SH3100 Datasheet, PDF (15/80 Pages) Semtech Corporation – Supervisory IC with I2C Interface and PWM

POWER MANAGEMENT
Application Diagrams - Modes 7 to 9
Mode 7 – Normal boost regulation using external
FET & internal feedback divider
VBAK is stepped up from VDD using external
switching FET controlled by PWM.
Regulated output voltage is set by internal DAC8.
Feedback is fixed as VBAK/3.
1 MOhm resistor indicates external switching and
also ensures NMOS is turned off during power up
Register settings
DeviceMode = 001
ComparatorSource = 01 (VBAK)
CLK1HF/LF = 1
ForcedDACValue = xx (to set VDD level)
Set CLK1 frequency as desired
Mode 8 – Buck regulation using external FET &
external feedback divider
Regulated supply is stepped down from VDD using
external switching FET controlled by PWM.
Regulated output voltage is set by internal DAC8
and feedback on SNSE.
1 MOhm resistor indicates external switching and
also ensures PMOS is turned off during power up
Register settings
DeviceMode = 011
ComparatorSource = 11 (SNSE)
CLK1HF/LF = 1
ForcedDACValue = xx (to set VDD level)
Set CLK1 frequency as desired
Mode 9 – Buck regulation using external FET &
internal feedback divider
Regulated supply is stepped down from VDD to
VBAK using external switching controlled by PWM.
Regulated output voltage is set by internal DAC8.
Feedback is fixed as VBAK/3.
1 MOhm resistor indicates external switching and
also ensures PMOS is turned off during power up
Register settings
DeviceMode = 011
ComparatorSource = 01 (VBAK)
CLK1HF/LF = 1
ForcedDACValue = xx (to set VDD level)
Set CLK1 frequency as desired
© 2006 Semtech Corp.
15
SH3100
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