1.
General description
The TEA1622P is a Switched Mode Power Supply (SMPS) controller IC that operates
directly from the rectified universal mains. It is implemented in the high voltage EZ-HVTM
SOI process, combined with a low voltage BICMOS process.
The device includes a high voltage power switch and a circuit for start-up directly from the
rectified mains voltage. A dedicated circuit for valley switching is built in, which makes a
very efficient slim-line electronic power-plug concept possible.
In its most basic version of application, the TEA1622P acts as a voltage source. Here, no
additional secondary electronics are required. A combined voltage and current source can
be realized with minimum costs for external components. Implementation of the
TEA1622P renders an efficient and low cost power supply system.
2.
Features
s
Designed for general purpose supplies
s
Integrated power switch: 12
and 650 V
s
Operates from universal AC mains supplies: 80 V to 276 V
s
Adjustable frequency for flexible design
s
RC oscillator for load insensitive regulation loop constant
s
Valley switching for minimum switch-on loss
s
Frequency reduction at low power output for low standby power: <100 mW
s
Adjustable overcurrent protection
s
Undervoltage protection
s
Temperature protection
s
Short winding protection
s
Safe restart mode for system fault conditions
s
Simple application with both primary and secondary (opto) feedback
s
Available in 8-pin DIP package.
3.
Applications
TEA1622P
STARplug
TM
Rev. 01 -- 17 March 2004
Product data sheet
s
Adapters
s
VCD
s
Set-Top Box (STB)
s
CD(R)
s
DVD
s
PC Silverbox standby SMPS.
9397 750 12578
Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data sheet
Rev. 01 -- 17 March 2004
2 of 16
Philips Semiconductors
TEA1622P
STARplug
TM
4.
Quick reference data
5.
Ordering information
Table 1:
Quick reference data
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
V
CC(max)
maximum supply voltage
-
-
40
V
V
DRAIN(max)
maximum voltage at pin
DRAIN
T
j
> 0
C
-
-
650
V
I
DRAIN
supply current drawn from
pin DRAIN
no auxiliary supply
-
0.5
-
mA
R
DSon
drain-source on-state
resistance
I
SOURCE
=
-
0.25 A
T
j
= 25
C
-
12
13.8
T
j
= 100
C
-
17
19.6
f
osc
oscillator frequency range
10
-
200
kHz
T
amb
ambient temperature
-
20
-
+85
C
Table 2:
Ordering information
Type number
Package
Name
Description
Version
TEA1622P
DIP8
plastic dual in-line package; 8 leads (300 mil)
SOT97-1
9397 750 12578
Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data sheet
Rev. 01 -- 17 March 2004
3 of 16
Philips Semiconductors
TEA1622P
STARplug
TM
6.
Block diagram
7.
Pinning information
7.1 Pinning
Fig 1.
Block diagram.
col009
PROTECTION
LOGIC
LOGIC
SUPPLY
TEA1622P
VALLEY
POWER-UP
RESET
THERMAL
SHUTDOWN
OSCILLATOR
PWM
stop
low frequency
100 mV
0.75 V
0.5 V
blank
short winding
overcurrent
10x
2.5 V
f
1.8
U
1
2
3
4
8
7
6
5
DRAIN
n.c.
GND
SOURCE
AUX
REG
RC
V
CC
Fig 2.
Pin configuration.
TEA1622P
V
CC
DRAIN
GND
n.c.
RC
SOURCE
REG
AUX
001aaa309
1
2
3
4
6
5
8
7
9397 750 12578
Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data sheet
Rev. 01 -- 17 March 2004
4 of 16
Philips Semiconductors
TEA1622P
STARplug
TM
7.2 Pin description
8.
Functional description
The TEA1622P is the heart of a compact flyback converter, with the IC placed at the
primary side. The auxiliary winding of the transformer can be used for indirect feedback to
control the isolated output. This additional winding also powers the IC. A more accurate
control of the output voltage and/or current can be implemented with an additional
secondary sensing circuit and optocoupler feedback.
The TEA1622P uses voltage mode control. The frequency is determined by the maximum
transformer demagnetizing time and the time of the oscillator. In the first case, the
converter operates in the Self Oscillating Power Supply (SOPS) mode. In the latter case, it
operates at a constant frequency, which can be adjusted with external components R
RC
and C
RC
. This mode is called Pulse Width Modulation (PWM). Furthermore, a primary
stroke is started only in a valley of the secondary ringing. This valley switching principle
minimizes capacitive switch-on losses.
8.1 Start-up and undervoltage lock-out
Initially, the IC is self supplying from the rectified mains voltage. The IC starts switching as
soon as the voltage on pin V
CC
passes the V
CC(start)
level. The supply is taken over by the
auxiliary winding of the transformer as soon as V
CC
is high enough and the supply from
the line is stopped for high efficiency operation.
As soon as the voltage on pin V
CC
drops below the V
CC(stop)
level, the IC stops switching
and restarts from the rectified mains voltage.
8.2 Oscillator
The frequency of the oscillator is set by the external resistor and capacitor on pin RC. The
external capacitor is charged rapidly to the V
RC(max)
level and, starting from a new primary
stroke, it discharges to the V
RC(min)
level. Because the discharge is exponential, the
relative sensitivity of the duty factor to the regulation voltage at low duty factor is almost
equal to the sensitivity at high duty factors. This results in a more constant gain over the
duty factor range compared to PWM systems with a linear sawtooth oscillator. Stable
operation at low duty factors is easily realized. For high efficiency, the frequency is
reduced as soon as the duty factor drops below a certain value. This is accomplished by
increasing the oscillator charge time.
Table 3:
Pin description
Symbol
Pin
Description
V
CC
1
supply voltage
GND
2
ground
RC
3
frequency setting
REG
4
regulation input
AUX
5
input for voltage from auxiliary winding for timing (demagnetization)
SOURCE
6
source of internal MOS switch
n.c.
7
not connected
DRAIN
8
drain of internal MOS switch; input for start-up current and valley sensing
9397 750 12578
Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data sheet
Rev. 01 -- 17 March 2004
5 of 16
Philips Semiconductors
TEA1622P
STARplug
TM
To ensure that the capacitor can be charged within the charge time, the value of the
oscillator capacitor should be limited to approximately 1 nF.
8.3 Duty factor control
The duty factor is controlled by the internal regulation voltage and the oscillator signal on
pin RC. The internal regulation voltage is equal to the external regulation voltage (minus
2.5 V) multiplied by the gain of the error amplifier (typical 20 dB or 10
).
The minimum duty factor of the switched mode power supply is 0 %. The maximum duty
factor is set to 75 % (typical value at 100 kHz oscillation frequency).
8.4 Valley switching
A new cycle is started at the primary stroke when the switch is switched on (see
Figure 3
).
After a certain time (determined by the RC oscillator voltage and the internal regulation
level), the switch is turned off and the secondary stroke starts. The internal regulation
level is determined by the voltage on pin REG. After the secondary stroke, the drain
voltage shows an oscillation with a frequency of approximately
Where:
L
p
is the primary self inductance on the drain node
C
p
is the parasitic capacitance on the drain node.
As soon as the oscillator voltage is high again and the secondary stroke has ended, the
circuit waits for a low drain voltage before starting a new primary stroke.
The primary stroke starts some time before the actual valley at low ringing frequencies,
and some time after the actual valley at high ringing frequencies.
Figure 4
shows a typical
curve for a reflected voltage N
V
o
of 80 V. This voltage is the output voltage V
o
(see
Figure 5
) transferred to the primary side of the transformer with the factor N (determined
by the turns ratio of the transformer).
Figure 4
shows that the system switches exactly at
minimum drain voltage for ringing frequencies of 480 kHz, thus reducing the switch-on
losses to a minimum. At 200 kHz, the next primary stroke is started at 33
before the
valley. The switch-on losses are still reduced significantly.
1
2
L
p
C
p
------------------------------
PDF 
ZIP