DN06023/D Design Note – DN06023/D Universal AC 15 W 4 Cell Charger Device Application Input Voltage Output Power Topology I/O Isolation MBT3906 MC33340 NCP1055 NIS6111 4 Cell NiCd-NiMH Battery Charger Universal 90-264 Vac 15 Watt Flyback Optional Other Specifications Output Voltage Ripple Nominal Current Max Current Min Current Output 1 Output 2 Output 3 Output 4 5.9 Vdc max 125 mA 2.5 A 3.0 A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A PFC (Yes/No) NO Minimum Efficiency 80% Inrush Limiting / Fuse 750 mA fuse Operating Temp. Range Cooling Method/Supply Orientation 0 to +40° C Case Convection Circuit Description This four-cell nickel battery rapid charger is based on the very low cost gated oscillator PWM switcher. The MC33340 -dV/dt detector controls the charging profile. The rapid charge rate current level is set to the maximum by magnetic and the NCP1055 design. One problem common to all rapid chargers is the dynamic range from trickle charge to rapid rates. The 2.5 A rapid charge is about 100 times the 25 mA trickle. This design overcomes this by utilizing a timer with an approximate 1% duty cycle to achieve the time averaged 25 mA trickle charge. ON’s co-packaged discrete transistors perform the analog functions with very low cost and reasonable temperature stability. The CCM-DCM boundary is at 142 Vac. European operation will be in DCM while the US will be in CCM. The charger is shown with the optional optocoupler in blue for isolated circuits. For the lowest cost chargers with integrated case isolation barrier systems the optocoupler can be eliminated. Then tie the two DC returns together and U7-2 is connected to U7-4. April 2007, Rev. 1 The schematic shows optional Y caps in pink for systems with a three-wire power cord. The earth return provides additional margin for applications that require more EMI filtering or earth ground connection. Blocking diode D9 prevents reverse current from the battery flowing through the low power bias circuitry when the charger is powered off. Efficiency can be improved by eliminating the diode. The NIS6111 BERS rectifier can be used for D7 and D9 to improve efficiency about 7% but at slightly higher cost. Key Features y 2.5 Ampere fast charger. y Vdc limited open circuit output. y 100 kHz Switchmode gated oscillator. y Frequency dithering reduces EMI signature. y Rapid charge rate current dynamically limited. y Trickle charge rate is timer duty cycle controlled. y Very low standby power consumption. www.onsemi.com 1 DN06023/D Schematic April 2007, Rev. 1 www.onsemi.com 2 DN06023/D Magnetics Design Data sheet Project / Customer Description: Schematic Ref. Des: 4 Cell Charger For Ni-Cd, Ni-MH Differential Mode Inductor L1 Bobbin: Vertical 8-Pin Core: EE-42211 J Core Gap: none Inductance Magnetizing: 7.7 mH ±5% 100 kHz Pin 1-4, 5-8 Inductance Leakage: 110 uH ±5% 100 kHz Pin 1-4, 5-8 shorted. Windings (in order) Layer Winding W1 Turns Magnetics Inc. Size No of Wires Material 47 1 W1 8 23 awg 1 Isonol180 2 W1 8 23 awg 1 Isonol180 3 W1 8 23 awg 1 Isonol180 4 W1 8 23 awg 1 Isonol180 5 W1 8 23 awg 1 Isonol180 6 W1 7 23 awg 1 Isonol180 W2 47 1 W2 8 23 awg 1 Isonol180 2 W2 8 23 awg 1 Isonol180 3 W2 8 23 awg 1 Isonol180 4 W2 8 23 awg 1 Isonol180 5 W2 8 23 awg 1 Isonol180 6 W2 7 23 awg 1 Isonol180 4 kVac 1 s. HiPot: P-S Schematic April 2007, Rev. 1 Lead Pin-out www.onsemi.com 3 DN06023/D Magnetics Design Data sheet Project / Customer Description: Schematic Ref. Des: 4 Cell Charger For Ni-Cd, Ni-MH Common Mode Inductor L2 Bobbin: none Core: T 2/1.3/0.6 Core Gap: none Inductance Magnetizing: 51 uH ±5% 100 kHz Pin 1-2 Inductance Leakage: NA ±5% 100 kHz -. Windings (in order) Layer Winding Turns W1 1 General Purpose Size No of Wires Material 34 awg 5 Isonol180 34 W1 34 Magnetics Design Data sheet Project / Customer Description: Schematic Ref. Des: 4 Cell Charger For Ni-Cd, Ni-MH Output filter Inductor L3 Bobbin: none Core: T 1.2/0.83/0.5 Core Gap: none Inductance Magnetizing: 1.24 uH ±5% 100 kHz Pin 1-2 Inductance Leakage: NA ±5% 100 kHz -. Windings (in order) Layer Winding W1 1 April 2007, Rev. 1 Turns General Purpose Size No of Wires Material 22 awg 5 Isonol180 6 W1 6 www.onsemi.com 4 DN06023/D 1 Magnetics Design Data sheet Project / Customer Description: Schematic Ref Des: 4 Cell Charger For Ni-Cd, Ni-MH Transformer T1 Bobbin: Vertical 8-Pin Core: EE-43007 P Core Gap: TBD Inductance Magnetizing: 1.1 mH ±5% 100 kHz Pin 1-4 with 2-3 shorted. Inductance Leakage: 7 uH ±5% 100 kHz Pin 1-4, 2-3, 5-6-7-8 shorted. Windings (in order) Layer Winding W1 1 Magnetics Inc. Turns Size No of Wires Material 34 W1 17 23 awg 1 Isonol180 2 W1 17 23 awg 1 Isonol180 3 Tape 3 0.05 W2 4 5 W2 5 PVC Tape W3 5 23 awg 3 0.05 4 Isonol180 PVC 34 6 W3 17 23 awg 1 Isonol180 7 W3 17 23 awg 1 Isonol180 8 Tape 1 0.05 P-S 4 kVac 1 s. P-Core 4 kVac 1 s. S-Core 4 kVac 1 s. PVC HiPot: Schematic Lead Pin-out 1 © 2007 ON Semiconductor. Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its products at any time, without notice. Design note created by Dale Tittensor, e-mail: [email protected] April 2007, Rev. 1 www.onsemi.com 5