M7085

M7085 UTC | Alldatasheet

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UNISONIC TECHNOLOGIES CO., LTD M7085 CMOS IC w w w . u n i s o n i c . c o m . t w 1 of 8 Copyright © 2005 Unisonic Technologies Co., Ltd QW-R502-092,A PFM STEP-DOWN DC-DC CONTROLLER „ DESCRIPTION The UTC M7085 step-down DC-DC Controller is optimized for use with a power PMOSFET. It utilize a Pulse-Frequency Modulation (PFM) control scheme that implies high efficiency operation at light loads. There are two user-selectable over-current protection methods one provides over-current protec tion by taking advantage of the R DS(ON) of the P- Channel. The other provides accurate over-current protection with the use of an external sense resistor. The cycle-by-cycle current limit threshold can be adjusted with a external resistor. „ FEATURES * High efficiency 90% and up is possible * Low dropout operationğ100% duty cycle * Maximum operating frequency > 1MHz * Two methods of over-current protection * 4.5V ~ 35V wide input range * 1.24V ~ V IN adjustable output range MSOP-8 *Pb-free plating product number: M7085L „ ORDERING INFORMATION Order Number Normal Lead Free Plating Package Packing M7085-SM1-R M7085L-SM1-R MSOP-8 Tape Reel M7085-SM1-T M7085L-SM1-T MSOP-8 Tube M7085 L-SM1-R (1)Packing Type (2)Package Type (3)Lead Plating (1) R: Tape Reel, T: Tube (2) SM1: MSOP-8 (3) L: Lead Free Plating , Blank: Pb/Sn

UNISONIC TECHNOLOGIES CO., LTD 2 of 8 www.unisonic.com.tw QW-R502-092,A „ PIN CONFIGURATION SGND ISENSE NC FB ADJ PGND PGATE VIN1 „ PIN DESCRIPTION PIN NO PIN NAME DESCRIPTION

1 I SENSE The over-current protection input pin that be connected to Drain node of the external P-

Channel. 2 SGND Signal ground. 3 NC No connection. 4 FB The feedback voltage input. 5 ADJ The over-current protection input pi n that adjust current limit threshold. 6 PGND Power ground. 7 GATE Driver pin to Gate of the external P-Channel. PGATE swings between V IN and VIN-5V.

8 V IN Power supply

UNISONIC TECHNOLOGIES CO., LTD 3 of 8 www.unisonic.com.tw QW-R502-092,A „ BLOCK DIAGRAM ADJ ISENSE 5.5µA OC CMP Internal Regulator One shot pulse Generator Band Gap 1.240V CMP PMOS BUFFER VIN PGATE PGND FB SGND 1.240V Internal 6V

UNISONIC TECHNOLOGIES CO., LTD 4 of 8 www.unisonic.com.tw QW-R502-092,A „ ABSOLUTE MAXIMUM RATING PARAMETER SYMBOL RATINGS UNIT Input Voltage V IN -0.3 ~ 36 V PGATE Voltage V PGATE -0.3 ~ 36 V FB Voltage V FB -0.3 ~ 5 V ISENSE Voltage V ISNS -1.0 ~ 36 V ADJ Voltage V ADJ -0.3 ~ 36 V Power Dissipation (TA =25¥) PD 400 mW Junction Temperature T J 150 Ċ Storage Temperature T STG -65 ~ +150 Ċ Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. „ OPERATING RATINGS PARAMETER SYMBOL RATINGS UNIT Supply Voltage 4.5 ~ 35 V Operating Junction Temperature TOPR -40 ~ +125 Ċ „ ELECTRICAL CHARACTERISTICS VIN = 12V, VISNS = VIN − 1V, and VADJ = VIN − 1.1V, Ta=25Ċ PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Feedback Voltage (Note 1) V FB 1.224 1.215 1.240 1.256 1.265 V Minimum Driver Voltage V PGATE(MIN) VIN = 4.5V VFB = 1.0V IGATE = 100µA sink 1.15 V Comparator Hysteresis V HYS 10 21 mV RADJ = 20Ω 110 Current Limit Comparator Trip Voltage V CL (Note2) RADJ = 160Ω 880 mV Current Limit Comparator Offset V CL(OFF) V FB = 1.5V -20 0 +20 mV Current Limit ADJ Current Source I CL(ADJ) V FB = 1.5V 3.0 5 7.0 µA FB pin Bias Current (Note 3) I FB V FB = 1.0V 320 756 nA Source VIN = 7V, PGATE = 3.5V 0.4 Driver Output Current I PGATE Sink VIN = 7V, PGATE = 3.5V 0.3 A Source ISOURCE = 100mA 5 Driver Resistance R PGATE Sink ISINK = 100mA 8 Ω Current Limit One Shot off Time T CL VADJ = 11.5V VISNS = 11.0V VFB = 1.0V 5 8 13 µS Minimum on Time in Normal Operation T OPR(MIN) VISNS = VADJ+0.1V CLOAD on OUT = 1000Pf (Note 4) 110 ns Minimum on Time in Current Limit T CL(MIN) VISNS = VADJ+0.1V VFB = 1.0V CLOAD on OUT = 1000pF (Note 4) 185 ns Feedback Voltage Line Regulation %V FB/V¶ IN 4.5 ≤ VIN ≤ 35V 0.010 %/V Quiescent Current at Ground Pin I Q FB = 1.5V (Not Switching) 300 500 µA Note 1. The VFB is the trip voltage at the FB pin when PGATE switches from high to low. 2. VCL = ICL_ADJ * RADJ 3. Bias current flows out from the FB pin. 4. A 1000pF capacitor is connected between V IN and PGATE.

UNISONIC TECHNOLOGIES CO., LTD 5 of 8 www.unisonic.com.tw QW-R502-092,A „ TYPICAL APPLICATION CIRCUIT UTC M7085 ADJ ISENSE PGATE VIN FB RADJ CADJ CIN 22µF VIN 4.5V ~ 35V 2.6 COUT 100uF VOUT 3.3V D1 R1 33KȤ 20KȤ 22µH

range of resistor values is acceptable. for a period of 9µs(typical). The current limit is adjusted by an external resistor, RADJ. Where 3.0µA is the minimum ICL(ADJ) value. P-Channel. The inductor current is determined by sensing the VDS. It can be calculated as follows. FIGURE 1. Current Sensing by VDS low duty cycle operation, the maximum operating frequency will be limited by this minimum on time.

the P-Channel, as shown in Figure 2. FIGURE 2. Current Sensing by External Resistor load must be applied after start-up. have little to no effect on soft-start. charge and discharge of the capacitance is less than 10% of the total ripple across the capacitor. higher reverse voltage rating to achieve acceptable performance.

UNISONIC TECHNOLOGIES CO., LTD 8 of 8 www.unisonic.com.tw QW-R502-092,A „ APPLICATION INFORMATION(Cont.) P-Channel MOSFET Selection(Q1) An external P-Channel power MOSFET must be used the UTC M7085 key selection criteria for the power for the P-Channel are the maximum Drain-Source voltage (V DS) MOSFET are the gate threshold, V GS, the “ON” resistance, RDS(ON) and its total gate charge. The voltage across the PFET when it is turned off is equal to the sum of the input voltage and the diode forward voltage. The VDS must be selected to provide some margin beyond the input voltage. RDS(ON)determines the conduction losses for each switching cy cle, the lower the ON resistance, the higher the efficiency can be chivied. A power MOSFET with lower gate charge can give lowe r switching losses but the fast transient can cause unwanted EMI to the system. Compromise in between is required during the des ign stage. keeping the gate capacitance below 2000pF is recommended. UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.