ADP2147ACBZ-110-R7 Analog Devices Inc, ADP2147ACBZ-110-R7 Datasheet - Page 11

• Manufacturer Part Number: ADP2147ACBZ-110-R7
• Description: IC REG BUCK 800MA 3MHZ 6WLSCP
• Manufacturer: Analog Devices Inc
• Series: -r
• Type: Step-Down (Buck), PWM - Current Moder

Specifications of ADP2147ACBZ-110-R7

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1.275V, 0.981V
• Current - Output: 800mA
• Frequency - Switching: 3MHz
• Voltage - Input: 2.3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 6-UFBGA, WLCSP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: ADP2147ACBZ-110-R7TR

The ADP2147 is a step-down dc-to-dc regulator that uses a
fixed frequency and high speed current-mode architecture.
The high switching frequency and tiny 6-ball WLCSP package
enable a small step-down dc-to-dc regulator solution.
The ADP2147 operates with an input voltage of 2.3 V to 5.5 V
and regulates an output voltage down to 0.8 V.
CONTROL SCHEME
The ADP2147 operates with a fixed frequency, current-mode
PWM control architecture at medium to high loads for high
efficiency but shifts to a power save mode control scheme at
light loads to lower the regulation power losses. When operating in
PWM mode, the duty cycle of the integrated switches is adjusted
and regulates the output voltage. When operating in power save
mode at light loads, the output voltage is controlled in a hyster-
etic manner, with higher V
the converter is able to stop switching and enters an idle mode,
which improves conversion efficiency.
PWM MODE
In PWM mode, the ADP2147 operates at a fixed frequency of
3 MHz, set by an internal oscillator. At the start of each oscillator
cycle, the pFET switch is turned on, sending a positive voltage
across the inductor. Current in the inductor increases until the
magnitude of the current sense signal crosses the peak inductor
current threshold. This turns off the pFET switch and turns on the
nFET synchronous rectifier, which sends a negative voltage across
the inductor, causing the inductor current to decrease. The
synchronous rectifier stays on for the rest of the cycle.
The ADP2147 regulates the output voltage by adjusting the peak
inductor current threshold.
THEORY OF OPERATION
VOUT
VSEL
OUT
ripple. During part of this time,
ADP2147
UNDERVOLTAGE
OSCILLATOR
LOCKOUT
SOFT START
PSM
COMP
Figure 33. Functional Block Diagram
GM ERROR
AMP
Rev. 0 | Page 11 of 16
CONTROL
PWM/
PSM
EN
CURRENT
ANTISHOOT-
SHUTDOWN
THROUGH
THERMAL
I
DRIVER
POWER SAVE MODE
The ADP2147 smoothly transitions to the power save mode of
operation when the load current decreases below the power
save mode current threshold. When the ADP2147 enters power
save mode, an offset is induced in the PWM regulation level,
which makes the output voltage rise. When the output voltage
reaches a level approximately 1.5% above the PWM regulation
level, PWM operation turns off. At this point, both power
switches are off, and the ADP2147 enters idle mode. C
discharges until V
which point the device drives the inductor to cause V
again to the upper threshold. This process is repeated for as long as
the load current is below the power save mode current
threshold.
Power Save Mode Current Threshold
The power save mode current threshold is set to 100 mA. The
ADP2147 employs a scheme that ensures that this current is
accurately controlled and independent of V
The control scheme also ensures that there is very little hysteresis
between the power save mode current threshold and that of the
PWM mode. The power save mode current threshold is opti-
mized for excellent efficiency across all load currents.
ENABLE/SHUTDOWN
The ADP2147 starts operating with soft start when the EN pin
is toggled from logic low to logic high. Pulling the EN pin low
forces the device into shutdown mode, reducing the supply
current to 0.2 μA (typical).
LIMIT
LOW
AND
COMP
PWM
OUT
falls to the PWM regulation voltage, at
VIN
SW
GND
IN
and V
ADP2147
OUT
OUT
OUT
levels.
to rise