Secondary-side Control for Energy-saving AC Adaptors Monolithic IC MM1529

Transcription

1 Secondary-side Control for Energy-saving AC Adaptors Monolithic IC MM1529 Outline This IC is a secondary-side control IC for AC adaptors with energy-saving mode, and switches to energysaving mode when there is no load current flowing to reduce power consumption in an AC adaptor. When a load current flows in normal mode, it enters to normal mode to power the load. To control the oscillator on the primary side, this IC controls two photocouplers, performs constant-voltage/constant-current control, and switches between energy-saving and normal modes. Features 1. Automatic switching between energy-saving mode and normal mode 2. Current consumption (energy-saving mode) 60µA 3. Current consumption (normal mode) 1.7mA 4. Reference voltage (internal/output inversion voltage) 1.250V±25mV 5. Controls the oscillator on the primary side using two photocouplers. 6. Photocouplers are use for constant-voltage/constant-current control and switching between energy-saving and normal modes. Package SOP-8D Applications 1. AC adaptors (cell phones, movies, PDA, note PCs, and more) 2. Chargers (cell phones, movies, PDA, note PCs, and more) Pin Connetion Diagram SOP-8D 1 PO1 2 PO2 3 GND 4 CS 5 REF 6 OUT 7 CNT 8 VCC

2 Block Diagram RLS L1 Load detection resistor Secondary transformer PO2 PO1 VCC 2 1 GND 3 RL1 PC2 For load detection RL2 PC1 For rated current rated voltage VCC 8 CNT 7 RLB OUT 6 Input/output error control (0.2V) Reference voltage drop REF 5 Voltage drop detection (1.0V) CS ROS1 Load connect detection (0.2V) REF control (1.25V) Rated current control (0.1144V) 4 ROS2 COUT RCS Rated current detection resistor

3 Terminal Explanation Pin No. Pin name Function Internal equivalent circuit Rated current rated voltage control photocoupler LED drive PO1 pin.connects cathode side of diode. 2 PO2 Output load detection photocoupler LED drive pin. Connects cathode side of diode. 3 GND Ground pin. Overcurrent detection pin. 4 CS Doubles as output- pin. Connects overcurrent resistor to GND pin. Reference voltage input pin. Connects ROS1 resistor to the 5 REF OUT pin and ROS2 resistor to GND pin to control output pin. Output voltage={1+ (ROS1/ ROS2)} 1.25 Output +pin. Connects load detection resistor to Vcc pin and connects PNP 6 OUT power transistor collector. 7 CNT PNP power transistor control pin. Connects to PNP power transistor base. 5 4 VCC 6 VCC 7 +Power supply pin. Doubles as load detection pin. Connects load detection resistor to OUT pin 8 VCC and connects PNP power transistor emitter V

4 Absolute Maximum Ratings (Ta=25 C) Item Symbol Rating Unit Storage temperature TSTG -40~+125 C Operating temperature TOPR -30~+85 C Supply voltage VCCmax. -0.3~+18 V Power dissipation PD 300 (Alone) mw Recommended Operating Conditions Electrical Characteristics Item Symbol Rating Unit Operating temperature TOPR -30~+85 C Supply voltage VOP +2.5~+12 V (VCC=5.0V, Ta=25 C Unless otherwise specified) Item Symbol Test Conditions Min. Typ. Max. Unit Current consumption 1 ICC1 VREF=1.2V 60 µa (energy-saving mode) VCS=0V VOUT=4.7V Current consumption 2 ICC2 VREF=1.2V ma (normal mode) VCS=0V Voltage control RL1=500Ω Output inversion voltage VREFH VREF:1.1V H RL2=1kΩ V VCS=0V RL3=Ω REF input voltage IREF VREF=1.1V 15 na VCS=0V VCC=4V 12V Power supply voltage removal PSRR1 VREF=1.5V db VCS=0V RL1=5kΩ P01 output inflow current IPO1-V VREF=1.5V 5 17 ma VCS=0V VPO1=0.5V

5 Item Symbol Test Conditions Min. Typ. Max. Unit Rated current control VOUT=4.7V RL1=500Ω Output inversion voltage 1 VCS1 VREF=1.2V RL2=1.2kΩ mv (rated current control) VCS : L H RL3=1.4kΩ VCC=2.0V Output inversion voltage 2 VOUT=0V RL1=500Ω (rated current control) VCS2 VREF=1.2V RL2=1.2kΩ VCS : L H RL3=1.4kΩ mv CS input current ICS VREF=1.2V 15 na VCS=0.1V VCC=4V 12V Power supply voltage removal PSRR2 VREF=1.2V db VCS=VCS1-mV RL2=5kΩ VOUT=4.7V P01 output inflow current IPO1-I VREF=1.2V 5 17 ma VCS=0.2V VPO1=0.5V Input/output error control RLS=4.7kΩ Input/output error VLS RO=5kΩ mv control voltage RLB=Ω VOUT=4.7V CNT output inflow current ICNT VREF=1.2V 5 30 ma VCS=0V VCNT=0.8V OUT input current IOUT VREF=1.2V 2 na VCS=0V Load detection L RL1=500Ω Load detection voltage VLSP1 VREF=1.2V RL2=1kΩ mv Energy-saving detection voltage (load detection release voltage) VCS=0V RL3=Ω VOUT=L 5.0V RL1=500Ω VLSP2 VREF=1.2V RL2=1kΩ mv VCS=0V RL3=Ω RL1=500Ω Voltage drop detection VREFL VREF=1.2V L RL2=1kΩ V VCS=0V RL3=Ω VOUT=4.7V PO2 output inflow current IPO2 VREF=1.2V ma VCS=0V VPO2=0.5V

6 Operation Description MM1529 Block Diagram Vcc-OUT voltage VCC 4.7kΩ OUT RLS Supply transistor Load current RLB Input/output error control Load connection detection PO2 drive Load detection data transmission photocoupler PC2 1. Description of Blocks Voltage drop detection Rated voltage control PO1 drive REF Rated current control ROS1 CS ROS2 Load RCS Rated voltage rated current control photocoupler PC1 (1) Input/output error control Controls Tr base current supplied from the CNT pin when load is detected and the voltage between Vcc-OUT (supply Tr VCE voltage) falls below the setting voltage VLS (200mV). (2) Load connection detection PO2 pin goes from OPEN to LOW when load current is the same as setting voltage VLSP1 (200mV) and photocoupler PC2 goes on. This releases AC adaptor primary side switching prohibition and supply status begins. Also,detection voltage is changed in load current increasing and decreasing directions. (hysteresis : VLSP1 = 200mV VLSP2 = 115mV) (3) Voltage drop detection In order to carry out intermittent oscillation on the secondary side, in energy-saving mode (load 30µA or less), the setting is such that energysaving detection is released when REF pin voltage = 1.0V or less (when output voltage reaches 4V when set at 5V). This causes secondary side output voltage to oscillate intermittently between 5V 4V. (4) Rated current control When voltage between CS and GND pins reaches setting voltage VCS1 (0.1144V), external rated current detection resistor RCS causes P01 pin to go from OPEN to LOW, and rated voltage rated current control photocoupler PC1 goes on. This starts CC mode and controls VCS1 voltage to V. (5) Rated voltage control Controls P01 so that REF pin voltage = 1.25V. This starts CV mode.

7 2. Mode Settings AC adaptors using MM1529 have the following four mode controls. Mode switching design is explained below. (PO1:Control) (PO2:Open) Energy-saving mode CV mode (PO1:Control) (PO2:Low) {1+(ROS1/ROS2)} VREFH Output voltage (V) (1) Load detection/energy-saving detection (RLS adjustment method) Load detection current and energy-saving detection current can be set by load detection resistor RLS. When used at 4.7kΩ, it is designed to switch when current flowing on RLS is > 43µ. However, R0S1 and R0S2 currents must be subtracted for actual detection. (Must be subtracted from Graph 1 results.) [Calculation formula] Load detection current = ( VLSP1/RLS) - (output voltage/(r0s1+/r0s2)) Energy-saving detection current = ( VLSP2/RLS) - (output voltage/(r0s1+/r0s2)) Energy-saving detection current(µa) Energy-saving detection (load detection release) ( VLSP2/RLS)-IOS* ( VLSP1/RLS)-IOS* 0 VCS2/RCS Load Detection VCS1/RCS Relationship between RLS load detection value and energy-saving detection value CC mode (PO1:Control) (PO2:Low) (PO1:Control) (PO2:Low) Load current(a) RLS load detection resistance (kω) Graph 1 *IOS=Output voltage/(ros1+ros2) Load Detection Energy-saving detection

8 (2) Rated current detection (RCS adjustment method) Rated current control value can be set by rated current detection resistor RCS. When used at 0.22Ω, it is designed to switch to rated current operation at 520mA. [Calculation formula] Rated current control = VCS1/RCS (VCS1 = V) (ma) Rated current detection current Relationship between rated current detection resistor RCS and detection value 0.22Ω RCS rated current detection resistance (Ω) Graph 2 (3) Output voltage (R0S1, R0S2 adjustment method) Precautions with regard to R0S1 and R0S2 output voltage detection resistance The REF pin is controlled to 1.25V, so output voltage can be designed using the resistance ratio between R0S1 and R0S2. At this time, R0S1 + R0S2 current is that added to load detection, so it must be set lower than load detection current. [Calculation formula] Output voltage = {1 + (R0S1/R0S2)} 1.25 R0S1 + R0S2 current value (ua) 1 Relationship between R0S1 and R0S2 output voltage detection resistance and current 5V Output V Output ROS1 + ROS2 resistance value (kω) Graph

9 Load Detection Load current increase Load current 0mA 5V Load detection current=( VLSP1/RLS)-IOS Energy-saving detection current=( VLSP2/RLS)-IOS 5.2V VLSP1 (0.2V) Vcc pin Out pin 0V PO2 pin OPEN Low CNT pin OPEN Control OUT pin voltage Vcc pin voltage Energy-saving Detection (load detection release) Load current decrease Load current Detection current=( VLSP1/RLS)-IOS Vcc pin Out pin 0mA 5V 0V Energy-saving detection current=( VLSP2/RLS)-IOS 5.2V VLSP2(0.1144V) OUT pin Vcc pin voltage voltage PO2 pin OPEN Low CNT pin OPEN Control

10 Application Circuit F1 1.5A/125V ACV SA1 22M 0.1µ L1 2200p D1 8.2µ 0.1µ 1M 6.8 R1 R5 Q2 k 680k 2.2M 270k R16 R2 R3 R4 2200p Q µ R6 C R C4 Q1 T1 D2 C5 470µ D3 L2 220 C6 220µ R9 1k R 2.7k R15 Q4 R8 MM1529 C8 R µ 0.22±1% PH1 PH2 220 R12 150p C 240k 82k R13 R14 220µ OUTPUT DC4.9V 520mA

11 Characteristics Diagram PO1 pin current characteristics PO2 pin current characteristics PO1 pin current IPO1(mA) CNT pin current ICNT(mA) VCC=5V 50 VCC=4V 40 VCC=3V 30 VCC=2V 20 VCC=1.8V VCC=1.6V VPO1(V) CNT pin current characteristics Reference voltage VREFH(V) VCC=5V 50 VCC=4V 40 VCC=3V VCC=2.7V VCC=2.5V VCNT(V) Reference voltage temperature response (VCC=5V) Temperature( C) PO2 pin current IPO2(mA) Reference voltage VREFH(V) 70 VCC=5V 60 VCC=4V 50 VCC=3V 40 VCC=2V VCC=1.8V VCC=1.6V VPO2(V) Reference voltage - current voltage characteristics Current consumption 1(uA) Current voltage Vcc(V) Current consumption 1 (energy-saving) temperature response (VCC=5V) Temperature( C) Current consumption 2 temperature response (VCC=5V) Current consumption 2(uA) Temperature( C)