TEA1553T_1

© NXP B.V. 2007. All rights reserved.

Product data sheet

Rev. 01 — 3 July 2007

8 of 27

NXP Semiconductors

TEA1553T

GreenChip II SMPS control IC

7.5 VCO adjust

The VCOADJ pin can be used to set the VCO operation point. As soon as the peak

voltage on the sense resistor is controlled below half the voltage on the VCOADJ pin

somewhat higher due to switch-off delay, see Figure 8.) The frequency reduction will stop

A current of typically 10

µA flows out of the VCOADJ pin, enabling the VCO operation

point to be set with a single resistor. When a more low-ohmic connection is desired (e.g.

due to noise), a voltage divider can be made from the VCC5V pin (see Figure 7).

Fig 7.

Implementation of STDBY and cycle skipping functionality

CTRL

OSCILLATOR

V

I

× 2

Vx

1.5 V

− VCTRL

CURRENT COMPARATOR

DRIVER

5 V

DRIVER

ISENSE

VCC5V

VCOADJ

014aaa006