LTH2 Marking, LT3465 datasheet(15/24 Pages) LINER

15 / 24 page

LT3498

3498f

VIN

VOUT2

RFB2

3498 F11

LT3498

SW1

CAP1

SW2

CAP2

FB2

CTRL1

LED1

CTRL2

GND2

GND1

VIN

VOUT2

RFB2

LT3498

SW1

CAP1

SW2

CAP2

FB2

CTRL1

LED1

CTRL2

GND2

GND1

a soft transition occurs between the CTRL2 pin and the

internal reference. Figure 10 shows this behavior.

APPLICATIONS INFORMATION— OLED DRIVER

To set the maximum output voltage, select the values of

RFB2 according to the following equation:

OUT

182

1 215

⎛

⎝⎜

⎞

⎠⎟

•

–,

Ω

When CTRL2 is used to override the internal reference,

the output voltage can be lowered from the maximum

value down to nearly the input voltage level. If the voltage

source driving the CTRL2 pin is located at a distance to

the LT3498, a small 0.1µF capacitor may be needed to

bypass the pin locally.

Choosing a Feedback Node

The single feedback resistor may be connected to the VOUT2

pin or to the CAP2 pin (see Figure 11). Regulating the

VOUT2 pin eliminates the output offset resulting from the

voltage drop across the output disconnect PMOS. Regu-

lating the CAP2 pin does not compensate for the voltage

drop across the output disconnect, resulting in an output

voltage VOUT2 that is slightly lower than the voltage set by

the resistor divider. Under most conditions, it is advised

that the feedback resistor be tied to the VOUT2 pin.

Connecting the Load to the CAP2 Node

The efﬁciency of the converter can be improved by con-

necting the load to the CAP2 pin instead of the VOUT2 pin.

The power loss in the PMOS disconnect circuit is then

made negligible. By connecting the feedback resistor to

the VOUT2 pin, no quiescent current will be consumed

in the feedback resistor string during shutdown since

the PMOS transistor will be open (see Figure 12). The

disadvantage of this method is that the CAP2 node can-

not go to ground during shutdown, but will be limited to

around a diode drop below VIN. Loads connected to the

part should only sink current. Never force external power

supplies onto the CAP2 or VOUT2 pins. The larger value

output capacitor should be placed on the node to which

the load is connected.

Figure 10. CTRL2 to FB2 Transfer Curve

Figure 11. Feedback Connection Using

the CAP2 Pin or the VOUT2 Pin

Figure 12. Improved Efﬁciency

CTRL2 VOLTAGE (V)

0.250

0.500

0.750

1.000

1.500

0.3

0.5

0.8

1.0

3498 F10

1.3

1.5

1.250

VIN

VOUT2

RFB2

ILOAD

3498 F12

LT3498

SW1

CAP1

SW2

CAP2

FB2

CTRL1

LED1

CTRL2

GND2

GND1

LTH2 Marking, LT3465 Datasheet(PDF) 15 Page - Linear Technology

LT3465 Datasheet(HTML) 15 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Datasheet Download

Link URL