LD8526 LEADTREND | Alldatasheet
Document overview
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Technical content
Features
Suited for low side and high side flyback synchronous rectification in CCM, DCM and QR(valley lock) mode Suited for forward freewheeling rectification in CCM and DCM Self-supplying for operation with low output voltage and/or high–side rectification without an auxiliary winding. Suited for primary side with peak load function (max. frequency 130kHz) Suited for PD application, which output voltage range from 3V to 21V, and VCC range from 3V to 6V. Programmable turn-off level Fast turn-off total delay of 30ns 200A ultra-low green mode operation current Gate source/sink capability: 0.5A/-3A
Applications
Switching AC/DC adaptor and battery charger Open frame switching power supply
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018 Typical Application GND 5 DET VCC DRV LD8526 HVR VIN DC Output Fig. 1 Flyback Low Side Synchronous Rectification GND VCC DET VIN DRV LD8526 DC Output HVR Fig. 2 Flyback High Side Synchronous Rectification
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018 Pin Configuration SOT-26 (TOP VIEW) Y : Year code (D: 2004, E: 2005…..) W : Week code PP : Production code Z26 : LD8526 1 2 3 4 5 6 DRV GND VCC VIN HVR DET YWZ 26 pp
Ordering Information
Part number Package Top Mark Shipping LD8526 GL SOT-26 Green Package YWZ/26 3000 / tape & reel The LD8526 is ROHS compliant/ green packaged. Protection Mode Part number Int. OTP LD8526 Auto-Restart Pin Description PIN (SOT-26) NAME FUNCTION
1 DRV Driving pin, connector to GATE pin of MOSFET directly or through a resistor
2 GND Ground pin
3 VCC Supply voltage pin
4 DET Synchronous rectification detection
5 HVR HV linear regulator input
6 VIN External supply input
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018 GND HVR Int. OTP DET VDET_OFF S Q R Minimum on/off time DRV Green Mode Detect Driver Stage SR_ON Logic VBIAS IDET_OFF LDO VCC VIN LDO Block Diagram
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018 Absolute Maximum Ratings DET -1V ~ 200V HVR -1V ~ 200V VIN -0.3V ~ 30V VCC -0.3V ~ 7V DRV -0.3V~VCC+0.3V Maximum Junction Temperature 150C Storage Temperature Range -65C to 150C Package Thermal Resistance (SOT-26) 200C/W Power Dissipation (SOT-26, at Ambient Temperature = 85C) 200mW Lead temperature (Soldering, 10sec) 260C ESD Voltage Protection, Human Body Model (except of DET/HVR Pin) 2.5KV ESD Voltage Protection, Human Body Model (DET/HVR Pin) 1KV ESD Voltage Protection, Machine Model 250V Caution: Stresses beyond the ratings specified in “absolute maximum ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Recommended Operating Conditions Item Min. Max. Unit Operating Junction Temperature -40 125 C Supply Voltage VIN 24 V Supply Voltage VCC 3 6 V Power MOS Gate Threshold Voltage 1.5 4 V Operating Frequency 130 KHz VCC capacitor 2.2 F MOSFET Ciss (1) 1000 5500 pF Turn-Off Rgate (1) 0 5 Ω RDET 600 Ω Notes: 1. When MOSFET Ciss is the maximum value, turn-off RGATE must be the minimum value. On the contrary, when MOSFET Ciss is the minimum, turn-off RGATE must be the maximum.
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018
Electrical Characteristics
(TA = +25oC unless otherwise stated, VIN=12V) PARAMETER CONDITIONS SYMBOL MIN TYP MAX UNITS HVR (VIN Pin) HVR charge current HVR=30V, VCC=3.5V ICHG_HVR1 20 35 50 mA HVR=12V, VCC=3.5V ICHG_HVR2 10 20 30 mA Leakage current VHVR=200V IHVR_LK 50 µA Supply Voltage (VIN Pin) VIN charge current VIN=12V, VCC=3.5V ICHG_VIN 22 38 50 mA Supply Voltage (VCC Pin) UVLO (on) VCC_ON 2.8 3 3.2 V UVLO (off) VCC_OFF 2.8 V UVLO Hysteresis VCC_HYS 0.2 V VCC Operating Voltage HVR=12V VVCC_H1 4.5 5.8 6.8 V VIN=12V VVCC_H2 4.5 6.0 6.8 V Operating Current Vcc=5V, DET=65kHz, 4.7nF on GATE pin IVCC_OP1 2.2 3 mA Green mode IVCC_OP2 200 250 µA UVLO_OFF mode VCC=2.5v IVCC_OFF 25 µA Detection Reference (DET Pin) Turn-on voltage VDET_ON -400 -300 -150 mV Turn-off voltage (3) VDET_OFF 10 20 30 mV Turn-off compensation current IDET_OFF 85 100 115 µA Ring Reject Threshold VDET_R 1.3 1.6 1.8 V Ring Reject Threshold Hysteresis VDET_RHY 1.1 V Ring Reject Window TDET_WD 50 70 100 ns Leakage current VDET=200V IDET_LK 1 µA Max. Operating Limit (1) FSW_MAX 150 180 220 kHz
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018 PARAMETER CONDITIONS SYMBOL MIN TYP MAX UNITS Drive (DRV Pin) Total Turn-on delay time (2) TD_ON 65 ns Total Turn-off delay time (2) TD_OFF 25 ns Pseudo dead time TPDT 4 5 6 µs Output High Voltage Io=+10mA VDRV_H 4.4 4.7 V Output Low Voltage Io=-10mA VDRV_L 0.5 V Turn-off propagation delay Tp 15 ns Turn-on Rising time (2), drive voltage from 20%(2V) to 80%(8V) Tr 75 150 ns Turn-off Falling time (2), drive voltage from 80%(4V) to 20%(1V) Tf 13 30 ns Minimum On Time TMIN_ON 1.5 us Minimum Off Time TMIN_OFF 0.7 1 1.3 µs On Chip OTP (Over Temperature) Auto-Recovery OTP Level (1) TOTP 150 C OTP Hysteresis (1) TOTP_HYS 30 C Notes: 1. Guaranteed by design. 2. Load capacitance=4.7nF. 3. For avoiding SR being too late to turn off in CCM, RDET must be adjusted from 600R down to appropriate value.
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018 Typical Performance Characteristics
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018
Application Information
The LD8526 is a secondary side synchronous rectification driver IC for CCM and DCM operation. The LD8526 not only has excellent dead time control function for safety in load transient, but also only needs very low operation current in green mode. In addition, LD8526 can generate its own supply voltage through low output voltage or high side rectification applications to charge battery. Hence, LD8526 is suitable for PD application. LDO Charge Function LD8526 has two LDO (low drop-out regulator), which are used to provide VCC power. When LD8526 is applied in low side, VIN is connected to DC output and HVR is connected to SR MOSFET drain pin. Once the primary side power on and DC output is below 4.4V, VCC will be charged by HVR via LDO and VCC will keep at 5.8V at heavy load . As DC output exceeds 4.4V, VCC will be replaced by VIN to charge via LDO. When VIN increases, VCC also rises until 5.2V. When LD8526 is applied in high side, HVR is connected to SR MOSFET drain pin, too. However VIN is floating. VCC can only be charge by HVR via the LDO. And in heavy load, the VCC is always maintained at 5.8V. No matter LD8526 is applied in high side or low side, a capacitor must exist from VCC to GND to store the energy. Under Voltage Lockout (UVLO) and Enable Function An UVLO comparator is implemented in it to detect the voltage on the VCC pin. It w ill assure the supply voltage enough to turn on the LD8526 controllers and further to drive the synchronous rectifier. As shown in Fig. 15, t he UVLO(ON) and UVLO(OFF) are 3V and 2.8V respectively. To enable synchronous rectifier, the following conditions must be met: 1. VCC > UVLO(ON) 2. Exit green mode 3. DET > VDET_ON With these restrictions , synchronous rectifier always operates in stable condition. Therefore, some unstable transient, which are like turn -on, turn -off, output short, surge, ESD …etc., will not make synchronous rectifier unsafe when it works. UVLO(ON) UVLO(OFF) VCC DR V t t DET t VDET_ON Fig. 15 Green Mode Operation For improving the efficiency in light load conditions , LD8526 stops SR MOSFET driving function to reduce operation current, as shown in Fig. 16. DET pin detects system behavior, and the internal logic circuit sets DRV to high or low . Hence, LD8526 can enter/exit green mode normally, even under dynamic load.
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018 Pri. PWM DRV t t >1.2ms 16cycle <1.1msGreen mode detection pulse Enter Green Mode Leave Green Mode Leave Green Mode >1.1ms <1.1ms Fig. 16 Turn-on Phase After a negative voltage ( −300 mV typical) is sensed on the DET pin, the driver output voltage (Int. DRV, see Block Diagram) is made high and the internal MOSFET is switched on. After switch-on of the SR MOSFET, the input signal on the DET pin is blanked for 1.5s (typical). This will eliminate false switch-off due to high frequency ringing at the start of the secondary stroke. Turn-off Phase The DET pin has detection gate on time to do prediction gate pre-drop method (TON x 0.5 = TPREDICT), and adjusting VDS decreases gate driver voltage to 4V (typical). As soon as the DET voltage is above VDET_OFF, the driver output is pulled to ground. For avoiding SR being too late to turn off in CCM, the following condition must be met, as shown in Fig. 17. 10mV- X RI - V DETDET_OFFDET_OFF Where I DET_OFF = 100A, V DET_OFF = +20mV, X= thermal effect and parasitic inductance from trace & electronic components. Hence RDET must be from 600Ω down to find the appropriate turn-off time. The behavior of Int. DRV in DCM & CCM are shown separately in Fig. 18. DET Green Mode Detect SR_ ON Logic VBIAS SR_ MOS Drain RDET IDET_OFF VDET_OFF Fig. 17 ISD DET t t Int. DRV t ISD DET t t Int. DRV t VDET_OFF DCM CCM TPREDICT VDET_OFF TON TON TPREDICT Fig. 18 On-Chip OTP - Auto Recovery An internal OTP circuit is embedded inside the LD8526 to provide the worst-case protection for this controller. When the chip temperature rises and it’s higher than the trip OTP level, the output will be disabled until the chip is cooled down below the hysteresis window.
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018
Package Information
Dimension in Millimeters Dimensions in Inches Min Max Min Max A 2.692 3.099 0.106 0.122 B 1.397 1.803 0.055 0.071 D 0.300 0.500 0.012 0.020 F 0.95 TYP 0.037 TYP H 0.080 0.254 0.003 0.010 I 0.050 0.150 0.002 0.006 J 2.600 3.000 0.102 0.118 M 0.300 0.600 0.012 0.024 θ 0° 10° 0° 10° Important Notice Leadtrend Technology Corp. reserves the right to make changes or corrections to its products at any time without notice. Customers shou ld verify the datasheets are current and complete before placing order.
Leadtrend Technology Corporation www.leadtrend.com.tw LD8526-DS-00 August 2018
Revision History
REV. Date Change Notice 00 08/31/2018 Original Specification