ADP1823 Datasheet, PDF (1/32 Pages) Analog Devices – Dual, Interleaved, Step-Down DC-to-DC Controller with Tracking

Dual, Interleaved, Step-Down
DC-to-DC Controller with Tracking
ADP1823
FEATURES
Fixed-frequency operation: 300 kHz, 600 kHz, or
synchronized operation up to 1 MHz
Supply input range: 2.9 V to 20 V
Interleaved operation results in smaller, low cost input
capacitor
All-N-channel MOSFET design for low cost
±0.85% accuracy at 0°C to 70°C
Soft start, thermal overload, current-limit protection
10 μA shutdown supply current
Internal linear regulator
Lossless RDSON current-limit sensing
Reverse current protection during soft start for handling
precharged outputs
Independent Power OK outputs
Voltage tracking for sequencing or DDR termination
Available in 5 mm × 5 mm, 32-lead LFCSP
APPLICATIONS
Telecommunications and networking systems
Medical imaging systems
Base station power
Set-top boxes
Printers
DDR termination
GENERAL DESCRIPTION
The ADP1823 is a versatile, dual, interleaved, synchronous
PWM buck controller that generates two independent output
rails from an input of 2.9 V to 20 V. Each controller can be con-
figured to provide output voltages from 0.6 V to 85% of the
input voltage and is sized to handle large MOSFETs for point-
of-load regulators. The two channels operate 180° out of phase,
reducing stress on the input capacitor and allowing smaller, low
cost components. The ADP1823 is ideal for a wide range of
high power applications, such as DSP and processor core I/O
power, and general-purpose power in telecommunications,
medical imaging, PC, gaming, and industrial applications.
The ADP1823 operates at a pin-selectable, fixed switching
frequency of either 300 kHz or 600 kHz, minimizing external
component size and cost. For noise-sensitive applications, it can
also be synchronized to an external clock to achieve switching
TYPICAL APPLICATION CIRCUIT
IN = 12V
180µF
1µF
PV IN EN1
TRK1 _EN2
TRK2
VREG
180µF
0.47µF
IRLR7807Z
1.2V,
6A
560µF
2.2µH
2kΩ
2kΩ
IRFR3709Z
BST2
BST1
0.47µF
DH1
DH2
ADP1823
SW1
SW2
CSL1 CSL2
DL1
DL2
PGND2
2kΩ
IRFR3709Z
IRLR7807Z
2.2µH
2kΩ
1.8V,
8A
560µF
PGND1 ^FB2
390pF
FB1 COMP2
2kΩ
COMP1
4.53kΩ 3900pF
FREQ
LDOSD
GND SYNC
390pF
1kΩ
3900pF 4.53kΩ
Figure 1. Typical Application Circuit
frequencies between 300 kHz and 1 MHz. The ADP1823
includes soft start protection to prevent inrush current from the
input supply during startup, reverse current protection during
soft start for precharged outputs, as well as a unique adjustable
lossless current-limit scheme utilizing external MOSFET
sensing.
For applications requiring power supply sequencing, the
ADP1823 also provides tracking inputs that allow the output
voltages to track during startup, shutdown, and faults. This
feature can also be used to implement DDR memory bus
termination.
The ADP1823 is specified over the −40°C to +85°C ambient
temperature range, and is available in a 32-lead LFCSP package.
Rev. A
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