tea1738t NXP Semiconductors, tea1738t Datasheet - Page 7

• Manufacturer Part Number: tea1738t
• Description: Tea1738t; Tea1738lt Greenchip Smps Control Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1738T_TEA1738LT
Product data sheet
7.6 Protection input (PROTECT PIN)
7.7 Duty cycle control (CTRL pin)
7.8 Slope compensation (CTRL pin)
7.9 Overpower timer (OPTIMER pin)
Pin PROTECT is a general purpose input pin, which can be used to switch off the
converter (latched protection). The converter is stopped when the voltage on this pin is
pulled above V
current of 32 μA (typical) flows out of the chip when the pin voltage is at the
V
is at the V
The PROTECT input can be used to create an overvoltage detection and OTP functions.
A small capacitor can be connected to the pin if the protections on this pin are not used.
An internal clamp of 4.1 V (typical) protects this pin from excessive voltages.
The output power of the converter is regulated by the CTRL pin. This pin is connected to
an internal 5.4 V supply using an internal 7 kΩ resistor.
The CTRL pin voltage sets the peak current which is measured via pin ISENSE
(see
(see
After 8 consecutive converter strokes at maximum duty cycle the restart protection is
activated. Typically this occurs when the mains input voltage is removed.
A slope compensation circuit is integrated in the IC for CCM. Slope compensation
guarantees stable operation for duty cycles greater than 50 %.
If the OPTIMER pin is connected to capacitor C4 (see
situation is allowed. V
400 mV, the I
voltage on the OPTIMER pin reaches the V
OverPower Protection (OPP) is triggered (see
det(L)(PROTECT)
Section
Section
det(H)(PROTECT)
7.11). At low and medium output power the switching frequency is reduced
7.13). The maximum duty cycle is limited to 80 % (typical).
IO(OPTIMER)
det(H)(PROTECT)
All information provided in this document is subject to legal disclaimers.
level. A current of 107 μA (typical) flows into the chip when the pin voltage
ctrl(Ipeak)
Rev. 2 — 14 January 2011
current (11 μA typical) is sourced from the OPTIMER pin. If the
level.
(0.8 V typical) or below V
(see
Figure
TEA1738T; TEA1738LT
1) is set by pin CTRL. When V
prot(OPTIMER)
Figure
5).
Figure
det(L)(PROTECT)
voltage (2.5 V typical) the
GreenChip SMPS control IC
3), a temporary overload
(0.5 V typical). A
© NXP B.V. 2011. All rights reserved.
ctrl(Ipeak)
is above
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