ACT6330

Rev0, 02-Apr-08

STEP-UP DC/DC CONVERTER (REG2)

Innovative Power

TM

- 11 -

www.active-semi.com

Copyright © 2008 Active-Semi, Inc.

ActivePMU

FUNCTIONAL DESCRIPTION

General Description

REG2 is a highly efficient step-up DC/DC converter

that employs a fixed frequency, current-mode,

PWM architecture. This regulator is optimized for

use in a wide range of applications including gen-

eration constant voltage of up to 20V.

Over-Voltage Protection

REG2 features internal over-voltage protection

(OVP) circuitry which protects the system from fault

conditions. The ACT6330’s OVP threshold is set at

22V, and if necessary, regulates the output voltage

to ensure that it never exceeds this voltage.

ACT6330 requires a 10kΩ resistor connected from

output capacitor to OVP2 pin.

Thermal Protection

The Thermal shutdown protection prevents exces-

sive thermal stress, please refer to Thermal Shut-

down Protection

for more information.

Enabling and Disabling REG2

REG2 is enabled or disabled using ON2. Drive ON2

to a logic-high to enable REG2. Drive ON2 to a

logic-low to disable REG2, reducing supply current

to less than 1µA. As with all non-synchronous step-

up DC/DC converter, REG2’s application circuit pro-

cedures a DC current path between the input and

the output in shutdown mode. It is important to con-

sider the effect that this may have in your applica-

tion.

Soft-start

REG2 includes soft-start circuitry. When enabled,

the output voltage of REG2 tracks an internal 80µs

soft-start ramp.

As seen in Figure 1 and Figure 2, the output tracks

the internal soft-start ramp and powers up in a

monotonic maner that is independent of loading.

This circuitry ensures that the output powers up in a

controlled maner, greatly simplifying power turn-on

design considerations.

Compensation and Stability

REG2 utilizes current-mode control and an internal

compensation network to optimize transient per-

formance, ease compensation, and improve stabil-

ity over a wide range of operating conditions. REG2

is a flexible regulator, and with just a simple compo-

nent, choice can be optimized to achieve minimum

total solution size in applications that require the

smallest possible footprint, or can be optimized to

achieve the highest possible efficiency.

Figure 1:

REG2 Startup Waveform into no load

Figure 2:

REG2 Startup Waveform into full load

Output Voltage Selection

Figure 3 shows the feedback network necessary to

set the output voltage when using the adjustable

voltage option. Select components as follows: Set

equation:

Figure 3:

Output Voltage Setting

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+

=

2

FB

1

FB

2

FB

2

OUT

R

R

1

V

V

(1)

CH2

CH1

TIME: 250µs/div

CH2

CH1

TIME: 250µs/div

ACT6330

FB2