BD3531F

3/15

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TSZ22111・15・001

TSZ02201-0J2J0A900950-1-2

02.Nov.2015 Rev.001

Description of Blocks

– continued

6.

VTT

This is the output pin for the DDR memory termination voltage and it has a sink/source current capability of ±1.5A. VTT

voltage tracks the voltage at VDDQ pin divided in half. The output is turned OFF when EN pin is “Low” or when either

the VCC UVLO or the thermal shutdown protection function is activated.

Always connect a capacitor to VTT pin for loop gain and phase compensation and for reduction in output voltage

variation in the event of sudden load change. Be careful in choosing the capacitor as insufficient capacitance may

cause oscillation and high ESR (Equivalent Series Resistance) may result in increased output voltage variation during

a sudden change in load. Using a low-ESR ceramic capacitor, however, may reduce the loop gain and phase margin

and may caus

e oscillation. But this effect can be lessened by connecting a resistor in series with the capacitor. A 220μF

functional polymer capacitor (OS-CON, POS-CAP, NEO-CAP) is recommended, though ambient temperature and

other conditions should also be considered.

7.

EN

A “High” input of 2.0V or higher to EN turns ON the VTT output. A “Low” input of 0.8V or less, on the other hand, turns

VTT to a Hi-

Z state. With a “Low” EN input, however, the VREF output remains ON, provided that sufficient VCC and

VDDQ voltages have been established.

Absolute Maximum Ratings

Parameter

Symbol

Limit

Unit

Input Voltage

V

EN Input Voltage

V

Termination Input Voltage

V

VDDQ Reference Voltage

V

Output Current

1.5

A

Power Dissipation1

Pd1

W

Power Dissipation2

Pd2

W

Operating Temperature Range

Topr

-10 to +100

°C

Storage Temperature Range

Tstg

-55 to+150

°C

Maximum Junction Temperature

Tjmax

+150

°C

(Note 1) Should not exceed Pd.

(Note 2) Derate by 4.48mW/°C for Ta over 25°C (With no heat sink).

(Note 3) Derate by 5.52mW/°C for Ta over 25°C (When mounted on a board 70mm x 70mm x 1.6mm Glass-epoxyPCB).

Caution: Operating the IC over the absolute maximum ratings may damage the IC. In addition, it is impossible to predict all destructive situations such as

short-circuit modes, open circuit modes, etc. Therefore, it is important to consider circuit protection measures, like adding a fuse, in case the IC is operated in a

special mode exceeding the absolute maximum ratings.

Recommended Operating Conditions (Ta=25°C)

Parameter

Symbol

Min

Max

Unit

Input Voltage

4.5

5.5

V

Termination Input Voltage

1.0

5.5

V

EN Input Voltage

-0.3

+5.5

V