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 Application ● 2.6V to 5.5 V operating input voltage range ● White LED Current Source ● Adjustable output voltage range up to 27V ● Digital Still Cameras ● 1.2MHz Fixed Switching Frequency ● Portable Electronics ● Internal soft-start function ● PDA’s and Palm-Top Computers ● Current limit and Thermal shutdown protection ● Local Boost Regulator ● Under voltage Lockout ● ≤ 1µA Shutdown Current Ordering Information Part No. Package Packing SOT-25 3Kpcs / 7” Reel TS1935BCX5 RFG Note: “G” denotes for Halogen Free Absolute Maximum Rating Parameter Symbol Limit Unit Input Voltage VIN GND - 0.3 to GND + 6.5 V VEN, VFB GND - 0.3 to VCC + 0.3 V VSW 30 EN, VFB Voltage SW Voltage Ambient Temperature Range -40 to +85 -40 to +125 o TA Junction Temperature Range TJ V o C C o Storage Temperature Range TSTG -40 to +150 Note: Stress above the listed absolute maximum rating may cause permanent damage to the device C Thermal Information Parameter Symbol Maximum ӨJC Thermal Resistance* (Junction to Case) 110 o Thermal Resistance* (Junction to Ambient) ӨJA 250 Internal Power Dissipation PD (TJ-TA)/ӨJA Maximum Junction Temperature Tj 150 o Lead Solder Temperature (260 C) Note: ӨJA is measured with the PCB copper area of approximately 1 in2(Multi-layer). 1/8 Unit o 5 C/W C/W mW o C S Version: A12 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 Symbol Conditions VCC Under Voltage Lockout UVLO Rising UVLO Hysteresis Min Typ Max Units 2.6 -- 5.5 V -- 2.35 2.60 V -- -130 -- mV 3 -- 27 V Step-Up Voltage Adjust Range VOUT Operating quiescent current ICCQ IOUT= 0mA, VFB =1.5V -- 150 250 µA Shutdown current ISD VEN=0V -- 0.1 1 µA Feedback Voltage VFB 1.213 1.238 1.263 V -100 0.01 +100 nA -- 0.2 -- % - 0.2 -- % FB Input Leakage Current IFB-LKG VFB = 1.3V VIN = 2.5 to 5.5V IOUT = 20mA VIN = 5V IOUT = 1mA to 400mA Line Regulation Load Regulation Switching frequency FOSC 900 1200 1500 KHz Maximum Duty DMAX 82 87 - % Duty=50% -- 1.9 -- A VCC=3V, ISW =1A -- 650 - VCC=5V, ISW =1A -- 500 -- VLX = 27V, VFB =1.5V -- -- 1 µA N-channel MOSFET current limit ILIM MOSFET on-resistance (Note 1) RDS(on) mΩ SW Leakage Current ISWL EN high-level input voltage VIH 1.0 -- -- V EN low-level input voltage VIL -- -- 0.4 V EN Hysteresis hys -- 200 - mV -- 0.01 0.1 µA EN input leakage current IEN-LKG VEN=GND or VCC Thermal Shutdown TDS -- 150 -- Thermal Shutdown Hysteresis Note 1: Guaranteed by design TSH -- 35 -- °C Pin Description Pin Number Pin Name 1 SW 2 GND 3 FB 4 EN 5 VCC 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. 2/8 Version: A12 TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter Block Diagram EN VCC UVLO Soft Start Thermal Shutdown Enable/ Disable Summing Comparator Vref 1.238V FB SW Control and Driver Logic Error Amplifier N-MOS Oscillator 1.2MHz GND Current Sense Slope Compensation Application Circuit VIN=5V R4 1M ON C1 10uF D1 B240A L1 4.7uH TS1935B AX5511 U1 5 VCC 4 EN SW FB C3 R2 470K 1 3 C2 R3 GND 2 OFF VOUT=12V R1 54K 4.7uF 1nF 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 120KΩ 82KΩ 0Ω 3/8 Version: A12 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~820KΩ. 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 4/8 Version: A12 TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter Electrical Characteristics Curve Figure 1. Quiescent Current vs. Input Voltage Figure 2. Frequency vs. Input Voltage Figure 3. FB Voltage vs. Input Voltage Figure 4. FB Voltage vs. Output Current Figure 5. FB Voltage vs. Temperature Figure 6. Frequency vs. Temperature 5/8 Version: A12 TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter Electrical Characteristics Curve Figure 7. Threshold Voltage vs. Temperature Figure 8. Max. Duty vs. Temperature Figure 9. UVLO vs. Temperature Figure 10. Duty vs. Current Limit Figure 11. Efficiency vs. Output Current Figure 12. Efficiency vs. Output Current 6/8 Version: A12 TS1935B 1.9A / 1.2MHz Boost DC to Dc Converter SOT-25 Mechanical Drawing Unit: Millimeters 7/8 Version: A12 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. 8/8 Version: A12