High-Power Synchronous HBLED

Drivers with Rapid Current Pulsing

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7

Pin Description

PIN

NAME

FUNCTION

1

PGND

Power-Supply Ground

2, 7

N.C.

No Connection. Not internally connected.

3

DL

Low-Side Gate-Driver Output

4

BST

Boost-Flying Capacitor Connection. Reservoir capacitor connection for the high-side MOSFET driver

supply. Connect a ceramic capacitor between BST and LX.

5

LX

High-Side MOSFET Source Connection

6

DH

High-Side Gate-Driver Output

8, 22, 25

SGND

Signal Ground. SGND is the ground connection for the internal control circuitry. Connect SGND and PGND

together at one point near the IC.

9

CLKOUT

Oscillator Output. If MODE is low, the rising edge of CLKOUT phase shifts from the rising edge of DH by

180°. If MODE is high, the rising edge of CLKOUT phase shifts from the rising edge of DL by 180°.

10

MODE

Buck/Boost Mode Selection Input. Drive MODE low for low-side buck mode operation. Drive MODE high for

boost or high-side buck mode operation. MODE has an internal 5µA pulldown current to ground.

11

EN

Output Enable. Drives EN high or leave unconnected for normal operation. Drive EN low to shut down the

power drivers. EN has an internal 15µA pullup current.

12

RT/SYNC

Switching Frequency Programming. Connect a resistor from RT/SYNC to SGND to set the internal oscillator

frequency. Drive RT/SYNC to synchronize the switching frequency with an external clock.

13

OUTV

Inductor Current-Sense Output. OUTV is an amplifier output voltage proportional to the inductor current.

14

I.C.

Internally Connected. Connect to SGND for proper operation.

15

OVI

Overvoltage Protection. When OVI exceeds the programmed output voltage by 12.7%, the low-side and

the high-side drivers are turned off. When OVI falls 20% below the programmed output voltage, the drivers

are turned on after power-on reset and soft-start cycles are completed.

16

CLP

Current-Error-Amplifier Output. Compensate the current loop by connecting an RC network to ground.

17

EAOUT

Voltage-Error-Amplifier Output. Connect EAOUT to the external gain-setting network.

18

EAN

Voltage-Error-Amplifier Inverting Input

19

DIFF

Differential Remote-Sense Amplifier Output. DIFF is the output of a precision amplifier with SENSE+ and

SENSE- as inputs.

20

CSN

Current-Sense Differential Amplifier Negative Input. The differential voltage between CSN and CSP is

amplified internally by the current-sense amplifier (Gain = 34.5) to measure the inductor current.

21

CSP

Current-Sense Differential Amplifier Positive Input. The differential voltage between CSP and CSN is

amplified internally by the current-sense amplifier (Gain = 34.5) to measure the inductor current.

23

SENSE-

Differential LED Current-Sensing Negative Input. Connect SENSE- to the negative side of the LED current-

sense resistor or to the negative feedback point.

24

SENSE+

Differential LED Current-Sensing Positive Input. Connect SENSE+ to the positive side of the LED current-

sense resistor, or to the positive feedback point.

26

IN

27

ceramic capacitors.

28

Low-Side Driver Supply Voltage

—EP

Exposed Pad. EP is internally connected to SGND. Connect EP to a large-area ground plane for effective

power dissipation. Connect EP to SGND. Do not use as a ground connection.