Document
NCP1205
Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback
The NCP1205 combines a true Current Mode Control modulator and a demagnetization detector to ensure full Discontinuous Conduction Mode in any load/line conditions and minimum drain voltage switching (Quasi--Resonant operation, also called critical conduction operation). With its inherent Variable Frequency Mode (VFM), the controller decreases its operating frequency at constant peak current whenever the output power demand diminishes. Associated with automatic multiple valley switching, this unique architecture guarantees minimum switching losses and the lowest power drawn from the mains when operating at no--load conditions. Thus, the NCP1205 is optimal for applications targeting the newest International Energy Agency (IEA) recommendations for standby power.
The internal High--Voltage current source provides a reliable charging path for the VCC capacitor and ensures a clean and short startup sequence without deteriorating the efficiency once off.
The continuous feedback signal monitoring implemented with an Overcurrent fault Protection circuitry (OCP) makes the final design rugged and reliable. The PDIP--14 offers an adjustable version of the OVP threshold via an external resistive network.
Features
Natural Drain Valley Switching for Lower EMI and Quasi--Resonant
Operation (QR)
Smooth Frequency Foldback for Low Standby and Minimum Ripple
at Light--Load
Adjustable Maximum Switching Frequency Internal 200 ns Leading Edge Blanking on Current Sense 250 mA Sink and Source Driver Wide Operating Voltages: 8.0 to 30 V Wide UVLO Levels: 7.2 to 15 V Typical Auto--Recovery Internal Short--Circuit Protection (OCP) Integrated 3.0 mA Typ Startup Source Current Mode Control Adjustable Overvoltage Level These are Pb--Free Devices
Applications
High Power AC/DC Adapters for Notebooks, etc. Offline Battery Chargers Power Supplies for DVD, CD Players, TVs, Set--Top Boxes, etc. Auxiliary Power Supplies (USB, Appliances, etc.)
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MARKING DIAGRAM
8 1
PDIP--8 N SUFFIX CASE 626
8
1205P AWL
YYWWG
1
14 1
PDIP--14 P SUFFIX CASE 646
14
NCP1205P2 AWLYYWWG
1
16 1
16
SOIC--16 D SUFFIX CASE 751B
NCP1205DG AWLYWW
1
A WL YY, Y WW G
= Assembly Location = Wafer Lot = Year = Work Week = Pb--Free Package
ORDERING INFORMATION
Device
Package
Shipping†
NCP1205PG
PDIP--8 (Pb--Free)
50 Units/Rail
NCP1205P2G
PDIP--14 (Pb--Free)
25 Units/Rail
NCP1205DR2G
SOIC--16 2500/Tape & Reel (Pb--Free)
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D.
Semiconductor Components Industries, LLC, 2010
December, 2010 -- Rev. 10
1
Publication Order Number: NCP1205/D
HV 1 Demag 2
FB 3 Ct 4
8 VCC 7 Drive 6 Isense 5 GND
PDIP--8
NCP1205
PIN CONNECTIONS
HV 1
14 NC
NC 2 Demag 3
13 VCC 12 Drive
FB 4 Ct 5 OVP 6 NC 7
11 Isense 10 GND 9 NC 8 NC
PDIP--14
HV 1 NC 2 NC 3 Demag 4 FB 5 Ct 6 OVP 7 NC 8
16 NC 15 NC 14 VCC 13 Drive 12 Isense 11 GND 10 NC 9 NC
SOIC--16
PIN FUNCTION DESCRIPTION
Pin No. PDIP--8 PDIP--14 SOIC--16 Pin Name
1 1 1 HV
Function Startup rail
23 34 45
4
Demag
Zero primary--current
detection
5 FB Feedback signal to control the PWM
6 Ct Timing capacitor
5
10
11
GND
The IC’s ground
NA 6
7
OVP
Overvoltage input
6
11
12
Isense
The primary--current
sensing pin
7 12 13 Drv This pin drives the external switcher
8 13 14 VCC Powers the IC
1. PDIP--14 has different pinouts. Please see Pin Connections. 2. Pin 2, 7, 8, 9 and 14 are nonconnected on PDIP--14. 3. Pin 2, 3, 8, 9, 10, 15 and 16 are nonconnected on SOIC--16.
Description
Connected to the rectified HV rail, this pin provides a charging path to VCC bulk capacitor.
This pin ensures the restart of the main switcher when operating in free--run.
This level modulates the peak current level in free--running operation and modulates the frequency in VFM operation.
By adding a capacitor from Ct to the ground, the user selects the minimum/maximum operating frequency.
--
By applying a 2.8 V typical level on this pin, the IC is permanently latched--off until VCC falls below UVLOL.
This pin senses the primary current via an external shunt resistor.
The IC is able to deliver or absorb 250 mA peak currents while delivering a clamped driving signal.
A positive voltage up to 30 V maximum can be applied upon this pin before the IC stops.
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2
NCP1205
4x1N4007 R5 15
Universal Input
+C1 10 mF
* R10 R8 15 k 22 k
18 27 3 NCP1205P 6 45
R6 C12 4.7 k 1 nF
R2 D2 150 1N4148 + C14 22 mF
M2 MTD1N60E R4 10
D6 1N5819
L2 10 mH
C10 470 mF
10 V
+
+ 5V C11
100 mF 10 V
D7 5.1 V
IC4
SFH6156--2
R3 3.3
C13
R1 560
* Please refer to the application information section regarding this element. 1.5 nF Y1
Figure 1. Typical Application Example for PDIP--8 Version
4x1N4.