Constant Frequency Current-Mode

Step-Down DC/DC Controller in TSOT

ADP1864

Rev. 0

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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.

ADP1864

COMP

GND

FB

PGATE

IN

CS

47

μF

174k

Ω

80.6k

Ω

15k

Ω

470pF

0.03

Ω

10

μF

2.5V, 2.0A

VIN = 3.3V to 10V

5

μH

1

2

3

4

5

6

100

60

0.01

10.0

EFFICIENCY vs. LOAD CURRENT FOR APPLICATION

0.1

1.0

95

90

85

80

75

70

65

3.3V

4.2V

5.0V

VOUT = 2.5V

MOSFET = FDC638P

Figure 1. Typical Applications Diagram

Figure 2. Efficiency vs. Load Current