Detailed description

STOD13CM

16/25

024087 Rev 1

7.3

Enable pin

The device operates when the EN pin is set high. If the EN pin is set low the device stops

switching, and all internal blocks are turned off. In this condition the current drawn from

are in an off state, so the load is electrically disconnected from the input; this avoids

unwanted current leakage from the input to the load.

7.4

7.5

FBP pin

Two kinds of feedback control loop are implemented in this device to control positive output

voltage VMID. When the FBP pin is connected to AMOLED panel VMID node, external

feedback is used. Thus the control loop regulates positive output voltage VMID based on

FBP. When the pin is connected to AGND, internal feedback is used instead. Thus positive

output voltage VMID is regulated directly. The FBP pin cannot be left floating.

In order to protect the application from FBP track accidental disconnection, it is

recommended to use 1 M

Ω pull-down to AGND on FBP pin.

Proper PCB layout of the FBP track is mandatory; the principle of Kelvin sensing should be

applied as a routing technique. It is suggested to follow Recommended PCB Layout chapter.

7.6

Soft-start and inrush current limiting

device initiates the startup phase. As a first step, the CMID capacitor is charged, and the

P1B switch implements a current limiting technique in order to keep the charge current

voltage level, the P1B switch is fully turned on and the soft-start procedure for the step-up is

Table 7.

(1)

1.

EN

Action

Low

Low

Device off

Low

High

High

Low

Default Negative Output voltage

High

High

Default Negative Output voltage

Table 8.

FBP operation table

FBP

Action

AGND

Internal feedback enabled

VMID at panel

External feedback enabled

Floating

Not allowed