TEA1507P View Datasheet(PDF) - Philips Electronics
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TEA1507P Datasheet PDF : 20 Pages
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Philips Semiconductors
GreenChip™II SMPS control IC
Preliminary specification
TEA1507
PINNING
SYMBOL PIN
DESCRIPTION
VCC
GND
1 supply voltage
2 ground
CTRL
3 control input
DEM
4 input from auxiliary winding for
demagnetization timing, OVP and OPP
Isense
DRIVER
5 programmable current sense input
6 gate driver output
HVS
7 high voltage safety spacer, not
connected
DRAIN
8 drain of external MOS switch, input for
start-up current and valley sensing
handbook, halfpage
VCC 1
GND 2
CTRL 3
TEA1507
8 DRAIN
7 HVS
6 DRIVER
DEM 4
5 Isense
MGU231
Fig.3 Pin configuration.
FUNCTIONAL DESCRIPTION
The TEA1507 is the controller of a compact flyback
converter, with the IC situated at the primary side. An
auxiliary winding of the transformer provides
demagnetization detection and powers the IC after
start-up.
The TEA1507 operates in multi modes.
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 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
about 6 kHz. Typically, 3 Watts can be achieved for a
75 W converter with an output power of 100 mW.
Start-up, mains enabling operation level and
undervoltage lock out (see Figs. 10 and 11)
Initially, the IC is self supplying from the rectified mains
voltage via pin DRAIN. Supply capacitor CVCC is charged
by the internal start-up current source to a level of about
4 V or higher, depending on the drain voltage. Once the
drain voltage exceeds the M-level (mains-dependent
operation-enabling level), the start-up current source will
continue charging capacitor CVCC (switch S1 will be
opened), see Fig.2. The IC will activate the power
converter as soon as the voltage on pin VCC passes the
VCC(start) level. The IC supply 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 VCC drops below the
VUVLO (undervoltage lock out) 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.
Supply management
All (internal) reference voltages are derived from a
temperature compensated, on-chip band gap circuit.
f
handbook, halfpage
VCO
175 kHz
fixed
MGU232
quasi resonant
6 kHz
power
Fig.4 Multi mode operation.
2000 Dec 05
5
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