Panasonic AN8037, AN8027 Datasheet

Voltage Regulators

AN8027, AN8037

AC-DC switching power supply control IC with standby mode

■ Overview

The AN8027 and AN8037 are ICs developed for self-

6.0±0.3

2.4±0.25

3.3±0.25

Unit: mm

excited switching regulator of RCC local resonance control type.

These ICs are designed to achieve stability and high efficiency over a wide input voltage range and loads range (light loads to heavy loads), for supporting input levels used worldwide and improved conformance with energy conservation laws.

■ Features

• Support improved conformance with energy conserva-

tion laws by providing two operating modes.

• Standby mode (light loads): Achieves better efficiency due to reduced frequency .

• Normal mode:

23.3±0.3

9 8 7 6 5 4 3 2

SIP009-P-0000C

0.3

+0.1 –0.05

0.5±0.1

2.54

1.5±0.25

3.0±0.3

30°

1.4±0.3

Achieves high efficiency in RCC local resonance operation with zero-cross detection.

• Incorporating an input voltage compensation function available to a wide input range for worldwide use.

• This function compensates the maximum on-period in inverse proportion to the input voltage.

• Incorporating a timer latch function.

• The time period can be adjusted according to the overload in normal mode or standby mode.

• This function makes it possible to protect the IC from damage that may be caused by the short-circuiting of the IC's external capacitor for the timer.

• Incorporating an overvoltage protection function. (detects at V

pin)

• Incorporating a pulse-by-pulse overcurrent protection function, which makes latch protection possible at the time of

the short-circuiting of the transformer's primary winding.

• Adopting a 9-pin single inline package (E-9S: available to manufacturing in overseas).

• AN8027: Transformer resetting is detected from the high- or low-level signal on the TR pin.

• AN8037: Transformer resetting is detected from the falling edge of the high-level signal on the TR pin.

Refer to the "[1] operation descriptions 7. local resonance operation" section in the application notes.

■ Applications

• Televisions, VCRs, facsimiles, and printers

AN8027, AN8037 Voltage Regulators

■ Block Diagram

INIT

Current

reviser (IFB)

High-side

clamp

Start

Stop

REF

Q Q

7.1 V

Q Q

Out

Drive

Out

GND

OCP

OVP

Timer

3.8 V

0.5 V

(SD latch)

RS Q

CF latch

OFF

To timer

− 0.2 V

CLM

High-side

Low-side

(− 0.15 V)

I/V

conv.

(0.7 V)

clamp

reviser (I

0.35 V

Current

One shot

Start

pulse

1.0 V

)

■ Absolute Maximum Ratings

Parameter Symbol Rating Unit

Supply voltage V Constant output current I Peak output current I TR pin allowable application current I OCP pin allowable application voltage V CLM pin allowable application voltage V SD pin allowable application voltage V FB pin allowable application current I Power dissipation (Ta ≤ 25°C) P

OUT

OCP

CLM

Power dissipation (Ta = 85°C) 454 mW Operating ambient temperature Storage temperature

Note) 1. *: Except for the operating ambient temperature and storage temperature, all ratings are for Ta = 25°C.

2. Do not apply external currents or voltages to any pins not specifically mentioned.

For circuit current, '+' denotes current flowing into the IC, and '−' denotes current flowing out of the IC.

opr

stg

24 V

±150 mA

±1 000 mA

±5mA

− 0.3 to +7.0 V

0 to −2.0 mA

874 mW

−30 to +85 °C

−55 to +150 °C

■ Recommended Operating Range

Parameter Symbol Range Unit

Supply voltage V

From the stop voltage to the OVP supply voltage V

Voltage Regulators AN8027, AN8037

■ Electrical Characteristics at VCC = 18 V, Ta = 25°C

Parameter Symbol Conditions Min Typ Max Unit

Low voltage protection (U.V.L.O.) V initial startup supply voltage

Low voltage protection (U.V.L.O.) V operation stop supply voltage

Overvoltage protection (OVP) V operating supply voltage

Overvoltage protection (SD) V operating threshold voltage

Overvoltage protection (SD) V reset threshold voltage

Remote (RM) operating V threshold voltage

Shutdown (SD) standby voltage V Overvoltage protection (OVP) V

reset supply voltage Remote (RM) operating time I

circuit current Overvoltage protection (SD) I

operating time circuit current 1 Overvoltage protection (SD) I

operating time circuit current 2 Timer latch (SD) charge current 1 I Timer latch (SD) charge current 2 I Timer latch (SD) start feedback I

current Transformer reset detection (TR) V

threshold voltage Transformer reset detection (TR) V

upper limit clamp voltage Transformer reset detection (TR) V

lower limit clamp voltage Overcurrent protection (CLM) V

threshold voltage Oscillator (CF) upper limit voltage Oscillator (CF) lower limit voltage 1 Oscillator (CF) lower limit voltage 2 Oscillator (CF) maximum G

on-period current gain Oscillator (CF) maximum I

on-period current Oscillator (CF) minmum I

off-period current 1

CC-START

CC-STOP

CC-OVP

TH1-SD

TH2-SD

TH1-RM

STB-SD

CC-OVPC

CC-RMVCC

CC1-SDVCC

CC2-SDVCC

SD1-TIM

SD2-TIM

FB-TIMITR

TH-TR

CLH-TRITR

CLL-TRITR

TH-CLM

V V V

ION-CF

ON-CFITR

OFF1-CFIFB

SD pin = Open 1.0 1.5 2.0 V

FB pin = Open, ITR = −270 µA 68 102 136 µA FB pin = Open, ITR = −1.64 mA 179 267 355 µA

FB pin = Open, CF = 2 200 pF 3.8 4.2 4.6 V

H-CF

FB pin = Open, CF = 2 200 pF 0.8 1.0 1.2 V

L1-CF

L2-CFIFB

FB pin = Open, ITR = −750 µA 0.8 1.0 1.2 

= 18 V, VSD = 0 V 3.0 4.0 5.0 mA

= 10 V, VSD = 4.3 V → Open 1.2 1.5 1.8 mA

= 18 V, VSD = 4.3 V → Open 3.6 4.5 5.4 mA

= −1 mA, R

= 30 kΩ− 0.95 − 0.75 − 0.55 mA

OCP

= 3 mA 0.55 0.7 0.85 V

= −3 mA − 0.3 − 0.15 0 V

= − 0.5 mA, CF = 2 200 pF 0 0.1 0.3 V

= 0 mA 200 250 300 µA

= − 0.4 mA −880 −660 −440 µA

13.4 14.9 16.4 V

7.7 8.6 9.5 V

19.4 20.5 21.6 V

3.5 3.9 4.3 V

0.4 0.8 1.2 V

0.05 0.15 0.3 V

7.3 8.1 8.9 V

0.15 0.25 0.35 V

−220 −200 −180 mV

AN8027, AN8037 Voltage Regulators

■ Electrical Characteristics at VCC = 18 V, Ta = 25°C (continued)

Parameter Symbol Conditions Min Typ Max Unit

Oscillator (CF) minmum I

OFF2-CFIFB

off-period current 2 Minimun off-period threshold I

FB-TOFF

feedback current Overcurrent protection (OCP) pin I

OCP-OCP

source current Output oscillator frequency F

Pre-startup low-level output voltage V Low-level output voltage V High-lebel output voltage V Pre-startup circuit current 1 I Circuit current 1 I Circuit current 2 I Circuit current durring startup 1 I

CC-STB1VCC

CC1-OPR1VCC

CC2-OPR2VCC

START1

OSC

OL-STBVCC

OLIOUT

OHIOUT

= − 0.8 mA −210 −160 −110 µA

− 0.78 − 0.6 − 0.42 mA

−130 −100 −70 µA

CF = 2 200 pF, ITR = 475 µA, 50 65 80 kHz IFB = − 0.5 mA

= 13.5 V, I

= 1 mA  1.0 1.25 V

OUT

= 0.1 A  0.9 2.0 V

= − 0.1 A 15.5 16.3  V = 13.5 V 75 100 125 µA = 10 V 8.5 11.5 14.5 mA = 18 V 9.0 12.0 15.0 mA

 200 380 µA

• Design reference data

Note) The characteristics listed below are theoretical values based on the IC design and are not guaranteed.

Parameter Symbol Conditions Min Typ Max Unit

Low voltage protection (U.V.L.O.) ∆V

 6.3  V

start/stop supply voltage difference Remote (RM) reset threshold voltage V Timer latch (SD) overcurrent T

TH2-RM

CLM-SD

 0.1  V  0.1  s

protection time Transformer reset detection (TR) ∆V

TH-TR

 0.05  V

threshold hysteresis width Maximum on-period T Minimum off-period T Overcurrent protection (OCP) T

ON(max)ITR

OFF(min)ITR

SD(ON)-OCPIFB

= 0 mA, IFB = − 0.2 mA  26.5 µs = 0 mA, IFB = − 0.2 mA  5 µs = − 0.5 mA, R

= 22 kΩ1.8 µs

OCP

power-on charge period Overcurrent protection (OCP) T

SD(OFF)-OCPIFB

= − 0.5 mA, R

= 30 kΩ8.8 µs

OCP

power-off charge period Output rise time t Output fall time t TR output response time T CLM output response time T Pre-startup circuit current 2 I

CC-STB2

CLM

10% to 90%, I 10% to 90%, I

= 0 mA  60  ns

OUT

= 0 mA  20  ns

OUT

 800  ns  100  ns

VCC = 13.5 V, 50 1 0 0 150 µA Ta = −30°C to +85°C

Only for AN8037

Timer period during startup T

START

 100 µs

Voltage Regulators AN8027, AN8037

REF

OFF

Comp.

■ Pin Descriptions

Pin No. Pin name I/O Explanation Equivalent Circuit

1 TR I Transformer reset detection input. When the

IC detects transformer resetting and the falling edge of a high-level signal is input to this pin of the AN8037 or a low-level signal is input to the same pin of the AN8027, the level of the Out pin becomes high. However, the transformer reset signal is ignored if the signal is shorter than the minimum off-period determined by the CF pin. Also note that the maximum on-period is corrected according to the source currents.

2 OCP  Connection for the resistor that determines

the overload level of the IC to activate the timer latch protection circuit. By judging the operating mode (i.e., the normal or standby mode) of the IC from the secondary side, the timer period is adjusted with the selection of external resistance according to the operating mode.

3CF Connection for the capacitor that determines

the on- and off-periods of the IC output (Out). The on- and off-periods are corrected by I which is proportional to the flowing out current at the TR pin, and I

which corre-

OFF

sponds to the current at FB pin.

REF

High-side

clamp

Comp.

Low-side

clamp

4 CLM I Input to the pulse-by-pulse overcurrent pro-

tection circuit. Normally, we recommend adding an external filter for this input. If overcurrent continues

REF

Comp.

for several cycles, the IC determines that the operation is erroneous, thus triggering the latch protection function.

CLM(−)

5 GND  IC ground.

AN8027, AN8037 Voltage Regulators

■ Pin Descriptions (continued)

Pin No. Pin name I/O Explanation Equivalent Circuit

6 Out O Output used to directly drive a power MOSFET.

A totem pole structure is adopted in this output circuit. The absolute maximum ratings for the output current are:

Peak: ±1 A DC: ±150 mA

7VCC Power supply.

This pin monitors supply voltage and has the threshold for the start, stop, OVP, and OVP reset levels.

8 SD I This pin is used in RM (remote), OVP (over-

voltage protection), and timer latch. RM: The IC is in remote operation if this pin is short-circuited to the ground and the output of the IC is turned off. OVP: When overvoltage signal of the power supply is detected and high is inputted to the terminal, it turns off the internal circuit. At the same time, it holds that condition (latch). Timer latch: It detects the output voltage fall due to the overcurrent condition of the power supply output through the current level inputted to FB. When the I

decreases under the current

of certain value, the charge current flows in the capacitor which is connected to this terminal. Then, when the capacitor is charged up to the threshold voltage of the OVP, the OVP works so that the IC could keep the operation stop condition.

9 FB I Connection for the photocoupler used for the

power supply output error-voltage feedback. This input can decrease the photocoupler dark current by about 200 µA.

OVP

Comp.

REF

3.9 V

0.1 V

25 µA

TIM

Voltage Regulators AN8027, AN8037

■ Application Notes

[1] Operation descriptions

1. Start/stop circuit block

• Startup mechanism

After the AC voltage is applied and the supply voltage due to the current in the startup resistor reaches the startup voltage and the IC begins to operate, drive of the power MOSFET begins. This causes a bias in the transformer, and the supply voltage is provided to the IC from the bias winding. (This is point a in figure 1.) During the period between the point when the startup voltage is reached, and the point when the bias winding can generate a voltage enough to supply the IC, the IC supply voltage is provided by the capacitor (C8) connected to V Since the supply voltage falls during this period (area b in figure 1), if the supply voltage falls below the IC stop-voltage before an adequate supply voltage can be provided by the bias winding, it will not be possible to start the power sup-

Startup voltage

Stop voltage

ply. (This is the state at point c in figure 1.)

• Functions

This IC includes a function that monitors the V

voltage (14.9 V typical), and stops operation when the voltage falls below the stop voltage (8.6 V typical). Since a large voltage difference (6.3 V typical) is taken between the start and stop voltages, it is easy to select values for the start resistor and the capacitor connected to V

Note) To start up the IC operation, the startup current which is a pre-start current plus a circuit drive current is necessary.

Set the resistance value so as to supply a startup current of 400 µA.

Rectified AC

Startup resistor

OUT

GND

StartupStandby

Voltage supplied

from bias winding

Startup state

Startup failure

Figure 1

voltage. It starts IC operation when VCC reaches the startup

2. Oscillation circuit

The oscillation circuit makes use of the charge and discharge of current to and from the capacitor C

connected

to the CF pin (pin 3) to determine the switching timing of the power MOSFET.

The IC is in constant voltage control by changing the on-period of the power MOSFET without making offperiod change while the IC is in normal (RCC continuous) operation mode. At that time, the on-period is controlled by directly changing the output pulse width of the oscillation circuit, and the maximum on-period can be adjusted with input voltage compensation by detecting the input voltage with the flow of current from the TR pin (TR source current). Refer to figure 2. When the IC is in standby mode (for light loads), the stable, efficient control of the IC is ensured by detecting the flow of current from the FB pin (I

) and changing the off-period for

a decrease in frequency. Refer to figure 3.

The following provides information on how to set on- and off-period.

• Setting the on-period

The output on-period is the discharge period when the CF pin is between the peak value oft V

(typical) and V

H-CF

An approximate on-period of the power MOSFET is obtained from the following formula. Refer to figure 2.

= CCF × (V

whereas, V

− VFB)/I

H-CF

= I

= (EIN × NB/NP − VZ)/R

= 4 V typ.

+ 250 µA typ.

VFB = 0.7 V typ. (I V

= 4 kΩ × IFB typ. (I

≤ 200 µA)

> 200 µA)

= 4 V

AN8027, AN8037 Voltage Regulators

■ Application Notes (continued)

[1] Operation descriptions (continued)

2. Oscillation circuit (continued)

• Setting the on-period (continued)

TON: On-period C

: Value of a capacitor connected to CF pin

: Voltage internally converted from feedback signal I

: CF upper limit voltage

H-CF

: On-period discharge current

: Flowing current at TR pin

: Voltage on primary winding

NB : Number of turns in the bias winding NP : Number of turns in the primary winding V

: Voltage on Zener diode connected to bias winding

: Value of a resistor connected to the TR pin

The power MOSFET is turned off if the voltage at the CLM pin reaches the pulse-by-pulse overcurrent

protection threshold voltage (i.e., −200 mV typical) when the overcurrent protection function of the IC is

operating.

TON is shortened because large E increases I

IN+

AN8027, AN8037

The minimum current is guaranteed to prevent a limitless increase in T

CF pin voltage

Current mirror

20 kΩ

= 4 V

H-CF

1 : 5

250 µA

Current mirror

ITR=I

typ.

Out GND

0 V

VCC − 1.5 V

Out pin voltage

Off On

0 V

Figure 2. On-period block diagram and control waveform

IN−

EIN; large I

TR(ION

); large

The maximum on-period can be used for overcurrent protection. When the input voltage is low, the maximum on-period overcurrent protection is possible. When the input voltage is high, the CLM pulse-by-pulse overcurrent protection is possible.

Voltage Regulators AN8027, AN8037

■ Application Notes (continued)

[1] Operation descriptions (continued)

2. Oscillation circuit (continued)

• Setting the off-period

The minimum off-period is the charge period from V An approximate minimum off-period of the power MOSFET is obtained from the following formula.

Refer to figure 3.

T C V V I

OFF1

OFF2

= CCF × V

OFF(min)

= {C V

TH(OFF)

OFF1

OFF2

: Minimum off-period

OFF(min)

: Value of a capacitor connected to the CF pin

: Voltage internally converted from feedback signal I

: Threshold voltage of VFB to extend off-period

TH(OFF)

TH(OFF)/IOFF1

× V

TH(OFF)

= 2.4 V typ. = 660 µA typ. = 160 µA typ.

≤ 0.6 mA)

/ I

} + {CCF × (VFB − V

OFF1

: Charge current until CF pin voltage increases from 0.2 V to 2.4 V : Charge current until CF pin voltage increases from 2.4 V to V

When the IC is in local resonance operation, the off-period is determined by the longer one of either the time required for the input voltage on the TR pin to drop below the threshold voltage or the minimum offperiod (T

) specified by the CCF.

OFF(min)

Thus the power MOSFET is in continuous on/off operation.

= 0.2 V (typical) to V

L-CF

) / I

TH(OFF)

OFF2

IN+

or VFB .

TH(OFF)

}(IFB > 0.6 mA)

H−CF

CF pin voltage

= 2.4 V

TH(OFF)

= 0.2 V

L2−CF

Out pin voltage

= 4 V

0 V

− 1.5 V

0 V

Current mirror

FBPC

20 kΩ

IFB < 0.6 mA

OFF(min)

OFF

AN8027, AN8037

1 : 5

= 660 µA typ.

OFF

< 0.6 mA)

= 160 µA typ.

OFF

> 0.6 mA)

OFF

Out

GND

IFB > 0.6 mA

= 4V

H−CF

CF pin voltage

= 2.4 V

TH(OFF)

= 0.2 V

L2−CF

− 1.5 V

Out pin voltage

0 V

OFF(min)

OFF

IFB; large T

OFF(min)

; large

0 V

Figure 3. Off-period block diagram and control waveform

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