ADP2121-1.8-EVALZ Analog Devices Inc, ADP2121-1.8-EVALZ Datasheet - Page 14

• Manufacturer Part Number: ADP2121-1.8-EVALZ
• Description: 6MHz Volt Mode Buck 500mA Bumped Die
• Manufacturer: Analog Devices Inc

Specifications of ADP2121-1.8-EVALZ

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADP2121
THEORY OF OPERATION
OVERVIEW
The ADP2121 is a high efficiency, synchronous step-down
dc-to-dc converter that provides up to 600 mA of continuous
output current. It operates from a 2.3 V to 5.5 V input voltage
for the 1.8 V, 1.82 V, 1.85 V, and 1.875 V (typical) fixed-output
voltages, and from a 2.9 V to 5.5 V input voltage for the 2.3 V
(typical) output voltage. The 6 MHz operating frequency
enables the use of tiny external components. The internal
control schemes of the ADP2121 give excellent stability and
transient response. External control for mode selection and
device enable provide power-saving options that are aided by
internal features such as synchronous rectification and compen-
sation. Other internal features, such as cycle-by-cycle peak current
limit, soft start, undervoltage lockout, output-to-ground short-
circuit protection, and thermal shutdown, protect the internal
and external circuit components.
V
OUT
FB
C1
AGND
REF
BANDGAP
R1
R2
PFM
BG
COMPENSATION
BG
EAMP
COMPARATOR
B2 EN
PFM
THRESHOLD
AGND
OSCILLATOR
DETECT
6MHz
RAMP
A1 MODE
V(V
SOFT START
SHUTDOWN
IN
THERMAL
)
Figure 51. Internal Block Diagram
THRESHOLD
DETECT
PWM
COMP
Rev. B | Page 14 of 20
THROUGH
CONTROL
PWM/PFM
CONTROL
SHOOT-
LOGIC
AND
2.3V TO 5.5V
V
MODE SELECTION
The ADP2121 has two modes of operation (PWM mode and
auto mode), determined by the state of the MODE pin.
Pull the MODE pin high to force the converter to operate in
PWM mode regardless of the output current. Otherwise, set
MODE low to allow the converter to automatically enter the
power-saving PFM mode at light load currents. Do not leave
this pin floating. The MODE pin is not designed for dynamic
control and should not be changed after the ADP2121 is enabled.
Pulse-Width Modulation (PWM) Mode
The PWM mode forces the part to maintain a fixed frequency
of 6 MHz (typical) over all load conditions. The ADP2121 uses
a hybrid proprietary voltage mode control scheme to control
the duty cycle over load current and line voltage variation. This
control provides excellent stability, transient response, and output
regulation but results in lower efficiencies at light load currents.
BAT
ZXCOMP
PILIM
DETECT
PFM
2.2µF
PDRIVE
NDRIVE
6.3V
X5R
PV
AV
IN
IN
NREF
PREF
VIN
V
FB
A2
IN
PGND
AGND
GND
SW
C2
B1
470nH
4.7µF
X5R
6.3V
V
OUT