ON Semiconductor NCP1215 User Manual

© Semiconductor Components Industries, LLC, 2005

July, 2005 − Rev. 3

1 Publication Order Number:

NCP1215/D

NCP1215

Low Cost Variable OFF Time
Switched Mode Power
Supply Controller

The NCP1215 is a controller for low power off−line flyback
Switchemode Power Supplies (SMPS) featuring low size, weight and
cost constraints together with a good low standby power performance.
The operating principle uses switching frequency reduction at light
load by increasing the OFF Time. Also, when OFF T ime expands, the
peak current is gradually reduced down to approximately 1/4 of the
maximum peak current to prevent from exciting the transformer
mechanical resonances. The risk of acoustic noise is thus greatly
diminished while keeping good standby power performance.

A low power internal supply block also ensures very low current
consumption at startup without hampering the standby power
performance.

A special primary current sensing technique minimizes the impact
of SMPS switching on control IC operation. The choice of peak
voltage across the current sense resistor allows dissipation to be
further reduced. The negative current sensing technique offers
advantages over a traditional approach by avoiding the voltage drop
incurred by traditional MOSFET source sensing. Thus, the IC drive
capability is greatly improved.

Finally, the bulk input ripple ensures a natural frequency dithering
which smooths the EMI signature.

Features

• Pb−Free Package is Available

• Variable OFF Time Control Method

• Very Low Current Consumption at Startup

• Natural Frequency Dithering for Improved EMI Signature

• Current Mode Control Operation

• Peak Current Compression Reduces Transformer Noise

• Programmable Current Sense Resistor Peak Voltage

• Undervoltage Lockout

Typical Applications

• Auxiliary Power Supply

• Standby Power Supply

• AC−DC Adapter

• Off−line Battery Charger

1

8

SOIC−8
D SUFFIX
CASE 751

18

5

3
4

(Top View)

FB

CS

NC

PIN CONNECTIONS

7
6

2

NC

CT

GND

Gate

V

CC

MARKING

DIAGRAMS

FAA = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week

1

6

TSOP−6

(SOT23−6, SC59−6)

SN SUFFIX

CASE 318G

FAAYW

1

6

SOIC−8

1

3

FB

CS

2GND

CT

4

Gate

6

(Top View)

5

V

CC

TSOP−6

ORDERING INFORMATION

P1215
ALYW

Device Package Shipping

†

NCP1215DR2 SOIC−8 2500 Tape & Reel

NCP1215SNT1 TSOP−6

3000 Tape & Reel

†For information on tape and reel specifications,

including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification

s

Brochure, BRD801 1/D.

1

8

http://onsemi.com

NCP1215DR2G SOIC−8

(Pb−Free)

2500 Tape & Reel

NCP1215

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2

Figure 1. Typical Application

LineLine

N

+

FB

GND

CT
CS

Gate

Vcc

NC

NC

+

+

+

−

*

*If your application requires a gate−source resistor, please refer to design guidelines in this document.

Figure 2. Representative Block Diagram

Feedback Loop

Control

−

+

FB

+

−

Off−Time

Comparator

CT

Voffset

0−7 V

10 mA

12.5−50 mA

CS

+

−

GND

Current Sense Comparator

Reset

Set

Q

Q

Reference

Regulator

V

DD

I

ref

−

+

Undervoltage

Lockout

12/8.5 V

Gate

V

CC

Gate Driver

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Á

PIN FUNCTION DESCRIPTION

TSOP−6

SOIC−8

Symbol

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Description

4 1 FB The FB pin provides voltage feedback loop. The current injected into the pin determines the

primary switch OFF time interval. It also influences the peak value of the primary current.
3 2 CT Connection for an external timing programming capacitor.
1 3 CS The CS pin senses the power switch current.
2 4 GND Primary and internal ground.
6 5 Gate Output drive for an external power MOSFET.
5 6 Vcc Power supply voltage and Undervoltage Lockout.
7 7 NC Unconnected pin.
8 8 NC Unconnected pin.

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Á

MAXIMUM RATINGS

Rating

Symbol

Value

Unit

Power Supply Voltage V

cc

18 V

FB Pins Voltage Range V

FB

−0.3 to 18 V

CS and CT Pin Voltage Range V

in

−0.3 to 10 V

Thermal Resistance, Junction−to−Air (SOIC−8 Version)

R

q

JA

178 °C/W

Junction Temperature T

J

150 °C

Storage Temperature Range T

stg

−60 to +150 °C

ESD Voltage Protection, Human Body Model (Except CT Pin) V

ESD−HBM

2.0 kV

ESD Voltage Protection, Human Body Model for CT Pin V

ESD−HBM−CT

1.5 kV

ESD Voltage Protection, Machine Model (Except CT Pin) V

ESD−MM

200 V

ESD Voltage Protection, Machine Model for CT Pin V

ESD−MM−CT

150 V

Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit
values (not normal operating conditions) and are not valid simultaneously . If these limits are exceeded, device functional operation is not implied,
damage may occur and reliability may be affected.

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ELECTRICAL CHARACTERISTICS (V

CC

= 12 V, for typical values Tj = 25°C, for min/max values Tj = 0°C to +105°C, unless

otherwise noted.)

Characteristic Symbol Min Typ Max Unit

VOLTAGE FEEDBACK

Offset Voltage

V

offset

1.05 1.19 1.34 V

Maximum CT Pin Voltage at FB Current = 25 mA (Including V

offset

) V

CT−25mA

2.4 3.1 4.3 V

Maximum CT Pin Voltage at FB Current = 50 mA (Including V

offset

) V

CT−50mA

3.6 4.6 6.2 V

CT PIN − OFF TIME CONTROL

Source Current (CT Pin Grounded)

I

CT

8.0 9.8 11.5

mA

Source Current Maximum Voltage Capability V

CT−max

− 6.5 − V

Minimum CT Pin Voltage (Pin Unloaded, Discharge Switch Turned On) V

CT−min

− − 20 mV

CURRENT SENSE

Minimum Source Current (I

FB

= 180 mA, CT Pin Grounded)

I

CS−min

8.0 12.5 16

mA

Maximum Source Current (IFB = 0 mA, CT Pin Grounded)

I

CS−max

40 49 58

mA

Comparator Threshold Voltage V

th

15 42 80 mV

Propagation Delay (CS Falling Edge to Gate Output) t

delay

− 215 310 ns

GATE DRIVE

Sink Resistance (I

sink

= 30 mA) R

OL

25 40 90

W

Source Resistance (I

source

= 30 mA) R

OH

60 80 130

W

POWER SUPPLY

V

CC

Startup Voltage V

startup

− 12.5 14.2 V

Undervoltage Lockout Threshold Voltage V

UVLO

7.2 9.0 − V

Hysteresis (V

startup

− V

UVLO

) V

hys

2.2 3.5 − V

VCC Startup Current Consumption (V

CC

= 8.0 V) I

CC−start

− 2.8 6.5

mA

VCC Steady State Current Consumption

(C

GATE

= 1.0 nF, f

SW

= 100 kHz, FB open)

I

CC−SW

0.55 0.9 1.75 mA

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TYPICAL CHARACTERISTICS

−25

11.5

50

11.2

250

V

startup

, (V)

11.0

TJ, JUNCTION TEMPERATURE (°C)

11.6

TJ, JUNCTION TEMPERATURE (°C)

11.1

11.3

11.4

125

V

offset

, (V)

1.08

Figure 3. V

startup

Threshold vs. Junction

Temperature

Figure 4. V

UVLO

Threshold vs. Junction

Temperature

Figure 5. Operating Current Consumption vs.

Junction Temperature

Figure 6. Offset Voltage vs. Junction

Temperature

TJ, JUNCTION TEMPERATURE (°C)

Figure 7. Current Sense Source Current vs.

Junction Temperature

TJ, JUNCTION TEMPERATURE (°C)

Figure 8. Current Sense Threshold vs.

Junction Temperature

TJ, JUNCTION TEMPERATURE (°C)

1.12

1.00

1.16

1.20

75 100 −25

8.7

50

8.4

250

V

UVLO

, (V)

8.2

8.8

8.3

8.5

8.6

12

5

75 100

−25

0.985

50

0.970

250

I

CC−SW

, (mA)

0.960

0.990

T

J

, JUNCTION TEMPERATURE (°C)

0.965

0.975

0.980

125

75 100 −25 5025012

5

75 100

1.04

1.06

1.10

1.14

1.18

1.02

−25

48.0

50

46.5

250

I

CS−max

, (

m

A)

45.5

49.0

46.0

47.0

47.5

12575 100

48.5

−25

55

50

40

250

V

CS−th

, (mV)

30

65

35

45

50

12

5

75 100

60