ADP1607

Data Sheet

Rev. C | Page 10 of 16

THEORY OF OPERATION

SW

+

+

VIN

N

RESET

AGND

GND

1

L1

A

5

2

4

EN

S

R

QP

QN

RP

SW

P

6

OFF

ON

3

FB

R1

R2

PFM

COMPARATOR

PWM

COMPARATOR

CURRENT-LIMIT

COMPARATOR

TSD

COMPARATOR

PFM

CONTROL

SHUTDOWN

ZERO

CROSS

PMOS

BULK

CONTROL

P DRIVER

CURRENT

SENSING

N DRIVER

OSCILLATOR

SOFT

START

ERROR

AMPLIFIER

BULK

CONTROL

Figure 24. Block Diagram

OVERVIEW

The ADP1607 is a high efficiency, synchronous, fixed

frequency, step-up dc-to-dc switching converter with an

adjustable output voltage between 1.8 V and 3.3 V for use

in portable applications.

The 2 MHz operating frequency enables the use of small

footprint, low profile external components. Additionally, the

synchronous rectification, internal compensation, internal fixed

current limit, and current-mode architecture allow for excellent

transient response and a minimal external part count. Other

key features include fixed PWM and light load PFM mode

options, true output isolation, thermal shutdown (TSD), and

logic controlled enable.

ENABLE/SHUTDOWN

The EN input turns the ADP1607 on or off. Connect EN to

GND or logic low to shut down the part and reduce the current

consumption to 0.06 µA (typical). Connect EN to VIN or logic

floating.

MODES OF OPERATION

The ADP1607 is available in a fixed PWM mode only option

for noise sensitive applications or in an auto PFM-to-PWM

transitioning mode option to optimize power at light loads.

Pulse-Width Modulation (PWM) Mode

The PWM version of the ADP1607 utilizes a current-mode

PWM control scheme to force the part to maintain a fixed

2 MHz fixed frequency while regulating the output voltage over

all load conditions. The auto mode version of the ADP1607

operates in PWM for higher load currents. In PWM, the output

voltage is monitored at the FB pin through the external resistive

voltage divider. The voltage at FB is compared to the internal

1.259 V reference by the internal error amplifier. This current-

mode PWM regulation system allows fast transient response

and tight output voltage regulation. PWM mode operation

results in lower efficiencies than PFM mode at light loads.

Auto Mode

Auto mode is a power-saving feature that forces the auto version

of the ADP1607 to switch between PFM and PWM in response

to output load changes. The auto version of the ADP1607