Renesas Electronics Switching Regulators & Controllers 2,400+

Reset All
Part RoHS Manufacturer Other IC type Temperature Grade No. of Terminals Package Code Package Shape Surface Mount Total Dose (V) Maximum Switching Frequency Package Body Material Approvals (V) Maximum Supply Current (Isup) Maximum Output Current Trim or Adjustable Output (V) No. of Functions No. of Channels Technology Screening Level Nominal Bandwidth Terminal Form Main Out Ripple Voltage Control Technique Nominal Negative Supply Voltage (Vsup) Main Output Efficiency Nominal Supply Voltage (Vsup) Maximum Voltage Tolerance Power Supplies (V) Switcher Config Package Style (Meter) Package Equivalence Code Sub-Category Terminal Pitch Maximum Operating Temperature Minimum Output Voltage Control Mode Protection(s) Maximum Line Regulation Maximum Total Power Output Minimum Operating Temperature Terminal Finish Maximum Output Voltage Terminal Position JESD-30 Code Moisture Sensitivity Level (MSL) Maximum Supply Voltage (Vsup) Maximum Seated Height Height Width (mm) Qualification Maximum Load Regulation Minimum Supply Voltage (Vsup) Nominal Input Voltage Warm-Up Time Additional Features Minimum Input Voltage Maximum Negative Input Voltage JESD-609 Code Maximum Time At Peak Reflow Temperature (s) No. of Outputs Peak Reflow Temperature (C) Nominal Threshold Voltage (V) Length Adjustable Threshold Nominal Output Voltage Maximum Input Voltage

ZL2004ALNNT-01

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

32

HVQCCN

SQUARE

YES

400 kHz

PLASTIC/EPOXY

1

NO LEAD

PULSE WIDTH MODULATION

BUCK

CHIP CARRIER, HEAT SINK/SLUG, VERY THIN PROFILE

.5 mm

65 Cel

0 Cel

MATTE TIN

QUAD

S-PQCC-N32

.9 mm

5 mm

8.6 V

0.9V TO 1.1V OUTPUT RANGE

8 V

e3

5 mm

10 V

UPC1905CX-A

Renesas Electronics

SWITCHING CONTROLLER

OTHER

16

DIP

RECTANGULAR

NO

500 kHz

PLASTIC/EPOXY

1.2 A

1

BIPOLAR

THROUGH-HOLE

PULSE WIDTH MODULATION

SINGLE

IN-LINE

DIP16,.3

Switching Regulator or Controllers

2.54 mm

85 Cel

VOLTAGE-MODE

-20 Cel

TIN BISMUTH

DUAL

R-PDIP-T16

5.08 mm

7.62 mm

Not Qualified

18 V

12 V

e6

10

260

30 V

IPM6210ACA

Renesas Electronics

DUAL SWITCHING CONTROLLER

OTHER

28

SSOP

RECTANGULAR

YES

300 kHz

PLASTIC/EPOXY

.4 A

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE, SHRINK PITCH

.635 mm

85 Cel

CURRENT-MODE

-10 Cel

DUAL

R-PDSO-G28

1.75 mm

3.895 mm

5 V

OUTPUT VOLTAGE RANGE FROM 0.925 TO 2 V AND NOMINAL 1.5 V

4.75 V

9.905 mm

5.25 V

HIP6311ACBZA-T

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

20

SOP

RECTANGULAR

YES

1500 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE

1.27 mm

70 Cel

0 Cel

MATTE TIN

DUAL

R-PDSO-G20

2.65 mm

7.5 mm

5 V

4.75 V

e3

12.8 mm

5.25 V

RAA2116054GP3#HA0

Renesas Electronics

SWITCHING REGULATOR

HIP6005BCB-T

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

20

SOP

RECTANGULAR

YES

200 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE

70 Cel

VOLTAGE-MODE

0 Cel

DUAL

R-PDSO-G20

12 V

10.8 V

13.2 V

RAA489800A2GNP#AA0

Renesas Electronics

MATTE TIN

3

e3

30

260

EL7536IYZ-T7

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

10

TSSOP

SQUARE

YES

1750 kHz

PLASTIC/EPOXY

1.5 A

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

.5 mm

85 Cel

VOLTAGE-MODE

-40 Cel

MATTE TIN

DUAL

S-PDSO-G10

2

1.1 mm

3 mm

3.3 V

2.5 V

e3

30

260

3 mm

5.5 V

5962R0251101TXC

Renesas Electronics

SWITCHING CONTROLLER

AUTOMOTIVE

20

DFP

RECTANGULAR

YES

CERAMIC, METAL-SEALED COFIRED

1

MIL-PRF-38535

FLAT

PULSE WIDTH MODULATION

FLATPACK

125 Cel

-50 Cel

DUAL

R-CDFP-F20

Qualified

12 V

20 V

EL7556DCM

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

28

SOP

RECTANGULAR

YES

UNSPECIFIED

9 A

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE

85 Cel

CURRENT-MODE

-40 Cel

DUAL

R-XDSO-G28

5 V

VOUT=(1-3.8 VOLT)

5962F0251101V9A

Renesas Electronics

SWITCHING REGULATOR

AUTOMOTIVE

16

DIE

RECTANGULAR

YES

300k Rad(Si)

1000 kHz

CERAMIC, METAL-SEALED COFIRED

1

BICMOS

MIL-PRF-38535 Class V

NO LEAD

PULSE WIDTH MODULATION

SINGLE

UNCASED CHIP

125 Cel

-50 Cel

UPPER

R-CUUC-N16

Qualified

12 V

12 V

NOT SPECIFIED

NOT SPECIFIED

20 V

EL7564CRE-T7

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

28

HTSSOP

RECTANGULAR

YES

1000 kHz

PLASTIC/EPOXY

5 A

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE, HEAT SINK/SLUG, THIN PROFILE, SHRINK PITCH

.65 mm

85 Cel

CURRENT-MODE

-40 Cel

DUAL

R-PDSO-G28

1.2 mm

4.4 mm

5 V

VOUT=(1 -3.8 VOLT)

4.5 V

NOT SPECIFIED

NOT SPECIFIED

9.7 mm

5.5 V

ICL7660CBA-T

Renesas Electronics

SWITCHED CAPACITOR CONVERTER

COMMERCIAL

8

SOP

RECTANGULAR

YES

10 kHz

PLASTIC/EPOXY

.5 mA

1

CMOS

GULL WING

DOUBLER

SMALL OUTLINE

SOP8,.24

1.27 mm

70 Cel

-1.5 V

0 Cel

-10 V

DUAL

R-PDSO-G8

1

1.75 mm

3.9 mm

5 V

1.5 V

4.9 mm

10 V

5962F9955801QEX

Renesas Electronics

DUAL SWITCHING CONTROLLER

AUTOMOTIVE

16

DIP

RECTANGULAR

NO

300k Rad(Si)

500 kHz

CERAMIC, METAL-SEALED COFIRED

1 A

1

BICMOS

MIL-PRF-38535 Class Q

THROUGH-HOLE

PULSE WIDTH MODULATION

BOOST

IN-LINE

2.54 mm

125 Cel

VOLTAGE-MODE

-50 Cel

DUAL

R-CDIP-T16

5.08 mm

7.62 mm

Qualified

ALSO OPERATES IN CURRENT MODE

12 V

30 V

5962F0251101VXX

Renesas Electronics

SWITCHING CONTROLLER

AUTOMOTIVE

20

DFP

RECTANGULAR

YES

1000 kHz

CERAMIC, METAL-SEALED COFIRED

1 A

1

BICMOS

MIL-PRF-38535

FLAT

PULSE WIDTH MODULATION

PUSH-PULL

FLATPACK

1.27 mm

125 Cel

VOLTAGE-MODE

-50 Cel

DUAL

R-CDFP-F20

2.92 mm

6.92 mm

Qualified

ALSO CAN BE CONFIGURED IN CURRENT MODE

HIP6301VCBZA-T

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

20

SOP

RECTANGULAR

YES

1500 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

PHASE-SHIFT

SMALL OUTLINE

SOP20,.4

Switching Regulator or Controllers

1.27 mm

70 Cel

CURRENT/VOLTAGE-MODE

0 Cel

MATTE TIN

DUAL

R-PDSO-G20

3

2.65 mm

7.5 mm

Not Qualified

5 V

4.75 V

e3

12.8 mm

5.25 V

5962L0724912V9A

Renesas Electronics

SWITCHING CONTROLLER

23

DIE

SQUARE

YES

50k Rad(Si)

1000 kHz

UNSPECIFIED

5.5 mA

1 A

1

BICMOS

MIL-PRF-38535 Class V

NO LEAD

PULSE WIDTH MODULATION

BUCK-BOOST

UNCASED CHIP

DIE OR CHIP

125 Cel

CURRENT-MODE

-55 Cel

Gold (Au)

UPPER

S-XUUC-N23

Qualified

9 V

e4

13.2 V

P62000NLG8

Renesas Electronics

DUAL SWITCHING CONTROLLER

OTHER

64

HVQCCN

SQUARE

YES

1000 kHz

UNSPECIFIED

25 mA

1

NO LEAD

PULSE WIDTH MODULATION

5 V

BUCK

CHIP CARRIER, HEAT SINK/SLUG, VERY THIN PROFILE

LCC64,.35SQ,20

Switching Regulator or Controllers

.5 mm

85 Cel

CURRENT-MODE

0 Cel

MATTE TIN

QUAD

S-XQCC-N64

3

1 mm

9 mm

Not Qualified

5 V

4.75 V

e3

30

260

9 mm

5.25 V

ZL8800ALAFTK

Renesas Electronics

SWITCHING CONTROLLER

INDUSTRIAL

44

HVQCCN

SQUARE

YES

1334 kHz

PLASTIC/EPOXY

1

NO LEAD

PULSE WIDTH MODULATION

BUCK

CHIP CARRIER, HEAT SINK/SLUG, VERY THIN PROFILE

.5 mm

85 Cel

-40 Cel

MATTE TIN

QUAD

S-PQCC-N44

2

1 mm

7 mm

12 V

4.5 V

e3

7 mm

14 V

ZMD31030AAD

Renesas Electronics

EL7584IR-T7

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

24

TSSOP

RECTANGULAR

YES

1100 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

BOOST

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

.65 mm

85 Cel

-40 Cel

DUAL

R-PDSO-G24

1.2 mm

4.4 mm

3.3 V

2 V

7.8 mm

14 V

UPD168807K9-4EG-E1-A

Renesas Electronics

SWITCHING CONTROLLER

OTHER

48

HVQCCN

SQUARE

YES

1500 kHz

PLASTIC/EPOXY

1.9 A

1

NO LEAD

PULSE WIDTH MODULATION

PUSH-PULL

CHIP CARRIER, HEAT SINK/SLUG, VERY THIN PROFILE

LCC48,.24SQ,16

Switching Regulator or Controllers

.4 mm

85 Cel

CURRENT-MODE

-20 Cel

QUAD

S-PQCC-N48

.9 mm

6 mm

Not Qualified

7.4 V

4 V

6 mm

3.3 V

14.5 V

ICL7660SIBA-T13

Renesas Electronics

SWITCHED CAPACITOR CONVERTER

INDUSTRIAL

8

SOP

RECTANGULAR

YES

10 kHz

PLASTIC/EPOXY

1

CMOS

GULL WING

DOUBLER

SMALL OUTLINE

SOP8,.25

1.27 mm

85 Cel

-40 Cel

DUAL

R-PDSO-G8

1.75 mm

3.9 mm

5 V

1.5 V

4.9 mm

12 V

ZL6105ALAFTKR5553

Renesas Electronics

SWITCHING CONTROLLER

ZL6105ALAFTKR5554

Renesas Electronics

SWITCHING CONTROLLER

5962F9955801QEC

Renesas Electronics

DUAL SWITCHING CONTROLLER

AUTOMOTIVE

16

DIP

RECTANGULAR

NO

300k Rad(Si)

500 kHz

CERAMIC, METAL-SEALED COFIRED

1 A

1

BICMOS

MIL-PRF-38535 Class Q

THROUGH-HOLE

PULSE WIDTH MODULATION

BOOST

IN-LINE

2.54 mm

125 Cel

VOLTAGE-MODE

-50 Cel

Gold (Au)

DUAL

R-CDIP-T16

5.08 mm

7.62 mm

Qualified

ALSO OPERATES IN CURRENT MODE

12 V

e4

NOT SPECIFIED

NOT SPECIFIED

21.34 mm

30 V

HIP6021CBZ-T

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

28

SOP

RECTANGULAR

YES

200 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE

70 Cel

VOLTAGE-MODE

0 Cel

MATTE TIN

DUAL

R-PDSO-G28

12 V

10.8 V

e3

13.2 V

UPC1100C-A

Renesas Electronics

DUAL SWITCHING CONTROLLER

OTHER

16

DIP

RECTANGULAR

NO

500 kHz

PLASTIC/EPOXY

.025 A

1

BIPOLAR

THROUGH-HOLE

PULSE WIDTH MODULATION

SINGLE

IN-LINE

DIP16,.3

Switching Regulator or Controllers

2.54 mm

85 Cel

VOLTAGE-MODE

-20 Cel

TIN BISMUTH

DUAL

R-PDIP-T16

5.08 mm

7.62 mm

Not Qualified

6 V

3.6 V

e6

10

260

40 V

ZSPM4012AA1W15

Renesas Electronics

HA16342NT

Renesas Electronics

SWITCHING CONTROLLER

INDUSTRIAL

26

SDIP

RECTANGULAR

NO

400 kHz

PLASTIC/EPOXY

2 A

1

THROUGH-HOLE

PULSE WIDTH MODULATION

SINGLE

IN-LINE, SHRINK PITCH

HSDIP24,.4

Switching Regulator or Controllers

1.778 mm

105 Cel

CURRENT-MODE

-40 Cel

DUAL

R-PDIP-T26

5.08 mm

10.16 mm

Not Qualified

12 V

9.5 V

27.6 mm

18 V

HIP6004BCV-T

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

20

TSSOP

RECTANGULAR

YES

200 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

.65 mm

70 Cel

VOLTAGE-MODE

0 Cel

DUAL

R-PDSO-G20

1.2 mm

4.4 mm

12 V

10.8 V

NOT SPECIFIED

NOT SPECIFIED

6.5 mm

13.2 V

EL7530IYZ-T13

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

10

TSSOP

SQUARE

YES

1600 kHz

PLASTIC/EPOXY

.5 mA

.8 A

1

GULL WING

PULSE WIDTH MODULATION

3.3 V

BUCK

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

TSSOP10,.2,20

.5 mm

85 Cel

VOLTAGE-MODE

-40 Cel

MATTE TIN

DUAL

S-PDSO-G10

3

1.1 mm

3 mm

3.3 V

PFM TECHNIQUE ALSO USED

2.5 V

e3

30

260

3 mm

1.8 V

5.5 V

M62213FP

Renesas Electronics

SWITCHING CONTROLLER

OTHER

10

SOP

RECTANGULAR

YES

700 kHz

PLASTIC/EPOXY

1 A

1

BIPOLAR

GULL WING

PULSE WIDTH MODULATION

PUSH-PULL

SMALL OUTLINE

SOP10,.3

Switching Regulator or Controllers

1.27 mm

85 Cel

CURRENT-MODE

-20 Cel

DUAL

R-PDSO-G10

2.1 mm

5.7 mm

Not Qualified

14 V

9 V

6.8 mm

35 V

EL7512CY-T7

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

10

TSSOP

SQUARE

YES

1200 kHz

PLASTIC/EPOXY

1.5 A

1

GULL WING

PULSE WIDTH MODULATION

5 V

BOOST

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

TSSOP10,.2,20

.5 mm

85 Cel

5 V

-40 Cel

18 V

DUAL

S-PDSO-G10

1.1 mm

3 mm

5 V

3 V

NOT SPECIFIED

NOT SPECIFIED

3 mm

12 V

6 V

5962R0724904TXC

Renesas Electronics

SWITCHING CONTROLLER

MILITARY

8

DFP

SQUARE

YES

UNSPECIFIED

1 A

1

MIL-PRF-38535

FLAT

PULSE WIDTH MODULATION

FLATPACK

1.27 mm

125 Cel

-55 Cel

DUAL

S-XDFP-F8

2.92 mm

6.475 mm

Qualified

9 V

6.475 mm

13.2 V

M62290FP

Renesas Electronics

SWITCHING CONTROLLER

OTHER

8

SOP

RECTANGULAR

YES

170 kHz

PLASTIC/EPOXY

.1 A

1

BIPOLAR

GULL WING

PULSE WIDTH MODULATION

SINGLE

SMALL OUTLINE

SOP8,.25

Switching Regulator or Controllers

1.27 mm

85 Cel

VOLTAGE-MODE

-20 Cel

DUAL

R-PDSO-G8

2.03 mm

4.4 mm

Not Qualified

12 V

6 V

4.85 mm

15 V

UPC1100C

Renesas Electronics

DUAL SWITCHING CONTROLLER

OTHER

16

DIP

RECTANGULAR

NO

500 kHz

PLASTIC/EPOXY

.025 A

1

BIPOLAR

THROUGH-HOLE

PULSE WIDTH MODULATION

SINGLE

IN-LINE

DIP16,.3

Switching Regulator or Controllers

2.54 mm

85 Cel

VOLTAGE-MODE

-20 Cel

TIN LEAD

DUAL

R-PDIP-T16

5.08 mm

7.62 mm

Not Qualified

6 V

3.6 V

e0

40 V

IS9-1845ASRH-QS9000

Renesas Electronics

SWITCHING CONTROLLER

AUTOMOTIVE

18

DFP

RECTANGULAR

YES

300k Rad(Si)

PLASTIC/EPOXY

1

BICMOS

FLAT

PULSE WIDTH MODULATION

FLATPACK

125 Cel

CURRENT-MODE

-50 Cel

DUAL

R-PDFP-F18

12 V

20 V

ZL6105ALAFTKR5619

Renesas Electronics

SWITCHING CONTROLLER

IS7-1845ASRH-QS9000

Renesas Electronics

SWITCHING CONTROLLER

AUTOMOTIVE

8

DIP

RECTANGULAR

NO

300k Rad(Si)

CERAMIC, METAL-SEALED COFIRED

1

BICMOS

THROUGH-HOLE

PULSE WIDTH MODULATION

IN-LINE

125 Cel

CURRENT-MODE

-50 Cel

DUAL

R-CDIP-T8

12 V

20 V

EL7515IYZ

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

10

TSSOP

SQUARE

YES

1200 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

5 V

BOOST

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

TSSOP10,.2,20

.5 mm

85 Cel

4.5 V

-40 Cel

MATTE TIN

17 V

DUAL

S-PDSO-G10

1.1 mm

3 mm

5 V

1.8 V

e3

3 mm

12 V

13.2 V

EL7512CYZ-T7

Renesas Electronics

SWITCHING REGULATOR

INDUSTRIAL

10

TSSOP

SQUARE

YES

1200 kHz

PLASTIC/EPOXY

1.5 A

1

GULL WING

PULSE WIDTH MODULATION

5 V

BOOST

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

TSSOP10,.2,20

.5 mm

85 Cel

5 V

-40 Cel

MATTE TIN

18 V

DUAL

S-PDSO-G10

1.1 mm

3 mm

5 V

3 V

e3

3 mm

12 V

6 V

HIP6304CB-T

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

16

SOP

RECTANGULAR

YES

305 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE

1.27 mm

70 Cel

0 Cel

DUAL

R-PDSO-G16

1.75 mm

3.9 mm

5 V

4.75 V

9.9 mm

5.25 V

RAA228228GNP#MA0

Renesas Electronics

SWITCHING CONTROLLER

MATTE TIN

3

e3

HIP6012CV

Renesas Electronics

SWITCHING CONTROLLER

COMMERCIAL

14

TSSOP

RECTANGULAR

YES

200 kHz

PLASTIC/EPOXY

1

GULL WING

PULSE WIDTH MODULATION

BUCK

SMALL OUTLINE, THIN PROFILE, SHRINK PITCH

.65 mm

70 Cel

VOLTAGE-MODE

0 Cel

DUAL

R-PDSO-G14

1.2 mm

4.4 mm

12 V

10.8 V

5 mm

13.2 V

HA16108P-E

Renesas Electronics

SWITCHING CONTROLLER

OTHER

16

DIP

RECTANGULAR

NO

600 kHz

PLASTIC/EPOXY

2 A

1

THROUGH-HOLE

PULSE WIDTH MODULATION

SINGLE

IN-LINE

2.54 mm

85 Cel

VOLTAGE-MODE

-20 Cel

NICKEL PALLADIUM GOLD

DUAL

R-PDIP-T16

1

5.06 mm

7.62 mm

Not Qualified

18 V

12 V

e4

19.2 mm

30 V

M62273GP

Renesas Electronics

SWITCHING CONTROLLER

OTHER

5

LSSOP

RECTANGULAR

YES

160 kHz

PLASTIC/EPOXY

.1 A

1

GULL WING

PULSE WIDTH MODULATION

SINGLE

SMALL OUTLINE, LOW PROFILE, SHRINK PITCH

.95 mm

85 Cel

-20 Cel

DUAL

R-PDSO-G5

1.3 mm

1.6 mm

Not Qualified

5 V

4 V

2.9 mm

2.4 V

15 V

RAA230153GSB#YK0

Renesas Electronics

SWITCHING REGULATOR

Switching Regulators & Controllers

Switching regulators and controllers are electronic devices used to regulate the output voltage and current of power supplies. They operate by rapidly switching a power supply circuit between on and off states, resulting in a high-frequency waveform that can be filtered and smoothed to produce a stable output voltage.

Switching regulators and controllers offer several advantages over traditional linear regulators, including higher efficiency and the ability to handle a wider range of input voltages. They are commonly used in applications such as power supplies for computers, LED lighting, and motor control.

Switching regulators and controllers come in a variety of forms, including step-up (boost), step-down (buck), and step-up/down (buck-boost) configurations. They may be designed as integrated circuits (ICs) or as standalone modules.

Switching regulators and controllers typically include feedback control circuits to adjust the output voltage and current, as well as protection circuits to prevent overvoltage, overcurrent, and overtemperature conditions. They may also include features such as soft-start to reduce inrush currents and synchronization with external clock signals.