Dual, 2.2MHz, Automotive Synchronous Buck

Converter with 80V Load-Dump Protection

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Pin Description

PIN

NAME

FUNCTION

1, 32

SOURCE2

Converter 2 Internal MOSFET Source Connection. For buck converter operation, connect SOURCE2 to the

switched side of the inductor. For boost operation, connect SOURCE2 to PGND (Figure 5).

2, 3

DRAIN2

Converter 2 Internal MOSFET Drain Connection. For buck converter operation, use the MOSFET as a high-

side switch and connect DRAIN2 to the DC-DC converters supply input rail. For boost converter operation,

use the MOSFET as a low-side switch and connect DRAIN2 to the inductor and diode junction (Figure 5).

4

PGOOD2

Converter Open-Drain Power-Good Output. PGOOD2 goes low when converter 2’s output falls below 92.5%

of its set regulation voltage. Use PGOOD2 and EN1 to sequence the converters.

5

EN2

6

FB2

Converter 2 Feedback Input. Connect FB2 to a resistive divider between converter 2’s output and SGND to

adjust the output voltage. To set the output voltage below 0.8V, connect FB2 to a resistive voltage-divider

from BYPASS to regulator 2’s output (Figure 2). See the Setting the Output Voltage section.

7

COMP2

Converter 2 Internal Transconductance Amplifier Output. See the Compensation section.

8

OSC

connected to the SYNC input. See the Synchronization (SYNC) section.

9

SYNC

External Clock Synchronization Input. Connect SYNC to a 400kHz to 4400kHz clock to synchronize the

switching frequency with the system clock. Each converter frequency is 1/2 of the frequency applied to

SYNC frequency. Connect SYNC to SGND when not used.

10

GATE

Gate Drive Output. Connect to the gate of the external n-channel load-dump protection MOSFET. GATE =

IN_HIGH + 9V (typ) with IN_HIGH = 12V. GATE pulls to IN_HIGH by an internal n-channel MOSFET when V+

raises 2V above IN_HIGH. Leave GATE unconnected if the load-dump protection is not used (MOSFET not

installed).

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ON/OFF

n-Channel Switch Enable Input. Drive ON/OFF high for normal operation. Drive ON/OFF low to turn off the

external n-channel load-dump protection MOSFET and reduce the supply current to 7μA (typ). When

ON/OFF is driven low, both DC-DC converters are disabled and the PGOOD_ outputs are driven low.

Connect to V+ if the external load-dump protection is not used (MOSFET not installed).

12

IN_HIGH

Startup Input. IN_HIGH is protected by internally clamping to 21V (max). Connect a resistor (4k

Ω max) from

IN_HIGH to the drain of the protection switch. Bypass IN_HIGH with a 4.7μF electrolytic or 1μF minimum

ceramic capacitor. Connect to V+ if the external load-dump protection is not used (MOSFET not installed).

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V+

5.5V input operation. Bypass V+ to SGND with a 1μF minimum ceramic capacitor.

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