Philips Semiconductors
Product specification
GreenChip™II SMPS control IC
FEATURES
Distinctive features
•
Universal mains supply operation (70 to 276 V AC)
•
High level of integration, giving a very low external
component count.
Green features
•
Valley or zero voltage switching for minimum switching
losses
•
Efficient quasi-resonant operation at high power levels
•
Frequency reduction at low power standby for improved
system efficiency (<3 W)
•
Cycle skipping mode at very low loads; P
i
< 300 mW at
no-load operation for a typical adapter application
•
On-chip start-up current source
•
Standby indication pin to indicate low output power
consumption.
Protection features
•
Safe restart mode for system fault conditions
•
Continuous mode protection by means of
demagnetization detection (zero switch-on current)
•
Accurate and adjustable overvoltage protection
(latched)
•
Short winding protection
•
Undervoltage protection (foldback during overload)
•
Overtemperature protection (latched)
•
Low and adjustable overcurrent protection trip level
•
Soft (re)start
•
Mains voltage-dependent operation-enabling level
•
General purpose input for lock protection.
APPLICATIONS
TEA1654
Typical application areas are adapters and chargers (e.g.
for laptops, camcorders and printers) and all applications
that demand an efficient and cost-effective solution up to
250 W.
GENERAL DESCRIPTION
The GreenChip™
(1)
II is the second generation of green
Switched Mode Power Supply (SMPS) control ICs
operating directly from the rectified universal mains. A high
level of integration leads to a cost effective power supply
with a very low number of external components.
The special built-in green functions allow the efficiency to
be optimum at all power levels. This holds for
quasi-resonant operation at high power levels, as well as
fixed frequency operation with valley switching at medium
power levels. At low power (standby) levels, the system
operates at reduced frequency and with valley detection.
The proprietary high voltage BCD800 process makes
direct start-up possible from the rectified mains voltage in
an effective and green way. A second low voltage
BICMOS IC is used for accurate, high speed protection
functions and control.
Highly efficient, reliable supplies can easily be designed
using the GreenChipII control IC.
(1) GreenChip™ is a trademark of Koninklijke Philips
Electronics N.V.
2003 May 12
2
Philips Semiconductors
Product specification
GreenChip™II SMPS control IC
PINNING
SYMBOL PIN
VCOadj
I
sense
STDBY
DRIVER
HVS
HVS
DRAIN
V
CC
n.c.
GND
V
CC(5V)
LOCK
CTRL
DEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
DESCRIPTION
VCO adjustment input
programmable current sense input
standby indication or control output
gate driver output
high voltage safety spacer, not
connected
high voltage safety spacer, not
connected
drain of external MOS switch, input for
start-up current and valley sensing
supply voltage
not connected
ground
5 V output
lock input
control input
input from auxiliary winding for
demagnetization timing, OVP and OPP
FUNCTIONAL DESCRIPTION
TEA1654
The TEA1654 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 TEA1654 operates in multi modes (see Fig.4).
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 complete
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 24 kHz.
Start-up, mains enabling operation level and
undervoltage lock-out
(see Figs 11 and 12)
Initially, the IC is self supplying from the rectified mains
voltage via pin DRAIN. Supply capacitor C
VCC
is charged
by the internal start-up current source to a level of
approximately 4 V (or higher, this is dependent on the
drain voltage/M-level). Once the drain voltage exceeds the
M-level (mains-dependent operation-enabling level), the
start-up current source will continue charging
capacitor C
VCC
(switch S1 will be opened); see Fig.2.
The IC will activate the power converter as soon as the
voltage on pin V
CC
passes the level V
CC(start)
. 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 V
CC
drops below the
undervoltage lock-out level V
UVLO
, 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 safe restart mode.
Supply management
handbook, halfpage
VCOadj 1
Isense 2
STDBY 3
DRIVER 4
HVS 5
HVS 6
DRAIN 7
MDB216
14 DEM
13 CTRL
12 LOCK
TEA1654T
11 VCC(5V)
10 GND
9
8
n.c.
VCC
Fig.3 Pin configuration.
All (internal) reference voltages are derived from a
temperature compensated, on-chip band gap circuit.
2003 May 12
5
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