LP87322ESLASHF datasheet(58/75 Pages) TI1

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LP87322B-Q1, LP87322D-Q1, LP87322E-Q1, LP87322F-Q1

SNVSAC5 – SEPTEMBER 2017

www.ti.com

Product Folder Links: LP87322B-Q1 LP87322D-Q1 LP87322E-Q1 LP87322F-Q1

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Table 10. Recommended Buck Output Capacitors (X7R Dielectric)

MANUFACTURER

PART NUMBER

VALUE

CASE SIZE

DIMENSIONS L × W × H

(mm)

VOLTAGE RATING

Murata

GCM31CR71A226KE02

22 µF (10%)

1206

3.2 × 1.6 × 1.6

10 V

9.2.1.4 LDO Input Capacitor Selection

The input capacitors CIN_LDO0 and CIN_LDO1 are shown in the Figure 25. A ceramic input capacitor of 2.2 μF, 6.3 V

is sufficient for most applications. Place the input capacitor as close as possible to the VIN_LDOx pin and AGND

pin of the device. A larger value or higher voltage rating improves the input voltage filtering. Use X7R type of

capacitors, not Y5V or F. DC bias characteristics of capacitors must be considered, minimum effective input

capacitance to ensure good performance is 0.6 μF per LDO input at maximum input voltage including tolerances,

ambient temperature range and aging. See Table 11.

Table 11. Recommended LDO Input Capacitors (X7R Dielectric)

MANUFACTURER

PART NUMBER

VALUE

CASE SIZE

DIMENSIONS L × W × H

(mm)

VOLTAGE RATING

Murata

GCM188R70J225KE22

2.2 µF (10%)

0603

1.6 × 0.8 × 0.8

6.3 V

Murata

GCM21BR71C475KA73

4.7 µF (10%)

0805

2 × 1.25 × 1.25

16 V

9.2.1.5 LDO Output Capacitor Selection

The output capacitors COUT_LDO0 and COUT_LDO1 are shown in the Typical Application. A ceramic output capacitor

of minimum 1.0 μF is required. Place the output capacitor as close to the VOUT_LDOx pin and AGND pin of the

device as possible. Use X7R type of capacitors, not Y5V or F. DC bias characteristics of capacitors must be

considered, minimum effective output capacitance to ensure good performance is 0.4 μF per LDO input at

maximum input voltage including tolerances, ambient temperature range and aging. See Table 12.

The output capacitance must be smaller than the input capacitance in order to ensure the stability of the LDO.

With a 1-μF output capacitor it is recommended to use at least 2.2-μF input capacitor; with a 2.2-μF output

capacitor at least 4.7-μF input capacitance.

The VANA input is used to supply analog and digital circuits in the device. See Table 13 for recommended

components from for VANA input supply filtering.

Table 12. Recommended LDO Output Capacitors (X7R Dielectric)

MANUFACTURER

PART NUMBER

VALUE

CASE SIZE

DIMENSIONS L × W × H (mm)

VOLTAGE RATING

Murata

GCM188R71C105KA64

1 µF (10%)

0603

1.6 × 0.8 × 0.8

16 V

Murata

GCM188R70J225KE22

2.2 µF (10%)

0603

1.6 × 0.8 × 0.8

6.3 V

Table 13. Recommended Supply Filtering Components

MANUFACTURER

PART NUMBER

VALUE

CASE SIZE

DIMENSIONS L × W × H (mm)

VOLTAGE RATING

Murata

GCM155R71C104KA55

100 nF (10%)

0402

1 × 0.5 × 0.5

16 V

Murata

GCM188R71C104KA37

100 nF (10%)

0603

1.6 × 0.8 × 0.8

16 V

9.2.2 Detailed Design Procedure

The performance of the LP87322B/D/E/F-Q1 device depends greatly on the care taken in designing the printed

circuit board (PCB). The use of low-inductance and low serial-resistance ceramic capacitors is strongly

recommended, while proper grounding is crucial. Attention must be given to decoupling the power supplies.

Decoupling capacitors must be connected close to the device and between the power and ground pins to support

high peak currents being drawn from system power rail during turnon of the switching MOSFETs. Keep input and

output traces as short as possible, because trace inductance, resistance, and capacitance can easily become the

performance limiting items. The separate buck regulator power pins VIN_Bx are not connected together

internally. Connect the VIN_Bx power connections together outside the package using power plane construction.

LP87322E/F Datasheet(PDF) 58 Page - Texas Instruments

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