TEA1738FT View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
Manufacturer
TEA1738FT Datasheet PDF : 20 Pages
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NXP Semiconductors
TEA1738FT
GreenChip SMPS control IC
7. Functional description
7.1 General control
The TEA1738FT contains a flyback circuit controller, a typical configuration of which is
shown in Figure 3.
C1
R1
D1
C2
R2
R4
Θ
O1
Fig 3. Typical configuration
D3
T1
C7
VINSENSE 5
4 ISENSE
PROTECT 6
3 DRIVER
CTRL
TEA1738FT
7
2
GND
OPTIMER
8
1 VCC
C4
R8
C5
VCC
S1
R10
R6
C6
R9
Z1
O1
014aab291
7.2 Start-up and UnderVoltage LockOut (UVLO)
In a typical application the VCC supply voltage is provided by an additional standby power
supply.
If VCC is lower than Vstartup, the IC current consumption is low (10 A typical). When VCC
reaches Vstartup the IC first waits for pin VINSENSE to reach the Vstart(VINSENSE) voltage
and for pin PROTECT to reach the Vdet(L)(PROTECT) voltage. When both levels are
reached, the IC charges the ISENSE pin to the Vstart(soft) level and starts switching.
If a protection is triggered the controller stops switching. Depending on the protection
triggered it either causes a restart or latches the converter to an off-state.
A restart caused by a protection rapidly charges the OPTIMER pin to 4.5 V (typical). The
TEA1738FT enters Power-down mode until the OPTIMER pin discharges down to
1.2 V (typical). In Power-down mode, the IC consumes a very low supply current
(10 A typical) and the VCC pin is clamped at 22 V (typical) by an internal clamp circuit.
When the voltage on pin OPTIMER drops below 1.2 V (typical) and the VCC pin voltage is
above the VCC start-up voltage (see Figure 4), the IC restarts.
When a latched protection is triggered, the TEA1738FT immediately enters Power-down
mode. The VCC pin is clamped to a voltage just above the latch protection reset voltage
(Vrst(latch) + 1 V).
TEA1738FT
Preliminary data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 30 December 2010
© NXP B.V. 2010. All rights reserved.
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