REV. D

ADP3041

–11–

COMP is allowed to rise slowly until the control loop limits the

voltage to that required for regulation. SS continues to rise and

no longer affects COMP once soft start is complete.

When

SD goes low, an internal switch discharges the SS

capacitor to return its voltage to zero for soft restart.

Because of the large current that flows into the main MOSFET

switch, it is provided with a separate PGND return to the nega-

tive supply terminal to avoid corrupting the small-signal return,

GND, that can be used as a sense line at the output load point.

Buffers

This family of buffers is designed to drive large capacitive loads

in LCD applications. Each has high output current drive and

rail-to-rail input/output operation and can be powered from a

single 12 V supply. They are also intended for other applications

where low distortion and high output current drive are needed.

Input Overvoltage Protection

As with any semiconductor device, whenever the input exceeds

either supply voltage, attention needs to be paid to the input

overvoltage characteristics. As an overvoltage occurs, the ampli-

fier could be damaged, depending on the voltage level and the

magnitude of the fault current. When the input voltage exceeds

either supply by more than 0.6 V, the internal pin junctions

allow current to flow from the input to the supplies.

This input current is not inherently damaging to the device as

long as it is limited to 5 mA or less. If a condition exists using

the buffers where the input exceeds the supply more than 0.6 V,

a series external resistor should be added. The size of the resis-

tor can be calculated by using the maximum overvoltage divided

by 5 mA. This resistance should be placed in series with the

input exposed to an overvoltage.

Output Phase Reversal

The buffer family is immune to phase reversal. Although the

device’s output does not change phase, large currents due to

input overvoltage could damage the device. In applications

where the possibility of an input voltage exceeding the supply

voltage exists, overvoltage protection should be used as described

in the previous section.

APPLICATION INFORMATION

Output Voltage

12 V. The output voltage is fed back to the ADP3041 via resis-

tor dividers R1 and R2 (Figure 1). The feedback voltage is

1.233 V, so the output voltage is set by the formula

VV

R

R

+









1.233

1

1

2

(1)

Because the feedback bias current is 100 nA maximum, R2 may

have a value up to 100 k

Ω with minimum error due to the bias

current.

Inductor Selection

For most applications, the inductor used with the ADP3041

should be in the range of 1

µH to 22 µH. Several inductor

manufacturers are listed in Table I. When selecting an inductor,

it is important to make sure that the inductor used with the

ADP3041 is able to handle a peak current without saturation, and

that the peak current is below the current limit of the ADP3041.

Table I. Inductor Manufacturers

Part

L (

µH)

Max DCR (m

Ω)Height (mm)

Vendor

CMD4D11-4R7M

4.7

166

1.1

Sumida

CCDRH5D18-100

10

124

2.0

847-545-6700

CR43-4R7

4.7

109

3.5

www.sumida.com

CR43-100

10

182

3.5

DS1608-472

4.7

60

2.9

Coilcraft

DS1608-103

10

75

2.9

847-639-6400

www.coilcraft.com

D52LC-4R7M

4.7

84

2.0

Toko

D52LC-100M

10

137

2.0

847-297-0070

www.tokoam.com