GS60100高耐压60V输入LED驱动

HIGH ACCURACY 1A, 60V LED DRIVER WITH INTERNAL SWITCH Description The GS60100 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 6V and 60V and provides an externally adjustable output current of up to 1A. Depending upon supply voltage and external components, this can provide up to 48 watts of output power. The GS60100 includes the output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. Output current can be adjusted above, or below the set value, by applying an external control signal to the 'ADJ' pin. The ADJ pin will accept either a DC voltage or a PWM waveform. Depending upon the control frequency, this will provide either a continuous (dimmed) or a gated output current. Soft-start can be forced using an external capacitor from the ADJ pin to ground. Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches the device into a low current standby state. Pin Assignments Typical Application Circuit Features • Typically better than 0.8% output current accuracy • Available in thermally enhanced SOP8 package • Simple and with low part count • Single pin on/off and brightness control using DC voltage or PWM • PWM resolution up to 900:1 • High efficiency (up to 95%) • Wide input voltage range: 6V to 60V • Inherent open-circuit LED protection Applications • Low voltage halogen replacement LEDs • Automotive lighting • Low voltage industrial lighting • LED back-up lighting • Illuminated signs • Emergency lighting • SELV lighting • LCD TV backlighting • Refrigeration lights . (TOP VIEW) SO-8-EP 4 6 5 1 72 8 3 LX GND GND ADJ VIN GND GND ISENSE VIN ISENSE LX GND GS60100ADJ VIN (24V) Rs 0.2V 10UF/100V C1 GND 100nF D1 L1 IOUTnom = 0.2/RS 2,3,6,7 4 8 5 1 SS310 GS60100 1 TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn 820uH Block Diagram Figure 1 Pin connection for SOP-8EP package Pin Description Name SO8-EP Description LX Drain of NDMOS switch GND Ground (0V) ADJ Multi-function On/Off and brightness control pin: • Leave floating for normal operation.(VADJ = VREF = 1.25V giving nominal average output current IOUTnom = 0.2V/RS) • Drive to voltage below 0.2V to turn off output current • Drive with DC voltage (0.3V < VADJ < 2.5V) to adjust output current from 25% to 200% of IOUTnom • Connect a capacitor from this pin to ground to set soft-start time. Soft start time increases approximately 0.2ms/nF ISENSE Connect resistor RS from this pin to VIN to define nominal average output current IOUTnom = 0.2V/RS (Note: RSMIN = 0.2V with ADJ pin open-circuit) VIN Input voltage (6V to 60V). Decouple to ground with 4.7µF of higher X7R ceramic capacitor close to device Low voltage detector Voltage regulator LX MN L1 D1 ISENSE Adj Gnd VIN VIN 50K 20K 1.25V 1.35V 0.2V 600KHz + - + - + - R4 R5 R2 R3 R1 2 4 8 5 1 D1 + - RS C1 4.7mF 5V 1 2, 3, 6, 7 4 5 8 GS60100 2 TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn Absolute Maximum Ratings (Voltages to GND Unless Otherwise Stated) Symbol Parameter Rating Unit VIN Input Voltage -0.3 to +60 (65V for 0.5 sec) V VSENSE ISENSE Voltage +0.3 to -5 (measured with respect to VIN) V VLX LX Output Voltage -0.3 to +60 (65V for 0.5 sec) V VADJ Adjust Pin Input Voltage -0.3 to +6 V ILX Switch Output Current 1.25 A PTOT Power Dissipation (Refer to Package thermal de-rating curve on page 26) SOT23-5; 1 DFN; 1.8 W TOP Operating Temperature -40 to 125 °C TST Storage Temperature -55 to 150 °C TJ MAX Junction Temperature 150 °C These are stress ratings only. Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability. Thermal Resistance Symbol Parameter Rating Unit SO-8-EP θJA Junction to Ambient 45 °C/W ΨJB Junction to Board - - θJC Junction to Case 7 Electrical Characteristics (Test conditions: VIN = 24V, Tamb = 25°C, unless otherwise specified.)(a) Symbol Parameter Condition Min. Typ. Max. Unit VIN Input voltage See note (b) 6 60 VSU Internal regulator start-up threshold 4.85 5.2 V VSD Internal regulator shutdown threshold 4.4 4.75 V IINQoff Quiescent supply current with output off ADJ pin grounded 65 108 µA IINQon Quiescent supply current with output switching(C) ADJ pin floating, L=68mH, 3 LEDs, f=260kHz 1.6 mA VSENSE Mean current sense threshold voltage (Defines LED current setting accuracy) Measured on ISENSE pin with respect to VIN VADJ=1.25V; VIN=18V 195 200 205 mV VSENSEHYS Sense threshold hysteresis ±15 % ISENSE ISENSE pin input current VSENSE = VIN -0.2 4 10 µA VREF Internal reference voltage Measured on ADJ pin with pin floating 1.25 V DVREF/DT Temperature coefficient of VREF 50 ppm/° C VADJ External control voltage range on ADJ pin for DC brightness control (d) 0.3 2.5 V VADJoff DC voltage on ADJ pin to switch device from active (on) state to quiescent (off) state VADJ falling 0.15 0.2 0.27 V Notes: (a) Production testing of the device is performed at 25°C. Functional operation of the device and parameters specified over a -40°C to +105°C temperature range, are guaranteed by design, characterization and process control. (b) VIN > 16V to fully enhance output transistor. Otherwise out current must be derated - see graphs. Operation at low supply may cause excessive heating due to increased on-resistance. Tested at 7V guaranteed for 6V by design. (c) Static current of device is approximately 700 mA, see Graph, Page 17 (d) 100% brightness corresponds to VADJ = VADJ(nom) = VREF. Driving the ADJ pin above VREF will increase the VSENSE. Threshold and output current proportionally GS60100 3 TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn Electrical Characteristics (Test conditions: VIN = 24V, Tamb = 25°C, unless otherwise specified.)(a) (cont.) Symbol Parameter Condition Min. Typ. Max. Unit VADJon DC voltage on ADJ pin to switch device from quiescent (off) state to active (on) state VADJ rising 0.2 0.25 0.3 V RADJ Resistance between ADJ pin and VREF 0< VADJ< VREF VADJ>VREF +100mV 30 10.4 50 14.2 65 18 kΩ ILXmean Continuous LX switch current 1 A RLX LX switch ‘On’ resistance @ ILX = 1A 0.5 0.75 Ω ILX(leak) LX switch leakage current 5 µA DPWM(LF) Duty cycle range of PWM signal applied to ADJ pin during low frequency PWM dimming mode PWM frequency <300Hz PWM amplitude = VREF Measured on ADJ pin 0.001 1 Brightness control range 1000:1 DCADJ(*) DC Brightness control range See note (*) 5:1 TSS Soft start time Time taken for output current to reach 90% of final value after voltage on ADJ pin has risen above 0.3V. Requires external capacitor 22nF. See graphs for more details 2 ms fLX Operating frequency (See graphs for more details) ADJ pin floating L=68mH (0.2V) IOUT=1A @ VLED=3.6V Driving 3 LEDs 260 kHz TONmin Minimum switch ‘ON’ time LX switch ‘ON’ 130 (†) ns TOFFmin Minimum switch ‘OFF’ time LX switch ‘OFF’ 70 (†) ns TPWmin_REC Recommended minimum switch pulse width LX switch ‘ON’ or ‘OFF’ 800 ns fLXmax Recommended maximum operating frequency 500 kHz DLX Recommended duty cycle range of output switch at fLXmax 0.3 0.7 Notes: (*) Ratio of maximum brightness to minimum brightness before shutdown VREF = 1.25/0.3. VREF externally driven to 2.5V, ratio 10:1. (†) Parameters are not tested at production. Parameters are guaranteed by design, characterization and process control. GS60100 4 TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn Device Description The device, in conjunction with the coil (L1) and current sense resistor (RS), forms a self-oscillating continuous-mode buck converter. Device operation (refer to Figure 1 - Block diagram and Figure 2 Operating waveforms) Operation can be best understood by assuming that the ADJ pin of the device is unconnected and the voltage on this pin (VADJ) appears directly at the (+) input of the comparator. When input voltage VIN is first applied, the initial current in L1 and RS is zero and there is no output from the current sense circuit. Under this condition, the (-) input to the comparator is at ground and its output is high. This turns MN on and switches the LX pin low, causing current to flow from VIN to ground, via RS, L1 and the LED(s). The current rises at a rate determined by VIN and L1 to produce a voltage ramp (VSENSE) across RS. The supply referred voltage VSENSE is forced across internal resistor R1 by the current sense circuit and produces a proportional current in internal resistors R2 and R3. This produces a ground referred rising voltage at the (-) input of the comparator. When this reaches the threshold voltage (VADJ), the comparator output switches low and MN turns off. The comparator output also drives another NMOS switch, which bypasses internal resistor R3 to provide a controlled amount of hysteresis. The hysteresis is set by R3 to be nominally 15% of VADJ. When MN is off, the current in L1 continues to flow via D1 and the LED(s) back to VIN. The current decays at a rate determined by the LED(s) and diode forward voltages to produce a falling voltage at the input of the comparator. When this voltage returns to VADJ, the comparator output switches high again. This cycle of events repeats, with the comparator input ramping between limits of VADJ ± 15%. Switching thresholds With VADJ = VREF, the ratios of R1, R2 and R3 define an average VSENSE switching threshold of 200mV (measured on the ISENSE pin with respect to VIN). The average output current IOUTnom is then defined by this voltage and RS according to: IOUTnom = 200mV/RS Nominal ripple current is ±30mV/RS Adjusting output current The device contains a low pass filter between the ADJ pin and the threshold comparator and an internal current limiting resistor (50kΩ nom) between ADJ and the internal reference voltage. This allows the ADJ pin to be overdriven with either DC or pulse signals to change the VSENSE switching threshold and adjust the output current. Details of the different modes of adjusting output current are given in the applications section. Output shutdown The output of the low pass filter drives the shutdown circuit. When the input voltage to this circuit falls below the threshold (0.2V nom.), the internal regulator and the output switch are turned off. The voltage reference remains powered during shutdown to provide the bias current for the shutdown circuit. Quiescent supply current during shutdown is nominally 60μA and switch leakage is below 5μA. GS60100 5 TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn Application Information Setting nominal average output current with external resistor RS The nominal average output current in the LED(s) is determined by the value of the external current sense resistor (RS) connected between VIN and ISENSE and is given by: IOUTnom = 0.2/RS [for RS ≥ 0.2V] The table below gives values of nominal average output current for several preferred values of current setting resistor (RS) in the typical application circuit shown on page 1: RS (V) Nominal average output current (mA) 0.20 1000 0.27 740 0.56 357 The above values assume that the ADJ pin is floating and at a nominal voltage of VREF (=1.25V). Note that RS = 0.2V is the minimum allowed value of sense resistor under these conditions to maintain switch current below the specified maximum value. It is possible to use different values of RS if the ADJ pin is driven from an external voltage. (See next section). Output current adjustment by external DC control voltage The ADJ pin can be driven by an external dc voltage (VADJ), as shown, to adjust the output current to a value above or below the nominal average value defined by RS. The nominal average output current in this case is given by: IOUTdc = (VADJ /1.25) x (0.2/RS) [for 0.3< VADJ <2.5V] Note that 100% brightness setting corresponds to VADJ = VREF. When driving the ADJ pin above 1.25V, RS must be increased in proportion to prevent IOUTdc exceeding 1A maximum. The input impedance of the ADJ pin is 50kΩ ±25% for voltages below VREF and 14.2kΩ ±25% for voltages above VREF +100mV. GND GS60100ADJ GND + DC GS60100 6 TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn Output current adjustment by PWM control Directly driving ADJ input A Pulse Width Modulated (PWM) signal with duty cycle DPWM can be applied to the ADJ pin, as shown below, to adjust the output current to a value above or below the nominal average value set by resistor RS: Driving the ADJ input via open collector transistor The recommended method of driving the ADJ pin and controlling the amplitude of the PWM waveform is to use a small NPN switching transistor as shown below: This scheme uses the 50k resistor between the ADJ pin and the internal voltage reference as a pull-up resistor for the external transistor. Driving the ADJ input from a microcontroller Another possibility is to drive the device from the open drain output of a microcontroller. The diagram below shows one method of doing this: If the NMOS transistor within the microcontroller has high Gate / Drain capacitance, this arrangement can inject a negative spike into ADJ input of the GS60100 and cause erratic operation but the addition of a Schottky clamp diode (eg Diodes Inc. SD103CWS) to ground and inclusion of a series resistor (3.3k) will prevent this. See the section on PWM dimming for more details of the various modes of control using high frequency and low frequency PWM signals. PWM GND 0V VADJ GND GS60100 ADJ PWM GND ADJ GND GND ADJ MCU 3.3k GS60100 GS60100 GS60100 7 TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn 8 Package Information (SOP8-EP) TEL:0755-27668758/29126058 web:http://www.zgsemi.com www.086ic.cn GS60100