ST ALTAIR05T-800 User Manual

Off-line all-primary-sensing switching regulator

Features

■ Constant voltage and constant current output

regulation (CV/CC) with no optocoupler

■ Tight regulation also in presence of heavy load

transients

■ 800 V avalanche rugged internal power section

■ Quasi-resonant (QR) operation

■ Low standby power consumption

■ Automatic self-supply

■ Input voltage feedforward for mains-

independent cc regulation

■ Output cable drop compensation

■ SO16 package

ALTAIR05T-800

SO16N

Applications

■ AC-DC chargers for mobile phones and other

hand-held equipments

■ Compact SMPS that requires a precise current

and/or voltage regulation

Description

Figure 1. Block diagram

Vcc

Vcc

PROTECTION &

PROTECTION &

PROTECTION &

FEE DFO R WAR D

FEE DFO R WAR D

FEE DFO R WAR D

CDC

CDC

Rcdc

Rcdc

Rzcd

Rzcd

ZCD/F B

ZCD/F B

Rfb

Rfb

S/H

S/HS/H

2.5 V

2.5 V

LOGI C

LOGI C

LOGI C

Prot I

Prot I

ESTIMATE

ESTIMATE

DEMAG

DEMAG

DEMAG

LOGIC

LOGIC

LOGIC

-

-

+

+

COMP

COMP

VcIout

VcIout

FF

FF

Rcomp

Rcomp

Ccomp

Ccomp

ALTAIR05T-800 is a high-voltage all-primary
sensing switcher intended for operating directly
from the rectified mains with minimum external
parts. It combines a high-performance low­voltage PWM controller chip and an 800 V
avalanche-rugged power section in the same
package.

+Vout

+Vin

+Vin

Ista rt-u p

Ista rt-u p

Internal s upply bus

Internal s upply bus

BLANKING

BLANKING

BLANKING

TIME

TIME

IREF

IREF

TIME

Vc

Vc

-

-+-

+

+

Iref

Iref

+

+-+

-

-

Cref

Cref

3.3 V

3.3 V

R

R

S

S

S

Q

Q

Q

R

R

R

Vref

Vref

TURN -O N

TURN -O N

LOGIC

LOGIC

GND

GND

I

I

FF

FF

RFF

RFF

SUPPL Y

SUPPL Y
& UVLO

& UVLO

STARTER

STARTERSTARTER

LEB

LEBLEB

1 V

1 V

UVLO

UVLO

Int er n .

Int er n .
supply

supply

bus

S

S

Q

Q

R

R

-

-+-

+

+

bus

S

S

S

UVLO

UVLO

Q

Q

Q

R

R

R

Prot

Prot

SOURCE

SOURCE

Rsense

Rsense

DRAIN

DRAIN

+Vout

October 2010 Doc ID 17957 Rev 1 1/28

www.st.com

28

Contents ALTAIR05T-800

Contents

1 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.1 Power section and gate driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5.2 High-voltage start-up generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5.3 Zero current detection and triggering block . . . . . . . . . . . . . . . . . . . . . . . 13

5.4 Constant voltage operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5.5 Constant current operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5.6 Voltage feedforward block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.7 Cable drop compensation (CDC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.8 Burst-mode operation at no load or very light load . . . . . . . . . . . . . . . . . . 20

5.9 Soft-start and starter block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.10 Hiccup mode OCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.11 Layout recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

8 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2/28 Doc ID 17957 Rev 1

ALTAIR05T-800 Device description

1 Device description

The device combines two silicon in the same package: a low voltage PWM controller and
an 800 V avalanche rugged power section.

The controller chip is a current-mode specifically designed for offline quasi-resonant flyback
converters.

The device features a unique characteristic: it is capable of providing constant output
voltage (CV) and constant output current (CC) regulation using primary-sensing feedback.
This eliminates the need for the optocoupler, the secondary voltage reference, as well as the
current sensor, still maintaining quite accurate regulation also in presence of heavy load
transients. Additionally, it is possible to compensate the voltage drop on the output cable, so
as to improve CV regulation on the external accessible terminals.

Quasi-resonant operation is guaranted by means of a transformer demagnetization sensing
input that turns on the power section. The same input serves also the output voltage
monitor, to perform CV regulation, and the input voltage monitor, to achieve mains­independent CC regulation (line voltage feedforward).

The maximum switching frequency is top-limited below 166 kHz, so that at medium-light
load a special function automatically lowers the operating frequency still maintaining the
valley switching operation. At very light load, the device enters a controlled burst-mode
operation that, along with the built-in high-voltage start-up circuit and the low operating
current, helps minimize the standby power.

Although an auxiliary winding is required in the transformer to correctly perform CV/CC
regulation, the chip is able to power itself directly from the rectified mains. This is useful
especially during CC regulation, where the flyback voltage generated by the winding drops
below UVLO threshold. However, if ultra-low no-load input consumption is required to
comply with the most stringent energy-saving recommendations, then the device needs to
be powered via the auxiliary winding.

In addition to these functions that optimize power handling under different operating
conditions, the device offers protection features that considerably increase end-product’s
safety and reliability: auxiliary winding disconnection - or brownout – detection and shorted
secondary rectifier - or transformer’s saturation – detection. All of them are auto restart
mode.

Doc ID 17957 Rev 1 3/28

Pin connection ALTAIR05T-800

2 Pin connection

Figure 2. Pin connection (top view)

SOURCE

SOURCE

SOURCE

SOURCE

Vcc

Vcc

GND

GND

IREF

IREF

ZCD/FB

ZCD/FB

COM P

COM P

CDC

CDC

1

1

1

2

2

2

3

3

3

4

4

4

5

5

5

6

6

6

7

7

7

8

8

8

16

16

16

15

15

15

14

14

14

13

13

13

12

12

12

11

11

11

10

10

10

DRAIN

DRAIN

DRAIN

DRAIN

DRAIN

DRAIN

DRAIN

DRAIN

DRAIN

DRAIN

N.C.

N.C.

N.A.

N.A.

N.A.

N.A.

9

9

9

N.A.

N.A.

Note: The copper area for heat dissipation has to be designed under the drain pins

Table 1. Pin functions

N. Name Function

Power section source and input to the PWM comparator. The current flowing in the MOSFET
is sensed through a resistor connected between the pin and GND. The resulting voltage is

1, 2 SOURCE

3Vcc

compared with an internal reference (0.75V max.) to determine MOSFET’s turn-off. The pin
is equipped with 250 ns blanking time after the gate-drive output goes high for improved
noise immunity. If a second comparison level located at 1V is exceeded the IC is stopped and
restarted after Vcc has dropped below 5V.

Supply Voltage of the device. An electrolytic capacitor, connected between this pin and
ground, is initially charged by the internal high-voltage start-up generator; when the device is
running the same generator keeps it charged in case the voltage supplied by the auxiliary
winding is not sufficient. This feature is disabled in case a protection is tripped. Sometimes a
small bypass capacitor (0.1 µF typ.) to GND might be useful to get a clean bias voltage for
the signal part of the IC.

Ground. Current return for both the signal part of the IC and the gate drive. All of the ground

4GND

connections of the bias components should be tied to a trace going to this pin and kept
separate from any pulsed current return.

CC regulation loop reference voltage. An external capacitor has to be connected between

5IREF

this pin and GND. An internal circuit develops a voltage on this capacitor that is used as the
reference for the MOSFET’s peak drain current during CC regulation. The voltage is
automatically adjusted to keep the average output current constant.

4/28 Doc ID 17957 Rev 1

ALTAIR05T-800 Pin connection

Table 1. Pin functions (continued)

N. Name Function

Transformer’s demagnetization sensing for quasi-resonant operation. Input/output voltage
monitor. A negative-going edge triggers MOSFET’s turn-on. The current sourced by the pin
during ON-time is monitored to get an image of the input voltage to the converter, in order to
compensate the internal delay of the current sensing circuit and achieve a CC regulation
independent of the mains voltage. If this current does not exceed 50µA, either a floating pin

6 ZCD/FB

7COMP

8CDC

or an abnormally low input voltage is assumed, the device is stopped and restarted after Vcc
has dropped below 5V. Still, the pin voltage is sampled-and-held right at the end of
transformer’s demagnetization to get an accurate image of the output voltage to be fed to the
inverting input of the internal, transconductance-type, error amplifier, whose non-inverting
input is referenced to 2.5V. Please note that the maximum I
to not exceed ±2 mA (AMR) in all the Vin range conditions (85-265 Vac). No capacitor is
allowed between the pin and the auxiliary transformer.

Output of the internal transconductance error amplifier. The compensation network is placed
between this pin and GND to achieve stability and good dynamic performance of the voltage
control loop.

Cable drop compensation input. During CV regulation this pin, capable of sinking current,
provides a voltage lower than the internal reference voltage (2.5V) by an amount proportional
to the dc load current. By connecting a resistor between this pin and ZCD/FB, the CV
regulation setpoint is increased proportionally. This allows that the voltage drop across the
output cable be compensated and, ideally, that zero load regulation at the externally available
terminals be achieved. Leave the pin open if the function is not used.

sunk/sourced current has

ZCD/FB

9-11 N.A Not available. These pins must be left not connected

12 N.C Not internally connected. Provision for clearance on the PCB to meet safety requirements.

Drain connection of the internal power section. The internal high-voltage start-up generator

13 to 16 DRAIN

sinks current from this pin as well. Pins connected to the internal metal frame to facilitate
heat dissipation.

Doc ID 17957 Rev 1 5/28

Maximum ratings ALTAIR05T-800

3 Maximum ratings

3.1 Absolute maximum ratings

Table 2. Absolute maximum ratings

Symbol Pin Parameter Value Unit

V

Eav 1,2, 13-16 Single pulse avalanche energy (Tj = 25°C, I

Vcc 3 Supply voltage (Icc < 25mA) Self limiting V

I

ZCD/FB

I

1,2, 13-16 Drain-to-source (ground) voltage -1 to 800 V

DS

1,2, 13-16 Drain current 1 A

I

D

6 Zero current detector current ±2 mA

--- 7, 8 Analog inputs and outputs -0.3 to 3.6 V

CDC

8 Maximum sunk current 200 µA

Ptot Power dissipation @T

Tj Junction temperature range -25 to 150 °C

Tstg Storage temperature -55 to 150 °C

3.2 Thermal data

Table 3. Thermal data

Symbol Parameter Max. value Unit

R

th j-pin

R

th j-amb

Thermal resistance, junction-to-pin 10

Thermal resistance, junction-to-ambient 110

= 1A) 50 mJ

D

= 50°C 0.9 W

A

°C/W

6/28 Doc ID 17957 Rev 1

ALTAIR05T-800 Electrical characteristics

4 Electrical characteristics

(TJ = -25 to 125 °C, Vcc = 14 V; unless otherwise specified)

Table 4. Electrical characteristics

Symbol Parameter Test condition Min. Typ. Max. Unit

Power section

V

(BR)DSS

I

DSS

Drain-source breakdown ID< 100 µA; Tj = 25 °C 800 V

V

= 750 V; Tj = 125 °C

Off state drain current

DS

(See Figure 4 and note)

80 µA

Id=100 mA; Tj = 25 °C 11 14

R

DS(on)

C

Drain-source ON-state resistance

Effective (energy-related) output capacitance (See Figure 3)

oss

Id=100 mA; Tj = 125 °C 22 28

High-voltage start-up generator

V

Start

I

charge

V

CCrestart

Min. Drain start voltage I

Vcc startup charge current

Vcc restart voltage (Vcc falling)

< 100 µA 40 50 60 V

charge

V

> V

DRAIN

Tj = 25 °C

(1)

Start

; VCC<V

CCOn

45.57mA

9.5 10.5 11.5

After protection tripping 5

Supply voltage

Vcc Operating range After turn-on 11.5 23 V

Vcc

Vcc

Turn-on threshold

On

Turn-off threshold

Off

V

Zener voltage Icc = 20 mA 23 25 27 V

Z

(1)

(1)

12 13 14 V

91011V

Supply current

Ω

V

Icc

start-up

Start-up current (See Figure 5) 200 300 µA

Iq Quiescent current (See Figure 6)11.4mA

Icc Operating supply current @ 50 kHz (See Figure 7)1.41.7mA

Iq

(fault)

Fault quiescent current

During hiccup and brownout
(See Figure 8)

250 350 µA

Start-up timer

T

START

T

RESTART

Start timer period 100 125 175 µs

Restart timer period during burst mode 400 500 700 µs

Zero current detector

I

ZCDb

V

ZCDH

Input bias current V

Upper clamp voltage I

= 0.1 to 3 V 0.1 1 µA

ZCD

= 1 mA 3.0 3.3 3.6 V

ZCD

Doc ID 17957 Rev 1 7/28

Electrical characteristics ALTAIR05T-800

Table 4. Electrical characteristics (continued)

Symbol Parameter Test condition Min. Typ. Max. Unit

V

ZCDL

V

ZCDA

V

ZCDT

I

ZCDON

T

BLANK

Lower clamp voltage I

= - 1 mA -90 -60 -30 mV

ZCD

Arming voltage positive-going edge 100 110 120 mV

Triggering voltage negative-going edge 50 60 70 mV

Min. source current during MOSFET ON-time -25 -50 -75 µA

V

≥ 1.3V 6

Trigger blanking time after MOSFET’s turn-off

COMP

= 0.9V 30

V

COMP

Line feedforward

R

Equivalent feedforward resistor

FF

I

= 1mA 45 Ω

ZCD

Transconductance error amplifier

V

REF

Voltage reference

gm Transconductance

Tj = 25°C

Tj = -25 to 125°C and
Vcc=12V to 23V

∆I

COMP

V

COMP

(1)

(1)

= ±10 µA

= 1.65 V

2.46 2.5 2.54

2.42 2.58

1.3 2.2 3.2 mS

Gv Voltage gain Open loop 73 dB

GB Gain-bandwidth product 500 KHz

I

COMP

V

COMPH

V

COMPL

V

COMPBM

Source current V

Sink current V

Upper COMP voltage V

Lower COMP voltage V

Burst-mode threshold 1 V

= 2.3V, V

ZCD

= 2.7V, V

ZCD

= 2.3 V 2.7 V

ZCD

= 2.7 V 0.7 V

ZCD

= 1.65V 70 100 µA

COMP

= 1.65V 400 750 µA

COMP

Hys Burst-mode hysteresis 65 mV

µs

V

CDC function

V

CDC

CDC voltage reference V

COMP

= 1.1V, I

Current reference

V

IREFx

V

CREF

Maximum value

Current reference voltage 0.192 0.2 0.208 V

V

COMP

Current sense

t

LEB

t

d(H-L)

V

V

CSdis

1. Parameters tracking each other

Leading-edge blanking 200 250 300 ns

Delay-to-output 300 ns

Max. clamp value

CSx

Hiccup-mode OCP level

dVcs/dt = 200 mV/µs

(1)

8/28 Doc ID 17957 Rev 1

= V

CDC

COMPL

= 1µA

(1)

(1)

(1)

2.4 2.5 2.6 V

1.5 1.6 1.7 V

0.70.750.8 V

0.9211.08V

ALTAIR05T-800 Electrical characteristics

Figure 3. C

output capacitance variation

OSS

C

(pF)

OSS

500

400

300

200

100

0

0 25 50 75 100 125 150

V

(V)

DS

Figure 4. Off state drain and source current test circuit

14 V

CDC

2. 5V

FB/ZCD

+

-

COMP SOURCE

IR E F

CURRENT
CONTROL

DRAINVDD

GND

Ids s

A

Vin
75 0V

Note: The measured I

effective MOSFET’s off state drain current.

Figure 5. Start-up current test circuit

is the sum between the current across the start-up resistor and the

DSS

CDC

2. 5V

FB/ZCD

Iccst art-up

+

-

COMP SOURCE

A

IR EF

Doc ID 17957 Rev 1 9/28

1 1.8 V

CURRENT
CONTROL

GND

DRAINVDD