ISL6446

3

FN7944.0

July 10, 2012

RT

5

This is the operating frequency adjustment pin. By placing a resistor from this pin to SGND, the oscillator frequency can be

programmed from 100kHz to 2.5MHz.

SS1/EN1

SS2/EN2

2, 11

These pins provide enable/disable and soft-start function for their respective controllers. The output is held off when the pin is

pulled to ground. When the chip is enabled, the regulated 30µA pull-up current source charges the capacitor connected from the

pin to ground. The output voltage of the converter follows the ramping voltage on the SS/EN pin. See “Soft-Start and Voltage

Tracking” on page 12 for more details.

LCFB

8

This pin is the feedback pin for the linear controller. An external voltage divider network connected to this pin sets the output

voltage of the linear controller. If the linear controller is not used, tie this pin to VCC.

LCDR

7

Open drain output PNP Transistor or P channel MOSFET Driver. LCDR connects to the base of an external PNP pass transistor or

the gate of the MOSFET to form a positive linear regulator. A small resistor can be inserted between the LCDR and the base of

the PNP pass transistor or the gate of the MOSFET to alleviate thermal stress at output short condition.

OCSET1, 2

converter overcurrent (OC) trip point according to Equation 1:

The voltage on the OCSET pin should not exceed 0.7V above the VIN pin voltage for proper current sensing when the UGATE is

turned on.

SYMBOL

PIN #

DESCRIPTION

I

OC

I

OCSET

R

OCSET

•

r

DS ON

()

---------------------------------------------------

=

(EQ. 1)

Ordering Information

PART NUMBER

(Notes 1, 2, 3)

PART

MARKING

TEMP.

RANGE (°C)

PACKAGE

(Pb-free)

PKG.

DWG. #

ISL6446IAZ

ISL 6446IAZ

-40 to +85

24 Ld QSOP

M24.15

NOTES:

1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications.

2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte

tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil

Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.

3. For Moisture Sensitivity Level (MSL), please see device information page for ISL6446. For more information on MSL please see tech brief TB363.