Dual and Combinable Graphics Core

Controller for Notebook Computers

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11

Pin Description (continued)

PIN

NAME

FUNCTION

16

DH2

High-Side Gate-Driver Output for SMPS2. DH2 swings from LX2 to BST2.

17

BST2

Boost Flying-Capacitor Connection for SMPS2. Connect to an external capacitor as shown in Figure 1. An optional

resistor in series with BST2 allows the DH2 turn-on current to be adjusted.

18

LX2

Inductor Connection for SMPS2. Connect LX2 to the switched side of the inductor. LX2 is the lower supply rail for

the DH2 high-side gate driver.

19

DL2

20

PGND

Power Ground

21

greater ceramic capacitor.

22

DL1

23

LX1

Inductor Connection for SMPS1. Connect LX1 to the switched side of the inductor. LX1 is the lower supply rail for

the DH1 high-side gate driver.

24

BST1

Boost Flying-Capacitor Connection for SMPS1. Connect to an external capacitor as shown in Figure 1. An optional

resistor in series with BST1 allows the DH1 turn-on current to be adjusted.

25

DH1

High-Side Gate-Driver Output for SMPS1. DH1 swings from LX1 to BST1.

26

ON1

SMPS1 Enable Input. Drive ON1 high to enable SMPS1. Drive ON1 low to shut down SMPS1.

When both outputs are combined, ON1 is the master control signal to enable/disable the combined output, while

ON2 enables/disables phase 2, allowing 1- or 2-phase operation.

27

CSL1

Negative Current-Sense and Feedback Input for SMPS1. Connect to the negative terminal of the current-sense

element. CSL1 regulates to REFIN1. Figure 10 describes two different current-sensing options.

28

CSH1

Positive Current-Sense Input for SMPS1. Connect to the positive terminal of the current-sense element. Figure 10

describes two different current-sensing options.

29

SKIP1

Low-Noise Mode Control for SMPS1. Connect

SKIP1 to GND for normal Idle Mode (pulse-skipping) operation or to

When both outputs are combined,

SKIP2 is ignored and SKIP1 sets the skip function for both SMPS1 and SMPS2.

30

PGOOD1

SMPS1 Open-Drain Power-Good Output. PGOOD1 is low when SMPS1 is more than 150mV below its regulation

threshold, when a 0V fault occurs, during soft-start, and in shutdown.

PGOOD1 is the voltage-regulation fault indicator when operating in combined mode.

31

DTRANS

Forced-Downward Transient Disable Input. Connect

detection feature when operating in pulse-skipping mode, allowing the output to fall at a rate determined by the

load current and total output capacitance.

Connect

DTRANS to AGND to enable the forced downward-transition detection feature.

32

SLEW1

SMPS1 Slew-Rate Control. Connect a capacitor from SLEW1 to AGND to set the SMPS1 slew rate:

Slew Rate (

During startup and shutdown, SMPS1 ramps at 1/5 the programmed slew rate.

In combined mode, the slew rate is set by both SLEW1 and SLEW2. Connect SLEW1 and SLEW2 together in

combined mode:

Combined Slew Rate (

—

EP

Exposed Backside Pad. Connect the exposed backside pad to AGND.