Datasheet AS2214N Datasheet (ASTEC)

AS2214

Primary Side PWM Controller

Features

Low Startup Current

•

Bulk and AC sensing

•

Soft Start

•

Single-start or auto-restart

•

modes

Oscillator trimmed for precision

•

duty cycle clamp

Standard temperature range

•

extended to 105°C

Remote on / off control

•

Buffered Ramp for slope

•

compensation

Standard current mode control

•

Description

The AS2214 is a full featured, pulse width modulation controller. Based on an improved AS3842, the AS2214 provides additional features that reduce component count and improve specifications in a wide range of power supply designs. The added functionality includes AC power and bulk voltage sensing, over-voltage input, as well as the ability to latch off or bounce through different fault conditions.

The PWM function is controlled by the current sense comparator for normal current mode control and a second comparator for voltage mode soft start. A buffered RAMP signal is available for slope compensation without loading the oscillator. The output stage is a high current totem pole output that sees only 85 ns delay from the PWM comparator.

The AS2214 requires less than 10µA of startup current. The undervoltage lockout (UVLO) thresholds are nominally 13.8V for turn on and 8 V for turn off. A precision 2.5 V bandgap reference serves as an input for the error amplifier. The oscillator discharge current is trimmed to provide guaranteed duty cycle clamping.

Pin Configuration

—

Top view

1V

CC

2V

REG

3COMP BOK

4V

FB

5ISNS ACP

6SS OV

7RAMP RT/CT

14

OUT

13

GND

12

11

LEN

10

9

8

Ordering Information

Package Temperature Range Order Code

14-Pin Plastic DIP 0 to 105° C AS2214N

ASTEC Semiconductor

83

AS2214

Functional Block Diagram

2V 5

AC

DETE C T

V

REG

50µA

3V 95

2V 5

ACP

LEN

BOK

OV

ISNS

(LEN)

6V

(BULK_UV )

(CLR)

(OV )

Primary Side PWM Controller

5V enable

SS LOGIC

(RUN)

UVLO

5V R eg.

V

REG

6µA

V

SS

CC

REG

COMP

V

FB

2V 5

RT/CT

ASTEC Semiconductor

2R

1V

R

OSC

x1RAMP

CM PWM

SS P W M

(BLA NK)

(PWM)

V

CC

OUT

GND

84

Primary Side PWM Controller

AS2214 Soft Start Logic

AS2214

ENBL

SS

Q

•Q

ENBL

S

PRESET

R

Started

Q

•Q

ENBL

R

PRESET

S

Faulted

Q

•Q

R

PRESET

S

VOV

PWM_Disable

6µA

REG

V

2V7

Latch_bias

REG

V

Preset S R Q •Q

0---00

ENABL

ASTEC Semiconductor

10010

00001

1- 1010

1- 0101

1- 00Q•Q

1- 1100

LEN

OV

Q

•Q

ENBL

REG

V

2V5

1V7

OV

PRESET

S

R

3V9

2V5

BOK

85

AS2214

Primary Side PWM Controller

Pin Function Description

Pin Number Function Description

1VCCPositive supply voltage for the IC. 2V

REG

Output of 5V series regulator.

3 COMP This pin is the error amplifier output. Typically used to provide loop compensation to

maintain VFB at 2.5 V.

4V

FB

Inverting input of the error amplifier. The non-inverting input is a trimmed 2.5 V bandgap reference.

5 ISNS A voltage proportional to inductor current is connected to this pin. The PWM uses this

information to terminate the gate drive of the output.

6 SS This pin provides a 6µA current source to linearly charge an external capacitor. This pin

is compared to the RAMP pin in the soft start comparator, terminating output pulses when RAMP goes above the SS voltage.

7 RAMP This pin is a level-shifted and buffered oscillator signal used to provide slope compensa-

tion to the current sense signal. The pin also serves as the non-inverting input of the softstart comparator.

8 RT/CT Oscillator frequency and maximum duty cycle are set by connecting a resistor (R

T

) to

VREG and a capacitor (CT) to ground.

9 OV This pin latches SS low when pulled above 2.5 V. The latch can be reset by pulling

OV above 4 V then back to ground. 10 ACP This pin detects the presence of AC signal and drives LEN high. 11 LEN This pin must be high to enable starting. The pin can also clear all latches by going low

then high. 12 BOK This pin monitors the bulk voltage through a resistor divider and, when BOK exceeds

2.5 V, provides a 50µA current source for hysteresis. When BOK drops below 2.5V, SS

is pulled low and the hysteresis current is turned off. Auto-restart after a brown-out is

possible. 13 GND Circuit common ground. 14 OUT This totem pole output is designed to directly drive a power MOSFET switch capable of

sourcing and sinking peak currents up to 1 A.

ASTEC Semiconductor

86

Primary Side PWM Controller

AS2214

Absolute Maximum Ratings

Parameter Symbol Rating Unit

Reference Current I Output Current I Supply Voltage V Output Voltage V Continuous Power Dissipation at 25° CP Junction Temperature T Storage Temperature Range T Lead Temperature, Soldering 10 Seconds T

Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.

REF OUT

CC

OUT

D J

STG

L

200 mA

1A 20 V 20 V

500 mW 150 °C

–65 to 150 °C

300 °C

Recommended Conditions

Parameter Symbol Rating Unit

Supply Voltage V Oscillator F

CC

OSC

10 - 15 V 50 - 250 kHz

Typical Thermal Resistance

Package θJA θJC Typical Derating

14L PDIP 85° C/W 40° C/W 11.7 mW/°C

Electrical Characteristics

Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are V BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, V

Parameter Symbol Test Condition Min Typ Max Unit Error Amplifier

Input Voltage V Input Bias Current I Voltage Gain A Transconductance G Unity Gain Bandwidth GBW 0.8 1.2 MHz Power Supply Rejection Ratio PSRR 12 ≤ VCC ≤ 18 V 60 70 dB Output Sink Current I Output Source Current I Output Swing High I Output Swing Low I

BIAS

VOL

COMPL

COMPH

COMPL

TJ = 25°C 2.465 2.500 2.535 V

FB

2 ≤ V

m

VFB = 2.7 V; V VFB = 2.3 V; V VFB = 2.3 V; RL = 15 Ω to GND 5 5.5 V VFB = 2.7 V; RL = 15 Ω to V

≤ 4 V 65 90 dB

COMP

should be raised above 18 V prior to test.

CC

-0.1 -1 µA

1 mA/mV

= 1.1 V 2 6 mA = 5 V 0.5 1.0 mA

REG

0.7 1.1 V

= 15 V;

CC

ASTEC Semiconductor

87

AS2214

Primary Side PWM Controller

Electrical Characteristics (cont’d)

Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are V BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, V

should be raised above 18 V prior to test.

CC

Parameter Symbol Test Condition Min Typ Max Unit 5 V Regulator

Output Voltage V

REG

Line Regulation PSRR 12 ≤ V Load Regulation 1≤ I Temperature Stability TC

REG

I

= 1 mA, TJ= 25° C 4.90 5.00 5.10 V

REG

≤ 18 V 5 15 mV

CC

≤ 20mA 5 15 mV

REG

0.2 0.4 mV/°C Total Output Variation Line, Load,Temperature 4.85 5.15 V Long-Term Stability Over 1,000 hrs at 25°C525mV Output Noise Voltage V Maximum Source Current I

NOISE

MAX

10 ≤ f ≤ 100kHz, TJ = 25°C50µV V

= 4.8 V 30 120 180 mA

REG

Oscillator

Initial Accuracy F

OSC

Voltage Stability 12 ≤ V Temperature Stability TC Amplitude V

OSC

Upper Trip Point V Lower Trip Point V Discharge Current I

DSC

TJ =25°C 108 120 132 kHz

≤ 18 V 0.2 1 %

CC

T

F

≤ TJ ≤ T

MIN

MAX

5%

VRT/CT peak-to-peak 1.55 V

H

L

2.80 V

1.25 V

7.50 8.70 9.50 mA Duty cycle Limit RT =680 Ω, CT =10nF, TJ =25°C465054% Over-Temperature Shutdown T

OT

140 °C

Soft Start Comparator

SS Charge Current I SS Discharge Current I SS Lower Clamp V RAMP High Level V RAMP Low Level V

SS

Dsc

SS Low

RAMPHTJ

RAMPLTJ

SS V

V

≤ V

SS

= 1 V, V

SS

RAMP

> 2.5V 2 8 mA

OV

-4 -6 -10 µA

0.6 V =25°C 2.15 V =25°C 0.6 V

RAMP Levels TC Note: RAMP wavefrom is the same as -2 mV/°C

the RT/CT wavefrom, but level shifted

down one diode drop RAMP Sink Current I RAMP Source Current I Propagation Delay to Output t

RAMPL

RAMPH

PB

TJ =25°C –0.1 –0.2 mA

TJ =25°C1mA

85 150 ns

= 15 V;

CC

ASTEC Semiconductor

88

Primary Side PWM Controller

AS2214

Electrical Characteristics (cont’d)

Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are V BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, V

should be raised above 18 V prior to test.

CC

Parameter Symbol Test Condition Min Typ Max Unit Housekeeping

BOK UV Threshold V BOK UV Hysteresis Current I BOK Input Bias Current I OV Threshold V OV Clear Threshold V OV Reset Threshold V OV Bias Current I

UV V

BOK

HYST BOKVBOK

OFF BOKVBOK

OV

OVH

OVL

BIAS OVVREG

REG

= 5 V 2.500 2.537 2.575 V = 2.6 V 42 50 58 µA = 2.4 V 0.1 1.0 µA

2.50 2.80 3.10 V

3.80 4.00 4.50 V

1.10 1.75 2.20 V

= 5 V, V

≤ OV Threshold -1 -0.2 1 µA

OV

* For Vov > OV Reset Threshold,

see characteristic curve ACP Voltage V ACP Voltage V LEN Charge Current I LEN Charge Current I Minimum Voltage for LEN V

ACP

LEN

LEN MIN

I

= 10 µA 1.3 V

ACP

I

= -10 µA -1.2 V

ACP

I

= 10 µA; V

ACP

I

= -10 µA; V

ACP

= 0 V -30 -45 -65 µA

LEN

= 0 V -30 -50 -65 µA

LEN

3.6 4.5 V

Functionality LEN Logic Reset Voltage V

LEN Regeneration Current I LEN Clamp V LEN Bias Current I

BIAS LENVLEN

LEN

LENrgn

LEN

This level reflects one diode drop of 3.0 V

hysteresis from V

LEN min

-10 µA

I

= 5 µA 5.2 5.9 6.6 V

ACP

= 5 V, I

= 0 µA8µA

ACP

* For LEN input current over full

range, see characteristic curve.

Current Sense Comparator

Transfer Gain AV I

Level Shift V

SNS

Maximum Input Signal V Power Supply Rejection Ratio PSRR 12 ≤ V Input Bias Current I Propagation Delay to Output t

BIAS

PB

ISNS

LS

-0.2 ≤ V

V

ISNS

COMP

≤ 0.8 V 2.85 3.00 3.15 V/V

ISNS

= 0 V 1.50 V

=+5 V 1.00 1.08 1.20 V

≤ 18 V 70 dB

CC

-1 -10 µA

85 150 ns

= 15 V;

CC

ASTEC Semiconductor

89

AS2214

Primary Side PWM Controller

Electrical Characteristics (cont’d)

Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are V BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, V

should be raised above 18 V prior to test.

CC

Parameter Symbol Test Condition Min Typ Max Unit Under Voltage Lockout

Startup Threshold V Minimum Operating Voltage V

(ON) 12.5 14.0 15.8 V

CC

(OFF) 7.3 8.0 8.5 V

CC

after Trun-on Startup Current I Startup Current I Operating Supply Current I Maximum Operating Supply V

CC

CC Max

VCC = 12 V; V VCC = 12V; I

ACP

= V

ACP

= 0 V 2 10 µA

LEN

= 5 µA 225 300 µA

12 20 mA

18 V

Voltage Output Impedance to GND in Z

OUT

VCC = 6 V 22.0 kΩ

UVLO State

Output

Output Low Level V Output Low Level V Output High Level V Output High Level V Rise Time t Fall Time t Maximum Duty Cycle D Minimum Duty Cycle D

MAX

MIN

I

OL

OH

R

F

= 20 mA 0.1 0.4 V

SINK

I

= 150 mA 1.5 2.2 V

SINK

I

= 20 mA 13 13.5 V

SOURCE

I

= 150 mA 12 13 V

SOURCE

CL = 1 nF 50 150 ns CL = 1 nF 50 150 ns

94 97 100 %

0 %

= 15 V;

CC

ASTEC reserves the right to make changes without further notice to any products described herein to improve reliability, function, or design. ASTEC does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights or the rights of others. ASTEC products are not authorized for use as components in life support devices or systems intended for surgical implant into the body or intended to support or sustain life. Buyer agrees to notify ASTEC of any such intended end use whereupon ASTEC will determine availability and suitability of its products for the intended use. ASTEC and the ASTEC logo are trademarks of ASTEC (BSR) PLC.

ASTEC SEMICONDUCTOR

255 Sinclair Frontage Road • Milpitas, California 95035 • Tel. (408) 263-8300 • FAX (408) 263-8340

ASTEC Semiconductor

90