NXP TEA1520P, TEA1520T, TEA1521P, TEA1521T, TEA1522P Schematic [ru]

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1. General description

The TEA152x family STARplug 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-HV SOI process, combined with a low-voltage Bipolar Complementary
Metal-Oxide Semiconductor (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
In its most basic version of application, the TEA152x family 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 TEA152x family renders an efficient and low cost power supply system.

2. Features and benefits

Designed for general purpose supplies up to 30 W
Integrated power switch:
Æ TEA1520x: 48 Ω; 650 V
Æ TEA1521x: 24 Ω; 650 V
Æ TEA1522x: 12 Ω; 650 V
Æ TEA1523P: 6.5 Ω; 650 V
Operates from universal AC mains supplies (80 V to 276 V)
Adjustable frequency for flexible design
RC oscillator for load insensitive regulation loop constant
Valley switching for minimum switch-on loss
Frequency reduction at low power output makes low standby power possible
(< 100 mW)
Adjustable overcurrent protection
Undervoltage protection
Temperature protection
Short-circuit winding protectio n
Simple application with both primary and secondary (opto) feedback
Available in DIP8 and SO14 packages
TEA152x
SMPS ICs for low-power systems
Rev. 04 — 14 September 2010 Product data sheet
TEA152X All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 04 — 14 September 2010 2 of 20
NXP Semiconductors
TEA152x
SMPS ICs for low-power systems

3. Applications

Chargers
Adapters
Set-Top Box (STB)
DVD
CD(R)
TV/monitor standby supplies
PC peripherals
Microcontroller supplies in home applications and small portable equipment, etc.

4. Quick reference data

Table 1. Quick reference data
Symbol Parameter Conditions Min Typ Max Unit
V
drain
voltage on pin DRAIN T
j
>0°C 0.4 - +650 V
R
DSon
drain-source on-state
resistance
TEA1520x I
source
= 0.06 A
T
j
=25°C - 48 55.2 Ω
T
j
= 100 °C - 68 78.2 Ω
TEA1521x I
source
= 0.125 A
T
j
=25°C - 24 27.6 Ω
T
j
= 100 °C - 34 39.1 Ω
TEA1522x I
source
= 0.25 A
T
j
=25°C - 12 13.8 Ω
T
j
= 100 °C - 17 19.6 Ω
TEA1523P I
source
= 0.50 A
T
j
=25°C-6.57.5Ω
T
j
= 100 °C - 9.0 10.0 Ω
V
CC
supply voltage continuous 0.4 - +40 V
f
osc
oscillator frequency 10 100 200 kHz
I
drain
current on pin DRAIN V
drain
>60V;
no auxiliary supply
-1.52mA
TEA152X All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 04 — 14 September 2010 3 of 20
NXP Semiconductors
TEA152x
SMPS ICs for low-power systems

5. Ordering information

6. Block diagram

Table 2. Ordering information
Type number Package
Name Description Version
TEA1520P DIP8 plastic dual in-line package; 8 leads (300 mil) SOT97-1
TEA1521P DIP8 plastic dual in-line package; 8 leads (300 mil) SOT97-1
TEA1522P DIP8 plastic dual in-line package; 8 leads (300 mil) SOT97-1
TEA1523P DIP8 plastic dual in-line package; 8 leads (300 mil) SOT97-1
TEA1520T SO14 plastic small outline package; 14 leads; body width 3.9 mm SOT108-1
TEA1521T SO14 plastic small outline package; 14 leads; body width 3.9 mm SOT108-1
TEA1522T SO14 plastic small outline package; 14 leads; body width 3.9 mm SOT108-1
Pin numbers without parenthesis refer to DIP8 packages and within parenthesis refer to SO14 packages.
Fig 1. Block diagram
mgt419
PROTECTION
LOGIC
LOGIC
SUPPLY
TEA152x
VALLEY
POWER-UP
RESET
THERMAL
SHUTDOWN
OSCILLATOR
PWM
stop
low freq
100 mV
0.75 V
0.5 V
blank
short circuit winding
overcurrent
10x
2.5 V
F
1.8 U
1 (1)
2 (2, 3, 4,
5, 9, 10)
3 (6)
4 (7)
8 (14)
7 (12, 13)
6 (11)
5 (8)
DRAIN
n.c.
GND
SOURCE
AUX
REG
RC
V
CC
TEA152X All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 04 — 14 September 2010 4 of 20
NXP Semiconductors
TEA152x
SMPS ICs for low-power systems

7. Pinning information

7.1 Pinning

7.2 Pin description

8. Functional description

The TEA152x family 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 TEA152x family 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
Fig 2. Pin configuration DIP8 Fig 3. Pin configuration SO14
TEA152xP
V
CC
DRAIN
GND
n.c.
RC
SOURCE
REG
AUX
001aae137
1
2
3
4
6
5
8
7
TEA152xT
V
CC
DRAIN
GND n.c.
GND n.c.
GND SOURCE
GND GND
RC GND
REG AUX
001aae138
1
2
3
4
5
6
7 8
10
9
12
11
14
13
Table 3. Pin description
Symbol Pin Description
DIP8 SO14
V
CC
1 1 supply voltage
GND 2 2, 3, 4,
5, 9, 10
ground
RC 36frequency setting
REG 4 7 regul ation input
AUX 5 8 input for voltage from the auxiliary winding for timing
(demagnetization)
SOURCE 6 11 source of the internal MOS switch
n.c. 7 12, 13 not connected
DRAIN 8 14 drain of the internal MOS switch; input for the start-up current
and valley sensing
TEA152X All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 04 — 14 September 2010 5 of 20
NXP Semiconductors
TEA152x
SMPS ICs for low-power systems
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 Underoltage lockout

Initially , the IC is self supplying from the rectified main s volt age. The IC st art s switching as
soon as the voltage on pin V
CC
passes the V
CC(startup)
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.
When for some reason the auxiliary supply is not sufficient, the high-voltage supply also
supplies the IC. 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 primar y
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.
To ensure that the capacitor can be charged within the cha rge 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 volt age is eq ual to the extern al reg ulation voltage (2.5 V)
multiplied by the gain of the error amplifier (typically 20 dB which is 10×).

8.4 Valley switching

A new cycle is started when the primary switch is switched on (see Figure 4). After a
certain time (determined by the oscillator voltage RC 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:
(1)
where:
L
p
= primary self-inductance
C
p
= parasitic capacitance on drain node
1
2 π× L
p
C
p
×()×
----------------------------------------------
TEA152X All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 04 — 14 September 2010 6 of 20
NXP Semiconductors
TEA152x
SMPS ICs for low-power systems
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.
Figure 4
shows the drain voltage together with the valley signal, the signal indicating the
secondary stroke and the RC voltage.
The primary stroke starts some time before the actu al valley at low ringing frequencies,
and some time after the actual valley at high ringing frequencies.
Figure 5 shows a typical curve for a reflected output voltage N × V
o
of 80 V. This voltage is
the output voltage V
o
(see
Figure 6) transferred to the primary side of the transformer with
the factor N (determined by the turns ratio of the transformer).
Figure 5 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.
A: Start of new cycle with valley switching
B: Start of new cycle in a classical PWM system
Fig 4. Signals for valley switching
mgt42
3
drain
valley
secondary
ringing
secondary
stroke
primary
stroke
secondary
stroke
RC
oscillator
regulation level
A
B
TEA152X All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 04 — 14 September 2010 7 of 20
NXP Semiconductors
TEA152x
SMPS ICs for low-power systems

8.5 Demagnetization

The system operates in discontinuous conduction mode all the time. As long as the
secondary stroke has not ended, the oscillator will not start a new primary stroke. During
the first t
suppr
seconds, demagnetization recognition is suppressed. This suppressio n may
be necessary in applications where the transformer has a large leakage induct ance and at
low output voltages.

8.6 Minimum and maximum duty factor

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).

8.7 OverCurrent Protection (OCP)

The cycle-by-cycle peak drain current limit circuit uses the external source resistor R
I
to
measure the current. The circuit is activated after the leading edge bla nking time t
leb
. The
protection circuit limits the source voltage to V
source(max)
, and thus limits the primary peak
current.

8.8 Short-circuit winding protection

The short-circuit winding protection circuit is also activated af ter the leading edge bla nking
time. If the source voltage exceeds the short-circuit winding protection voltage V
swp
, the IC
stops switching. Only a power-on reset will restart normal operation. The short-circuit
winding protection also protects in case of a secondary diode short circuit.

8.9 OverTemperature Protection (OTP)

An accurate temperature protection is provided in the device. When the junction
temperature exceeds the thermal shutdown temperature, the IC stops switching. During
thermal protection, the IC current is lowered to the start-up current. The IC continues
normal operation as soon as the overtemperature situation has disapp eared.
Fig 5. Typical phase of drain ringing at switch-on (at N × V
o
=80V)
0 200 400 800
f (kHz)
phase
(deg)
40
20
20
40
0
mgt424
600
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