ADP5040 Analog Devices, ADP5040 Datasheet - Page 25

• Manufacturer Part Number: ADP5040
• Description: Micro PMU with 1.2 A Buck Regulator and Two 300 mA LDOs
• Manufacturer: Analog Devices

Data Sheet
POWER MANAGEMENT UNIT
The
combing one step-down (buck) dc-to-dc regulator and two low
dropout linear regulators (LDOs). The high switching frequency
and tiny 20-pin LFCSP package allow for a small power
management solution.
The regulators are activated by a logic level high applied to the
respective EN pin. The EN1 pin controls the buck regulator, the
EN2 pin controls LDO1, and the EN3 pin controls LDO2. The
MODE pin controls the buck switching operation.
The regulator output voltages are set through external resistor
dividers.
When a regulator is turned on, the output voltage ramp is
controlled through a soft start circuit to avoid a large inrush
current due to the discharged output capacitors.
THEORY OF OPERATION
PGND
AGND
AVIN
VIN1
SW
ADP5040
VDDA
is a micro power management unit (micro PMU)
ADP5040
ANTISHOOT
THROUGH
DRIVER
PWM
COMP
I
LOW
CURRENT
AND
LIMIT
VDDA
CONTROL
BUCK1
PWM/
GM ERROR
PSM
AMP
VIN2
UNDERVOLTAGE
SOFT START
OSCILLATOR
SHUTDOWN
LOCK OUT
THERMAL
SYSTEM
CONTROL
COMP
ENBK
PSM
LDO1
Figure 101. Functional Block Diagram
85Ω
Rev. 0 | Page 25 of 40
VOUT1 FB1
FB2
VOUT2
The buck regulator can operate in forced PWM mode if the
MODE pin is at a logic high level. In forced PWM mode, the
switching frequency of the buck is always constant and does not
change with the load current. If the MODE pin is at a logic low
level, the switching regulator operates in auto PWM/PSM mode.
In this mode, the regulator operates at fixed PWM frequency
when the load current is above the power saving current threshold.
When the load current falls below the power save current
threshold, the regulator enters power saving mode, where the
switching occurs in bursts. The burst repetition rate is a
function of the current load and the output capacitor value.
This operating mode reduces the switching and quiescent
current losses.
600Ω
ENLDO1
ENLDO2
ENBK
ENLDO1
MODE
OPMODE_FUSES
VIN3
CONTROL
& MODE
ENABLE
VDDA
SEL
CONTROL
LDO2
ENLDO2
600Ω
FB3
ADP5040
VOUT3
MODE
EN1
EN2
EN3