Philips TEA1533T, TEA1533AT User Manual

INTEGRATED CIRCUITS

DATA SH EET

TEA1533T; TEA1533AT

GreenChip

Product speciﬁcation Supersedes data of 2002 May 31

II SMPS control IC

2002 Aug 23

Philips Semiconductors Product speciﬁcation

GreenChipTMII 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 reductionat low power standby for improved

system efficiency (<3 W)

• Cycle skipping mode at very low loads; Pi <300 mW at no-load operation for a typical adapter application

• On-chip start-up current source.

Protection features

• Safe restart mode for system fault conditions

• Continuous mode protection by means of

demagnetization detection (zero switch-on current)

• Accurateand adjustable overvoltage protection(latched in TEA1533T, safe restart in TEA1533AT)

• Short winding protection

• Undervoltage protection (foldback during overload)

• Overtemperatureprotection (latched inTEA1533T, safe

restart in TEA1533AT)

• Low and adjustable overcurrent protection trip level

• Soft (re)start

• Mains voltage-dependent operation enabling level.

TEA1533T; TEA1533AT

APPLICATIONS

Besides typical application areas, i.e. adapters and chargers, the device can be used in TV and monitor supplies and all applications that demand an efficient and cost-effective solution up to 250 W.

TEA1533T

TEA1533AT

2002 Aug 23 2

MGU499

Fig.1 Basic application diagram.

Philips Semiconductors Product speciﬁcation

GreenChipTMII SMPS control IC

GENERAL DESCRIPTION

The GreenChip Switched Mode Power Supply (SMPS) control ICs operatingdirectly from the rectified universalmains.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 a reduced frequency and with valley detection.

(1) GreenChip is a trademark of Koninklijke Philips

Electronics N.V.

ORDERING INFORMATION

TYPE

NUMBER

TEA1533T SO14 plastic small outline package; 14 leads; body width 3.9 mm SOT108-1 TEA1533AT

(1)

II is the second generation of green

NAME DESCRIPTION VERSION

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 and reliable supplies can easily be designed using the GreenChipII control IC.

PACKAGE

TEA1533T; TEA1533AT

2002 Aug 23 3

This text is here in white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here in

_white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here inThis text is here in

white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader. white to force landscape pages to be ...

2002 Aug 23 4

ok, full pagewidth

BLOCK DIAGRAM

Philips Semiconductors Product speciﬁcation

GreenChip

GND

CTRL

prot(CTRL)

M-level

−1

burst detect

2.5 V

SUPPLY

MANAGEMENT

internal

FREQUENCY

UVLO start

supply

VOLTAGE

CONTROLLED

OSCILLATOR

CONTROL

POWER-ON

RESET

OVER-

TEMPERATURE

PROTECTION

DEMAG SHORT

PROTECTION

UVLO

< 4.5 V

or UVLO

(TEA1533AT)

LOGIC

UP/DOWN

COUNTER

LOGIC

START-UP

CURRENT SOURCE

OCP

VALLEY

100

VOLTAGE

PROTECTION

LEB

blank

OCP

OVER-

DRIVER

prot(DEM)

clamp

start

soft

DRAIN

12, 13

0.5 V

HVS n.c.

DEM

DRIVER

sense

II SMPS control IC

TEA1533T; TEA1533AT

TEA1533T

TEA1533AT

MAXIMUM

ON-TIME

PROTECTION

Fig.2 Block diagram.

short

winding

0.88 V

OVERPOWER PROTECTION

MGU500

Philips Semiconductors Product speciﬁcation

GreenChipTMII SMPS control IC

TEA1533T; TEA1533AT

PINNING FUNCTIONAL DESCRIPTION

SYMBOL PIN DESCRIPTION

n.c. 1 not connected V

2 supply voltage

GND 3 ground

The TEA1533 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 TEA1533 can operate in multi modes (see Fig.4).

n.c. 4 not connected n.c. 5 not connected CTRL 6 control input DEM 7 input from auxiliary winding for

demagnetization timing, overvoltage and overpower protection

handbook, halfpage

(kHz)

VCO fixed quasi resonant

175

n.c. 8 not connected I

sense

9 programmable current sense input n.c. 10 not connected DRIVER 11 gate driver output

HVS 12 high voltage safety spacer, not

connected

HVS 13 high voltage safety spacer, not

connected

Fig.4 Multi modes operation.

DRAIN 14 drain of external MOS switch, input for

start-up current and valley sensing

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 draincapacitorensuresthis quasi-resonant operation. The design can be optimized in such a way that zero voltage

handbook, halfpage

n.c.

GND

n.c. n.c.

CTRL

DEM

1 2 3 4

TEA1533AT

5 6 7

TEA1533T

MGU501

14 13 12 11 10

9 8

DRAIN HVS HVS DRIVER n.c. I

sense

n.c.

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, mains enabling operation level and undervoltage lock-out

MGU508

P (W)

Fig.3 Pin configuration.

2002 Aug 23 5

Initially, the IC is self supplying from the rectified mains voltage via pin DRAIN (see Figs 11 and 12). Supply capacitor C

is charged by the internal start-up current

VCC

source to approximately 4 V or higher, depending on the voltage on pin DRAIN.

Philips Semiconductors Product speciﬁcation

GreenChipTMII SMPS control IC

Once the drain voltage exceeds the M-level (mains-dependent operation-enabling level), the start-up current source will continue charging capacitor C (switch S1 will be opened); see Fig.2. The IC will activate the converter as soon as the voltage on pin VCC passes the V

level. The IC supply is taken over by the

CC(start)

auxiliary winding assoon 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 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.

VCC

handbook, halfpage

sense(max)

Fig.5 V

handbook, halfpage

(kHz)

0.52 V

sense(max)

175

TEA1533T; TEA1533AT

MGU233

MGU509

175 kHz

CTRL

1 V

(typ)

1.5 V (typ)

voltage as function of V

Current mode control

Current mode control is used for its good line regulation behaviour.

The ‘on-time’ iscontrolled by theinternally 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 inverselyproportional 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 isset 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 changeslinearly with thecontrol voltage untilthe minimum frequency is reached (see Figs 5 and 6).

level

VCO

level

sense(max) (V)

sense(max)

VCO

Fig.6 VCO frequency as function of V

Cycle skipping

At very low power levels, a cycle skipping mode will be activated. A high control voltage will reduce the switching frequency to a minimum of 25 kHz. If the voltage on the control pin is raised even more, switch-on of the external power MOSFET will be inhibited until the voltage on the control pin has dropped to a lower value again (see Fig.7).

For system accuracy it is not the absolute voltage on the control pin that will trigger the cycle skipping mode, but a signal derived from the internal VCO will be used.

Remark 1:If the no-loadrequirementof the systemissuch that the output voltage can be regulated to its intended level at a switching frequency of 25 kHz or above, the cycle skipping mode will not be activated.

2002 Aug 23 6

Remark 2: As switching will stop when the voltage on the control pin is raised above a certain level, the burst mode has to beactivated by amicrocontroller or any other circuit sending a 30 µs, 16 mA pulse to the control input (pin CTRL) of the IC.

Philips Semiconductors Product speciﬁcation

GreenChipTMII SMPS control IC

handbook, full pagewidth

CTRL

1.5 V − V

CTRL

150 mV

current

comparator

DRIVER

OSCILLATOR

DRIVER

sense

TEA1533T; TEA1533AT

osc

max

min

cycle

skipping

150

Vx (mV)

MGU510

Vx (mV)

The voltage levels dV1 and dV2 are fixed in the IC to 50 mV (typical) and 18 mV (typical) respectively.

Fig.7 The cycle skipping circuitry.

Demagnetization

The system will be in discontinuous conduction mode all the time. The oscillator will not start a new primary stroke until the secondary stroke has ended.

Demagnetization features a cycle-by-cycle output short-circuit protection by immediately lowering the frequency (longer off-time), thereby reducing the power

Minimum and maximum ‘on-time’

The minimum ‘on-time’ of the SMPS is determined by the Leading Edge Blanking (LEB) time. The IC limits the ‘on-time’ to 50 µs. When the system desires an ‘on-time’ longer than 50 µs, a fault condition is assumed (e.g. removed Ciin Fig.11), the IC will stop switching and enter

the safe restart mode. level. Demagnetizationrecognition is suppressedduringthe first

time. This suppression may be necessary in

suppr

applications where the transformer has a large leakage inductance, at low output voltages and at start-up.

If pin DEM is open-circuit or not connected, a fault condition is assumed and the converter will stop operating immediately. Operation will recommence as soon as the fault condition is removed.

If pin DEM is shorted to ground, again a fault condition is assumed and the converter will stop operating after the first stroke. The converter will subsequently enter the safe restart mode. This situation will persist until the short-circuit is removed.

2002 Aug 23 7

Philips Semiconductors Product speciﬁcation

GreenChipTMII SMPS control IC

OverVoltage Protection (OVP)

An OVP mode is implemented in the GreenChip series. This works for the TEA1533 by sensing the auxiliary voltage via the current flowing into pin DEM during the secondary stroke. The auxiliary winding voltage is a well-defined replica of the output voltage. Any voltage spikes are averaged by an internal filter.

Ifthe output voltage exceedstheOVP trip level, aninternal counter starts counting subsequent OVP events. The counter has been added to prevent incorrect OVP detections which might occur during ESD or lightning events. If the output voltage exceeds the OVP trip level a fewtimes and notagain in asubsequent cycle, theinternal counter will count down with twice the speed compared with counting up. However, when typical 10 cycles of subsequent OVP events are detected, the IC assumes a true OVP and the OVP circuit switches the power MOSFET off. Next, the controller waits until the UVLO level is reached on pin VCC. When VCC drops to UVLO, capacitor C

Regarding the TEA1533T, this IC will not start switching again. Subsequently, VCC will drop again to the UVLO level, etc. Operation only recommences when the V voltage drops below a level of approximately 4.5 V (practically when V period).

will be recharged to the V

VCC

has been disconnectedfor a short

mains

start

level.

TEA1533T; TEA1533AT

Valley switching

A new cycle starts when the power MOSFET is switched

on (see Fig.8). After the ‘on-time’ (which is determined by

the ‘sense’ voltage and the internal control voltage), the

switchis opened andthesecondary stroke starts.Afterthe

secondary stroke, the drain voltage shows an oscillation

with a frequency of approximately

----------------------------------------------2π×L

where L

is the primary self inductance of the transformer

and Cd is the capacitance on the drain node.

As soon as the oscillator voltage is high again and the

secondary stroke has ended, the circuit waits for the

lowest drain voltage before starting a new primary stroke.

This method is called valley detection. Figure 8 shows the

drain voltage together with the valley signal, the signal

indicating the secondary stroke and the oscillator signal.

In an optimum design, the reflected secondary voltage on

the primary side will force the drain voltage to zero. Thus,

zero voltage switching is very possible, preventing large



capacitive switching losses and

-- -



allowing high frequency operation, which results in small

and cost effective inductors.

×()×

× f××=

Regarding the TEA1533AT, switching starts again (safe restart mode) when the V

level is reached. This

start

process is repeated as long as the OVP condition exists. Theoutput voltage V

can be set by the demagnetization resistor, R

----------N

o OVP()

(OVP)(DEM)RDEM

aux

× V

where Nsis the number of secondary turnsand N

atwhich the OVPfunctiontrips,

o(OVP)

DEM

+{}

clamp(DEM)(pos)

is the

aux

number of auxiliary turns of the transformer. Current I

(OVP)(DEM)

The value of R

is internally trimmed.

can be adjusted to the turns ratio of the

DEM

transformer, thus making an accurate OVP possible.

2002 Aug 23 8

+ 16 hidden pages

Philips TEA1533T, TEA1533AT User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

APPLICATIONS

GENERAL DESCRIPTION

ORDERING INFORMATION

BLOCK DIAGRAM

PINNING FUNCTIONAL DESCRIPTION