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ADP1864 Controller Datasheet |
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| Part Number | ADP1864 |
| Description | Constant Frequency Current-Mode Step-Down DC/DC Controller |
| Manufacture | Analog Devices |
| Total Page | 16 Pages |
| Datasheet |
www.DataSheet4U.com
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
APPLICATIONS
Wireless devices
1- to 3-cell Li-Ion battery-powered applications
Set-top boxes
Processor core power supplies
Hard disk drives
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.
470pF
ADP1864
15kΩ
1 COMP
IN 5
2 GND
CS 4
80.6kΩ
3 FB
PGATE 6
174kΩ
0.03Ω
VIN = 3.3V to 10V
10μF
5μH 2.5V, 2.0A
47μF
Figure 1. Typical Applications Diagram
MOSFET = FDC638P
100
VOUT = 2.5V
95
90
85
3.3V
80
75
4.2V
70
65 5.0V
60
0.01
0.1 1.0
EFFICIENCY vs. LOAD CURRENT FOR APPLICATION
10.0
Figure 2. Efficiency vs. Load Current
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2005 Analog Devices, Inc. All rights reserved.
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ADP1864
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description ......................................................................... 1
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ........................................................................ 8
Loop Start-Up ............................................................................... 8
Short-Circuit Protection.............................................................. 9
Undervoltage Lockout (UVLO) ................................................. 9
Overvoltage Lockout Protection (OVP).................................... 9
Soft Start ........................................................................................ 9
REVISION HISTORY
10/05—Revision 0: Initial Version
Application Information................................................................ 10
Duty Cycle ................................................................................... 10
Ripple Current ............................................................................ 10
Sense Resistor.............................................................................. 10
Inductor Value ............................................................................ 10
MOSFET...................................................................................... 11
Diode............................................................................................ 11
Input Capacitor........................................................................... 11
Output Capacitor........................................................................ 11
Feedback Resistors ..................................................................... 12
Layout Considerations................................................................... 13
Example Applications Circuits ..................................................... 14
Outline Dimensions ....................................................................... 15
Ordering Guide .......................................................................... 15
Rev. 0 | Page 2 of 16
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| Features | www.DataSheet4U.com Constant Frequency Current-Mode Step-Down DC/DC Controller in TSOT ADP1864 FEATURES Wide input vo ltage range: 3.15 V to 14 V Wide output voltage range: 0.8 V to input voltage Pin-to-pin compatible with LTC1772, LTC 3801 Up to 94% efficiency 0.8 V ±1.25% reference accuracy over temperature In ternal soft start 100% duty cycle for l ow dropout voltage Current-mode operati on for good line and load transient res ponse 7 μA shutdown current 235 μA qu iescent supply current Short-circuit an d overvoltage protection Small 6-lead T SOT package GENERAL DESCRIPTION The AD P1864 is a compact, inexpensive, consta nt-frequency current-mode step-down DC- to-DC controller. The ADP1864 drives a P-channel MOSFET that regulates an outp ut voltage as low as 0.8 V with ±2% ac curacy, for up to 5 A load currents, fr om input voltages as high as 14 V. The ADP1864 provides system flexibility by allowing accurate setting of the curren t limit with an external resistor, while the output voltage is easi. |
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