TEA1506AP Philips Semiconductors, TEA1506AP Datasheet - Page 6

• Manufacturer Part Number: TEA1506AP
• Description: GreenChip SMPS control IC
• Manufacturer: Philips Semiconductors

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DataSheet
Philips Semiconductors
FUNCTIONAL DESCRIPTION
The TEA1506 is the controller of a compact flyback
converter, and is situated at the primary side. An auxiliary
winding of the transformer provides demagnetization
detection and powers the IC after start-up.
The TEA1506 can operate in multi modes (see Fig.5).
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 the 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 reached over almost the universal mains
range.
To prevent very high frequency operation at lower loads,
the quasi-resonant operation changes smoothly in fixed
frequency PWM control.
At very low power (standby) levels, the frequency is
controlled down, via the VCO, to a minimum frequency of
approximately 25 kHz.
Start-up and undervoltage lock-out
Initially the IC is in the save restart mode. As long as V
is below the V
zero.
The IC will activate the converter as soon as the voltage on
pin V
The IC supply is taken over by the auxiliary winding as
soon as the output voltage reaches its intended level.
2003 Sep 09
4
handbook, halfpage
U
GreenChip II SMPS control IC
.com
CC
passes the V
(kHz)
175
f
25
CC(start)
Fig.5 Multi modes operation.
VCO
CC(start)
level, the supply current is nearly
fixed
level.
quasi resonant
MGU508
P (W)
DataSheet4U.com
CC
6
The moment the voltage on pin V
undervoltage lock-out level, the IC stops switching and
re-enters the safe restart mode.
Supply management
All (internal) reference voltages are derived from a
temperature compensated, on-chip band gap circuit.
Current mode control
Current mode control is used for its good line regulation
behaviour.
The ‘on-time’ is controlled by the internally inverted control
voltage, which is compared with the primary current
information. The primary current is sensed across an
external resistor. The driver output is latched in the logic,
preventing multiple switch-on.
The internal control voltage is inversely proportional to the
external control pin voltage, with an offset of 1.5 V. This
means that a voltage range from 1 to 1.5 V on pin CTRL
will result in an internal control voltage range from
0.5 to 0 V (a high external control voltage results in a low
duty cycle).
Oscillator
The maximum fixed frequency of the oscillator is set by an
internal current source and capacitor. The maximum
frequency is reduced once the control voltage enters the
VCO control window. Then, the maximum frequency
changes linearly with the control voltage until the minimum
frequency is reached (see Figs 6 and 7).
handbook, halfpage
Fig.6 V
V sense(max)
0.52 V
sense(max)
TEA1506P; TEA1506AP;
TEA1506T; TEA1506AT
(typ)
1 V
voltage as function of V
CC
1.5 V
(typ)
drops below the
Product specification
V CTRL
MGU233
CTRL
.