TS1935B

Preliminary TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter SOT-25 Pin Definition: 1. SW 2. Ground 3. FB 4. EN 5. Input General Description The TS1935B is a current mode step up converter intended for small, low power applications. The converter input voltage ranging from 2.6V to 5.5V. The Output voltage can be set up to 27V. The frequency is 1.2MHz allows the use of small external inductors and capacitors and provides fast transient response. Internal soft start results in small inrush current and extends battery life. Internal power MOSFET with very low RDS (ON) provides high efficiency. The TS1935B automatically transits from PWM to PFM during light load condition further increasing efficiency. The converter also provides protection functions such as under-voltage lockout, current limit and thermal shutdown. Features ● ● ● ● ● ● ● 2.6V to 5.5 V operating input voltage range Adjustable output voltage range up to 27V 1.2MHz Fixed Switching Frequency Internal soft-start function Current limit and Thermal shutdown protection Under voltage Lockout ≤ 1µA Shutdown Current Application ● ● ● ● ● W hite LED Current Source Digital Still Cameras Portable Electronics PDA’s and Palm-Top Computers Local Boost Regulator Ordering Information Part No. TS1935BCX5 RFG Package SOT-25 Packing 3Kpcs / 7” Reel Note: “G” denotes for Halogen Free Absolute Maximum Rating Parameter Input Voltage EN, VFB Voltage SW Voltage Ambient Temperature Range Junction Temperature Range Symbol VIN VEN, VFB VSW TA TJ Limit GND - 0.3 to GND + 6.5 GND - 0.3 to VCC + 0.3 30 -40 to +85 -40 to +125 Unit V V V o o o C C C Storage Temperature Range TSTG -40 to +150 Note: Stress above the listed absolute maximum rating may cause permanent damage to the device Thermal Information Parameter Thermal Resistance* (Junction to Case) Thermal Resistance* (Junction to Ambient) Internal Power Dissipation Maximum Junction Temperature o Symbol ӨJC ӨJA PD Tj Maximum 110 250 (TJ-TA)/ӨJA 150 5 Unit o o C/W C/W o mW C S Lead Solder Temperature (260 C) Note: ӨJA is measured with the PCB copper area of approximately 1 in2(Multi-layer). 1/6 Version: Preliminary Preliminary TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter Electrical Specifications (Ta = 25oC, VIN=5V, EN=VIN, IL=0A unless otherwise noted) Characteristics Input Voltage range Under Voltage Lockout UVLO Hysteresis Step-Up Voltage Adjust Range Operating quiescent current Shutdown current Feedback Voltage FB Input Leakage Current Line Regulation Load Regulation Switching frequency Maximum Duty N-channel MOSFET current limit MOSFET on-resistance (Note 1) SW Leakage Current EN high-level input voltage EN low-level input voltage EN Hysteresis EN input leakage current Thermal Shutdown Thermal Shutdown Hysteresis Note 1: Guaranteed by design FOSC DMAX ILIM RDS(on) ISWL VIH VIL hys IEN-LKG TDS TSH VEN=GND or VCC Duty=50% VCC=3V, ISW =1A VCC=5V, ISW =1A VLX = 27V, VFB =1.5V VOUT ICCQ ISD VFB IFB-LKG VFB = 1.3V VIN = 2.5 to 5.5V IOUT = 20mA VIN = 5V IOUT = 1mA to 400mA IOUT= 0mA, VFB =1.5V VEN=0V Symbol VCC UVLO Rising Conditions Min 2.6 --3 --1.213 -100 -900 82 ----1.0 ------ Typ -2.35 -130 -150 0.1 1.238 0.01 0.2 0.2 1200 87 1.9 650 500 ---200 0.01 150 35 Max 5.5 2.60 -27 250 1 1.263 +100 --1500 --1 -0.4 0.1 --- Units V V mV V µA µA V nA % % KHz % A m µA V V mV µA ° C Pin Description Pin Number 1 2 3 Pin Name SW GND FB Description Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and 27V. Ground. Tie directly to ground plan. Feedback Input. FB voltage is 1.238V. Connect a resistor divider to FB. Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns it off. When not used, connect EN to the input source for automatic startup. The EN pin cannot be left floating. Input Supply Pin. Must be locally bypassed. 4 EN 5 VCC 2/6 Version: Preliminary Preliminary TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter Block Diagram VCC EN Thermal Shutdown Soft Start Vref 1.238V FB UVLO Enable/ Disable Summing Comparator SW Control and Driver Logic Error Amplifier N-MOS Oscillator 1.2MHz GND Slope Compensation Current Sense Application Circuit VIN=5V L1 4.7uH U1 5 VCC 4 EN GND 2 D1 B240A VOUT=12V R4 1M ON C1 10uF OFF C3 1nF TS1935B AX5511 SW FB 1 3 R3 R2 470K C2 R1 54K 4.7uF R2 VOUT = 1.238V X (1 + ------- ) R1 R2 Suggest 390K~820K VIN 2.6~3.6V 2.6~5.3V 2.6~5.5V VOUT 5V 7V 7.5~27V R3 120K 82K 0 3/6 Version: Preliminary Preliminary TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter Application Information Setting the Output Voltage Application circuit item shows the basic application circuit with AX5511 adjustable output version. The external resistor sets the output voltage according to the following equation: R2 VOUT = 1.238V × (1+ ) R1 For most applications, R2 is a suggested a value by 390K~820K . Place the resistor-divider as close to the IC as possible to reduce the noise sensitivity. Under Voltage Lockout (UVLO) To avoid mis-operation of the device at low input voltages an under voltage lockout is included that disables the device, if the input voltage falls below (2.35V-130mV). Input Capacitor Selection The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 10µF ceramic capacitor for most applications is sufficient. For a lower output power requirement application, this value can be decreased. Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current. A 4.7uF ceramic capacitors works for most of the applications. Higher capacitor values can be used to improve the load transient response. Layout Guide 4/6 Version: Preliminary Preliminary TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter SOT-25 Mechanical Drawing DIM A+A1 B C D E E H L Ө1 S1 SOT-25 DIMENSION MILLIMETERS INCHES MIN MAX MIN MAX. 0.09 1.25 0.0354 0.0492 0.30 0.50 0.0118 0.0197 0.09 0.25 0.0035 0.0098 2.70 3.10 0.1063 0.1220 1.40 1.80 0.0551 0.0709 1.90 BSC 0.0748 BSC 2.40 3.00 0.09449 0.1181 0.35 BSC 0.0138 BSC 0º 10º 0º 10º 0.95 BSC 0.0374 BSC 5/6 Version: Preliminary Preliminary TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter Notice Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies. Information contained herein is intended to provide a product description only. No license, express or implied, to any intellectual property rights is granted by this document. Except as provided in TSC’s terms and conditions of sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right. The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications. Customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify TSC for any damages resulting from such improper use or sale. 6/6 Version: Preliminary