SH3100IMTR SEMTECH [Semtech Corporation], SH3100IMTR Datasheet - Page 70

• Manufacturer Part Number: SH3100IMTR
• Description: Supervisory IC with I2C Interface and PWM
• Manufacturer: SEMTECH [Semtech Corporation]

Low Dropout Linear Regulator (LDO)
The LDO function provides low-dropout linear regulation
from VDD to the PWM pin. All other PWM pin related func-
tions are disabled in this mode.
The LDO is intended as a low-power support feature for
simple low-cost applications. It has good VDD high fre-
quency noise rejection so can be used to clean up a VDD
supply.
The output voltage on PWM is determined by the DACLev-
el setting as per the previous table. The voltage on PWM
is divided by three and regulated to the same voltage as
the DAC8.
These LDO specifi cations assume a 1μF ceramic load ca-
pacitor on PWM:
© 2006 Semtech Corp.
POWER MANAGEMENT
Functional Descriptions
Note: Only DAC levels of 1V and above are valid in this mode.
Parameter
VDD input voltage
PWM output voltage
No load standby current
Line regulation
Load regulation
VDD noise rejection (100 kHz square wave
on VDD, >250 mV headroom)
Max load current (VLDO = 3 V)
Max load current (VLDO = 4.5 V)
Dropout at 10 mA load (50 mV headroom)
PWM Drift (DAC8 disconnected)
10 Hz to 100 kHz RMS output noise
(continued)
Symbol
VDD
VLDO
Idd
REGlin
REGload
PSRR
Iload1
Iload2
Vdo
Vdrift
Ntot
70
There is also a feature to allow the DAC8 to be used for
an ADC conversion while the LDO is active. To do this, the
MaintainRegulatorOp bit in the Confi g register should be
set prior to initiating a conversion. This disconnects the
LDO regulator input from the DAC8 and holds the refer-
ence level on a capacitor while the DAC8 is used for the
conversion. When the conversion is complete, the DAC8 is
reset to the correct level and reconnected to the LDO. Due
to internal leakage, it is recommended that the maximum
disconnect period is kept to 1ms or less.
Min
3.1
3
30
10
15
Max
5.5
4.5
250
10
2
200
300
100
Units
V
V
μA
mV/V
mV/mA
dB
mA
mA
mV
mV/ms
μV
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SH3100