LTC2926IGN datasheet(25/28 Pages) LINER

25 / 28 page

LTC2926

2926fa

APPLICATIO S I FOR ATIO

Under worst-case conditions, FB pin voltages may reach

the maximum clamp voltage of 2.4V. To limit the slave

voltage offset to below 100mV, choose RFB ≥ 23 • RL.

Add a resistor in parallel with the load to strengthen weak

resistive loads as required.

Start-Up Delays

Often power supplies do not start up immediately when

their input supplies are applied. If the LTC2926 tries to ramp

up these power supplies as soon as the input supply is

present, the start-up of the outputs may be delayed, which

defeats the tracking circuit. Make sure the ON pin does not

initiate ramp-up until all supply sources are available.

RAMP Pin Clamp

The RAMP pin is weakly clamped to the VCC pin. When

MGATE and RAMP are tied together their pin voltages will

not exceed VCC + 1V. If the RAMP pin is driven by a low

impedance source that can exceed VCC, include a series

resistor to limit the current to <20µA. Use 50k

Ωpersource

volt above VCC.

Figure 24. Tracking Effects of Weak Resistive Load

Figure 25. Layout Considerations

2926 F24

500mV/DIV

MASTER

SLAVE2

SLAVE1

5ms/DIV

LARGE

τL = RLCL

RL ≈ RFB

SLAVE

LOAD

2926 F25

OUT

SENSE

100

Ω

KELVIN-SENSE

CONNECTIONS

KELVIN-SENSE

CONNECTIONS

KELVIN-SENSE

CONNECTIONS

SUPPLY

MODULE

MINIMIZE

TRACE LENGTH

MINIMIZE

TRACE

LENGTH

LTC2926

GND

SGATE1

GND

FB1

VCC

RFB

RFA

0.1

µF

Ω

Layout Considerations

Be sure to place a 0.1µF bypass capacitor as near as pos-

sible to the supply pin of the LTC2926.

To minimize the noise on the slave supplies’ outputs, keep

the traces connecting the FB pins of the LTC2926 and the

feedback nodes of the slave supplies’ resistive voltage

dividers as short as possible. In addition, do not route

those traces next to signals with fast transitions times.

To get the best compensation of the series I • R drops

of the external MOSFETs, make sure the supply output

nodes and the supply generator sense connections use

Kelvin-sensing. The feedback resistive voltage divider

should Kelvin-sense the slave supply output node for

accuracy, as well.

LTC2926IGN 数据表(PDF) 25 Page - Linear Technology

LTC2926IGN 数据表(HTML) 25 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 25 26 27 28

数据表下载

链接网址

LTC2926IGN 数据表(PDF) 25 Page - Linear Technology

LTC2926IGN 数据表(HTML) 25 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 25 26 27 28

数据表 下载

链接网址

数据表下载