900844 Datasheet, PDF (64/118 Pages) Freescale Semiconductor, Inc – Integrated Power Management IC for Ultra-mobile and Embedded Applications

FUNCTIONAL DEVICE OPERATION
POWER SUPPLIES
The output current is measured internally, digitized by the ADC, and stored in a register for the processor to access.
The peak current is sensed internally for over-current protection purposes. If an over-current condition is detected, the
regulator will limit the current through cycle by cycle operation and alert the system through the V21FAULT signal, which will in
turn assert the VRFAULT Interrupt signal.
VPWR
CIN 21
PVIN 21
V21
CO21
SW21
L21
PGND21
FB21
ISENSE 5
Driver
Controller
Internal
Compensation _Z2
Z1
EA
V R EF
CTLV21
AOACCTLV21
V21FAULT
SPI
Interface
Figure 30. V21 Detailed Internal Block Diagram
Main Features
• Uses the V_PWR rail as its power supply
• It is used as a pre-regulator to many LDO rails, for enhanced efficiency and reduced thermal dissipation.
• Uses Integrated MOSFETs
• 4.0 MHz switching frequency
• High efficiency operating modes depending on load conditions
• Output can be discharged through the low side switch.
• Peak current sensing with over-current protection
• Uses internal compensation
• Gate drive circuits are supplied directly from VPWR
Efficiency Curves
Figure 31 efficiency curves are calculated under PWM mode, based on the recommended external component values and
typical output voltage of 2.1 V. 3.0 V ≤ V_PW ≤ 4.4 V.
900844
64
Analog Integrated Circuit Device Data
Freescale Semiconductor