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TEA1738T/N1,118

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21
TEA1738T_TEA1738LT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 2 — 14 January 2011 4 of 21
NXP Semiconductors
TEA1738T; TEA1738LT
GreenChip SMPS control IC
6. Pinning information
6.1 Pinning
6.2 Pin description
Fig 2. Pin configuration: TEA1738(L) (SOT96-1)
TEA1738T
TEA1738LT
VCC OPTIMER
GND CTRL
DRIVER
PROTECT
ISENSE VINSENSE
001aan168
1
2
3
4
6
5
8
7
Table 2. Pin description
Symbol Pin Description
VCC 1 supply voltage
GND 2 ground
DRIVER 3 gate driver output
ISENSE 4 current sense input
VINSENSE 5 input voltage protection input
PROTECT 6 general purpose protection input
CTRL 7 control input
OPTIMER 8 overpower and restart timer
TEA1738T_TEA1738LT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 2 — 14 January 2011 5 of 21
NXP Semiconductors
TEA1738T; TEA1738LT
GreenChip SMPS control IC
7. Functional description
7.1 General control
The TEA1738(L) contains a flyback circuit controller, a typical configuration of which is
shown in Figure 3
.
7.2 Start-up and UnderVoltage LockOut (UVLO)
Initially, the capacitor on the VCC pin is charged from the high voltage mains via resistor
R3.
If V
CC
is lower than V
startup
, the IC current consumption is low (10 μA typical). When V
CC
reaches V
startup
the IC first waits for pin VINSENSE to reach the V
start(VINSENSE)
voltage
and for pin PROTECT to reach the V
det(L)(PROTECT)
voltage. When both levels are
reached, the IC charges the ISENSE pin to the V
start(soft)
level and starts switching. In a
typical application the supply voltage is taken over by the auxiliary winding of the
transformer.
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
TEA1738(L) 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 μA 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 TEA1738(L) immediately enters Power-down
mode. The VCC pin is clamped to a voltage just above the latch protection reset voltage
(V
rst(latch)
+1V).
Fig 3. Typical configuration
001aan16
9
TEA1738T
TEA1738LT
5
6
7
8
4
3
2
1
R1
R2
R3
R4
O1
C4
R8
C5
R9
C1
D1
C2
C6
D2
R6
R10
D3
T1
C7
Z1
O1
S1
Θ
DRIVER
GND
VCC
ISENSE
VINSENSE
PROTECT
CTRL
OPTIMER
TEA1738T_TEA1738LT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 2 — 14 January 2011 6 of 21
NXP Semiconductors
TEA1738T; TEA1738LT
GreenChip SMPS control IC
When the voltage on pin VCC drops below the V
th(UVLO)
level during normal operation, the
controller stops switching and the TEA1738T enters Restart mode. In Restart mode the
driver output is disabled and the VCC pin voltage is recharged via resistor R3 to the
rectified mains voltage. For the TEA1738LT a VCC undervoltage, which does not occur
during a start-up event, latches the IC in an off-state.
7.3 Supply management
All internal reference voltages are derived from a temperature compensated on-chip band
gap circuit. Internal reference currents are derived from a trimmed and temperature
compensated current reference circuit.
7.4 OverVoltage Protection (VCC pin)
An OVP circuit is connected to the VCC pin. After 8 consecutive OVP cycles the IC
triggers the latched protection. When V
CC
drops below the V
th(OVP)
voltage before count=8
is reached, the counter is reset to zero.
If a lower overvoltage protection level is needed, a Zener diode can be connected
between the VCC pin and the PROTECT pin.
7.5 Input voltage detection (VINSENSE pin)
In a typical application the mains input voltage can be detected by the VINSENSE pin.
Switching does not take place until the voltage on VINSENSE has reached the
V
start(VINSENSE)
voltage (0.94 V typical).
When during operation the VINSENSE voltage drops below V
det(L)(VINSENSE)
(0.72 V typical), the converter stops switching and performs a restart.
An internal clamp of 5.2 V (typical) protects this pin from excessive voltages.
Fig 4. Start-up sequence, normal operation and restart sequence
001aan170
starting
converter
charging VCC
capacitor
normal
operation
protection
(power-down)
soft start
V
CC
ISENSE
VINSENSE
PROTECT
OPTIMER
V
O
restart
soft start
V
startup
V
th(UVLO)
V
det(H)(PROTECT)
V
start(VINSENSE)
V
det(L)(VINSENSE)
V
det(L)(PROTECT)
4.5 V
1.2 V
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21

TEA1738T/N1,118

Mfr. #:
Buy TEA1738T/N1,118
Manufacturer:
NXP Semiconductors
Description:
Switching Controllers GREENCHIP SMPS CONTROL IC
Lifecycle:
New from this manufacturer.
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