VLT_CR register is cleared by all resets, which can
cause reset cycling during very slow supply ramps to 5 V
when the POR range is set for the 5-V range. This is
because the reset clears the POR range setting back to 3 V
and a new boot/start-up occurs (possibly many times). The
user can manage this with Sleep mode and/or reading volt-
age status bits, if such cycling is an issue.
Bit 7: SMP.
This bit controls whether or not the SMP will
turn on when the supply (Vdd) voltage has dropped below
the trip point set by VM[2:0]. The SMP is enabled when the
SMP bit is ‘0’. Thus, the SMP is on by default. If this bit is set
to ‘1’ the SMP will not turn on regardless of the supply volt-
age level.
Bits 5 and 4: PORLEV[1:0].
These bits set the Vdd level at
which PPOR switches to one of three valid values. Note that
11b is a reserved value and therefore should not be used.
The three valid settings for these bits are:
■
00b (2.9 V operation)
■
01b (4.4 V operation)
■
10b (4.65 V operation)
See the “DC POR and LVD Specifications” table in the Elec-
trical Specifications section of the PSoC device data sheet
for voltage tolerances for each setting.
Bit 3: LVDTBEN.
This bit is ANDed with LVD to produce a
throttle-back signal that reduces CPU clock speed, when
low voltage conditions are detected. When the Throttle-Back
signal is asserted, the CPU speed bits in the OSC_CR0 reg-
ister are reset, forcing the CPU speed to 3 MHz or EXTCLK
/ 8.
Bits 2 to 0: VM[2:0].
These bits set the Vdd level at which
LVD and the Pump Comparator switches.
See the “DC POR and LVD Specifications” table in the Elec-
trical Specifications section of the PSoC device data sheet
for voltage tolerances for each setting.
For additional information, refer to the
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Access
1,E3h
SMP
PORLEV[1:0]
LVDTBEN
VM[2:0]
RW : 00
Summary of Contents for CY8C28 series
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