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APPLICATION INFORMATION

Typical DDR Application Diagram

Inhibit

+

+

DDRII/

QDRII

PTH05010W

VDDQ I/O Memory

Inhibit

+

PTH05050Y

DDR Termination

+

2 ×

330 µF

2 ×

22 µF

2 ×

330 µF

2 ×

22 µF

+Sense

Margin ±

Auto-Track

VI

+VADJ

1 kΩ

1 kΩ

VI= 5V

220 µF

47 µF

470 µF

47 µF

5.51 kΩ

VO

+VREF

VI

UDG−05096

VTT

VTT = 0.9 V

VDDQ = 1.8 V

CAPACITOR RECOMMENDATIONS FOR THE PTH03060Y AND PTH05060Y DDR POWER

Input Capacitor

Output Capacitors

PTH03060Y

PTH05060Y, PTH12060Y

SLTS222A–MARCH 2004–REVISED OCTOBER 2005

MODULES (3.3-V/5-V OPTION)

The recommended input capacitor(s) is determined by the 330 µF(1) minimum capacitance and 300 mArms

minimum ripple current rating.

Ripple current and less than 160 mΩ equivalent series resistance (ESR) values are the major considerations,

along with temperature, when designing with different types of capacitors. Unlike polymer tantalum, regular

tantalum capacitors have a recommended minimum voltage rating of 2 × (maximum DC voltage + AC ripple).

This is standard practice to insure reliability.

For improved ripple reduction on the input bus, ceramic capacitors may be substituted for electrolytic types using

the minimum required capacitance.

For applications with load transients (sudden changes in load current), regulator response will benefit from

external output capacitance. The recommended output capacitance of 470 µF will allow the module to meet its

transient response specification (see Electrical Specifications table). For most applications, a high quality

computer-grade aluminum electrolytic capacitor is adequate. These capacitors provide decoupling over the

frequency range, 2 kHz to 150 kHz, and are suitable when ambient temperatures are above 0°C. For operation

below 0°C tantalum, ceramic or Os-Con type capacitors are recommended. When using one or more

non-ceramic capacitors, the calculated equivalent ESR should be no lower than 4 mΩ (7 mΩ using the

manufacturer's maximum ESR for a single capacitor). A list of preferred low-ESR type capacitors are identified in

Table 1.

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