1

2

3

6

5

4

R

LOAD

0.47 F

m

+5 V

GND_F

Contact and Trace Resistance

GND_S

ENABLE

OUT_F

OUT_S

IN

REF32xx

REF3212-EP, REF3220-EP, REF3225-EP

REF3230-EP, REF3233-EP, REF3240-EP

SBVS078B

– OCTOBER 2006 – REVISED AUGUST 2011

www.ti.com

Load Regulation

Load regulation is defined as the change in output voltage as a result of changes in load current. The load

regulation of the REF32xx is measured using force and sense contacts, as shown in Figure 7. The force and

sense lines can be used to effectively eliminate the impact of contact and trace resistance, resulting in accurate

voltage at the load. By connecting the force and sense lines at the load, the REF32xx compensates for the

contact and trace resistances because it measures and adjusts the voltage actually delivered at the load.

Figure 7. Accurate Load Regulation of REF32xx

The GND_S pin is connected to the internal ground of the device through ESD protection diodes. Because of

that connection, the maximum differential voltage between the GND_S and GND_F pins must be kept below

200mV to prevent these dioes from unintentionally turning on.

Load Capacitance Guidelines

The REF32xx series is designed to be stable with most capacitive loads. Common load capacitance values

range between 1

μF and 47 μF. To minimize noise and provide specified performance, all models will benefit

from an ESR value above 1

Ω with capacitive loads higher than 10 μF. However, the REF3212 must have an

ESR value above 1

Ω with capacitive loads higher than 10 μF to avoid oscillation.

14

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Copyright

© 2006–2011, Texas Instruments Incorporated

Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP