Constant Frequency Current-Mode
Step-Down DC/DC Controller in TSOT
ADP1864
FEATURES
Wide input voltage range: 3.15 V to 14 V
Wide output voltage range: 0.8 V to input voltage
Pin-to-pin compatible with LTC1772, LTC3801
Up to 94% efficiency
0.8 V ±1.25% reference accuracy over temperature
Internal soft start
100% duty cycle for low dropout voltage
Current-mode operation for good line and load transient
response
7 μA shutdown current
235 μA quiescent supply current
Short-circuit and overvoltage protection
Small 6-lead TSOT package
GENERAL DESCRIPTION
The ADP1864 is a compact, inexpensive, constant-frequency
current-mode step-down DC-to-DC controller. The ADP1864
drives a P-channel MOSFET that regulates an output voltage as
low as 0.8 V with ±2% accuracy, for up to 5 A load currents,
from input voltages as high as 14 V.
The ADP1864 provides system flexibility by allowing accurate
setting of the current limit with an external resistor, while the
output voltage is easily adjustable using two external resistors.
The ADP1864 includes an internal soft start to allow quick
power-up while preventing input inrush current. Additional
safety features include short-circuit protection, output over-
voltage protection, and input under voltage protection.
Current-mode control provides fast and stable load transient
performance, while the 580 kHz operating frequency allows a
small inductor to be used in the system. To further the life of a
battery source, the controller turns on the external P-channel
MOSFET 100% of the duty cycle in dropout.
The ADP1864 operates over the −40°C to +85°C temperature
range and is available in a small, low profile, 6-lead TSOT
package.
APPLICATIONS
Wireless devices
1- to 3-cell Li-Ion battery-powered applications
Set-top boxes
Processor core power supplies
Hard disk drives
MOSFET = FDC638P
100
VOUT = 2.5V
95
ADP1864
15kΩ
1
90
VIN = 3.3V to 10V
IN
5
0.03Ω
10μF
CS
4
5μH
2.5V, 2.0A
47μF
05562-001
COMP
GND
470pF
2
85
3.3V
80
75
4.2V
70
05562-018
80.6kΩ
3
FB
PGATE
6
174kΩ
65
60
0.01
5.0V
0.1
1.0
10.0
EFFICIENCY vs. LOAD CURRENT FOR APPLICATION
Figure 1. Typical Applications Diagram
Figure 2. Efficiency vs. Load Current
Rev. 0
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Specifications subject to change without notice. No license is granted by implication
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Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2005 Analog Devices, Inc. All rights reserved.
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