tea1553t NXP Semiconductors, tea1553t Datasheet - Page 6

• Manufacturer Part Number: tea1553t
• Description: Tea1553t Greenchip Ii Smps Control Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1553T_1
Product data sheet
7.1 Start-up, mains enabling operation level and undervoltage lock-out
7.2 Supply management
The next converter stroke is started only after demagnetization of the transformer current
(zero current switching), while the drain voltage has reached the lowest voltage to prevent
switching losses (green function). The primary resonant circuit of primary inductance and
drain capacitor ensures this quasi-resonant operation. The design can be optimized in
such a way that zero voltage switching can be achieved over almost the whole of the
universal mains range.
To prevent very high frequency operation at lower loads, the quasi-resonant operation
changes smoothly in fixed frequency Pulse Width Modulation (PWM) control.
At low power levels, the frequency is controlled via the Voltage Controlled Oscillator
(VCO), down to a minimum of about 25 kHz.
At very low power levels (standby), a cycle skipping mode will be activated.
Initially, the IC is self-supplying from the rectified mains voltage via pin DRAIN. Supply
capacitor C
higher, depending on the drain voltage. Once the drain voltage exceeds V
(mains-dependent operation-enabling voltage), the start-up current source will continue
charging capacitor C
power converter as soon as the voltage on pin V
is taken over by the auxiliary winding as soon as the output voltage reaches its intended
level and the IC supply from the mains voltage is subsequently stopped for high efficiency
operation (green function).
The moment the voltage on pin V
level, the IC stops switching and enters a safe restart from the rectified mains voltage.
Inhibiting the auxiliary supply by external means causes the converter to operate in a
stable, well defined burst mode. (See
All (internal) reference voltages are derived from a temperature compensated, on-chip
band gap circuit.
Fig 4. Multi mode operation
VCC
is charged by the internal start-up current source to a level of about 4 V or
VCC
125 kHz
Rev. 01 — 3 July 2007
25 kHz
(switch S1 will be opened); see
f
VCO
CC
drops below the V
Figure 14
FIXED
CC
and
quasi-resonant
passes the V
Figure
th(UVLO)
Figure
GreenChip II SMPS control IC
014aaa002
15).
POWER
(undervoltage lock-out)
startup
1. The IC will activate the
TEA1553T
level. The IC supply
© NXP B.V. 2007. All rights reserved.
mains(oper)(en)
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