AAT4285 ANALOGICTECH | Alldatasheet

Document overview

  • Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
  • PDF pages: 11

Technical content

Features

  • V IN Range: 3.0V to 13.2V
  • Low R DS(ON) — 240m Ω typical @ 12V — 310m Ω Typical at 5V
  • 100µs Slew Rate Turn-on Time
  • Fast Shutdown Load Discharge
  • Low Quiescent Current — Typically 25µA — 1µA Maximum in Shutdown
  • TTL/CMOS Input Logic Level
  • Temperature Range: -40°C to +85°C
  • 8-pin SC70JW Package

Applications

  • 2 Cell Lithium-Ion Batteries
  • Camcorders
  • Handheld Test Equipment
  • Load Switching AAT4285 12V Slew Rate Controlled Load Switch Typical Application AAT4285 COUT 0.1µF CIN 1µF OUTIN GND × 4 VOUT GNDGND VIN ON/OFF IN ON 4285.2007.04.1.0 1

(Top View) Pin # Symbol Function 1,2 IN P-channel MOSFET source. Bypass to ground through a 1µF capacitor. 3 OUT P-channel MOSFET drain connection. Bypass to ground through a 0.1µF capacitor. 4 ON/OFF Active high enable input. A logic low turns the switch off and the device consumes less than 1µA of current. Logic high resumes normal operation. 5, 6, 7, 8 GND Ground connection IN OUT ON/OFF GND GND GND GND IN 1 AAT4285 12V Slew Rate Controlled Load Switch 2 4285.2007.04.1.0

Symbol Description Value Units VIN IN to GND -0.3 to 14 V VON ON/OFF to GND -0.3 to 14 V VOUT OUT to GND -0.3 to V IN + 0.3 V IMAX Maximum Continuous Switch Current 1.7 A IDM Maximum Pulsed Current 3.4 A TJ Operating Junction Temperature Range -40 to 150 °C Symbol Description Value Units θJA Thermal Resistance 140 °C/W PD Maximum Power Dissipation 714 mW AAT4285 12V Slew Rate Controlled Load Switch 4285.2007.04.1.0 3 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at condi- tions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board.

12V Slew Rate Controlled Load Switch 4 4285.2007.04.1.0 Electrical Characteristics1 VIN = 12V, TA = -40°C to +85°C, unless otherwise noted. Typical values are T A = 25°C. Symbol Description Conditions Min Typ Max Units VIN Operation Voltage 3.0 13.2 V VUVLO Under-Voltage Lockout 2.7 3.0 V VUVLO(hys) Under-Voltage Lockout Hysteresis 250 V IQ Quiescent Current ON/OFF = Active, IOUT = 0 25 50 µA IQ(OFF) Off Supply Current ON/OFF = Inactive, OUT = Open 1.0 µA ISHD Off Switch Current ON/OFF = GND, VOUT = 0 0.1 1.0 µA VIN = 12V 240 400 RDS(ON) On Resistance V IN = 5V 310 500 m Ω VIN = 3.3V 380 TCRRDS On Resistance Temperature 2800 ppm/°CCoefficient TD(ON) Output Turn-On Delay Time2 RLOAD = 20Ω, TA = 25°C 20 40 µs TON Turn-On Rise Time2 RLOAD = 20Ω, TA = 25°C 100 250 µs TD(OFF) Output Turn-Off Delay Time2 RLOAD = 20Ω, TA = 25°C 1 10 µs RPD Output Pull-Down Resistance ON/OFF Inactive, TA = 25°C 520 800 ΩDuring OFF VON(L) ON/OFF Input Logic Low Voltage V IN = 3V to 13V 0.4 V VON(H) ON/OFF Input Logic High Voltage V IN = 3V to 13V 1.6 V ION ON/OFF Leakage Current V ON/OFF = 13V -1.0 1.0 µA 1. The AAT4285 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assu red by design, characterization, and correlation with statistical process controls. 2. Contact factory for other turn-on and delay options.

ON/OFF Threshold High vs. Input Voltage Input Voltage (V) ON/OFF Threshold (V) 0.65 0.70 0.750.80 0.85 0.900.951.001.05 3579 1 1 1 -40°C 25°C 85°C ON/OFF Threshold Low vs. Input Voltage Input Voltage (V) ON/OFF Threshold (V) 0.55 0.60 0.65 0.70 0.75 0.800.850.900.95 3579 1 1 1 3 -40°C 25°C 85°C RDS(ON) vs. Input Voltage Input Voltage (V) RDS(ON) (mΩΩ) 220 260 300 340 380420 3 4 5 6 7 8 9 10 11 12 0.5A 0.1A RDS(ON) vs. Temperature Temperature (°°C) RDS(ON) (mΩ) 100 150 200 250 300 350 400 450 500 -40 -15 10 35 60 85 VIN = 3.3V VIN = 4.2V VIN = 12VVIN = 5V Quiescent Current vs. Input Voltage Input Voltage (V) Quiescent Current (µA) 1015 253035 02468 1 0 1 2 1 4 Quiescent Current vs. Temperature Temperature (°°C) Quiescent Current (µA) -40 -15 10 35 60 85 VIN = 12V VIN = 5V VIN = 4.2V VIN = 3.3V AAT4285 12V Slew Rate Controlled Load Switch 4285.2007.04.1.0 5

12V Slew Rate Controlled Load Switch 6 4285.2007.04.1.0 Typical Characteristics Turn-On (VIN = 12V; 600mA Load) Time (25µs/div) ON/OFF (5V/div) VOUT (5V/div) IOUT (500mA/div) Output Pull-Down Resistance vs. Temperature Temperature (°°C) Resistance (Ω) 400 450500 550 600 650700750800 -40 -15 10 35 60 85 VIN = 3.3V VIN = 12VVIN = 5V VIN = 4.2V Turn-Off (VIN = 12V; 600mA Load) Time (10µs/div) ON/OFF (5V/div) VOUT (5V/div) IOUT (500mA/div)

12V Slew Rate Controlled Load Switch 4285.2007.04.1.0 7 Functional Description The AAT4285 is a slew rate controlled P-channel MOSFET power switch designed for high-side load switching applications. The device operates with input voltages ranging from 3.0V to 13.2V, making it ideal for single- or multi-cell battery-powered applications. In cases where the input voltage drops below 3.0V, the AAT4285 MOSFET is pro- tected from entering the saturated region of opera- tion by automatically shutting down. In addition, the TTL compatible ON/OFF pin makes the AAT4285 an ideal level-shifted load switch. The slew rate controlling feature eliminates inrush current when the MOSFET is turned on, allowing the AAT4285 to operate with a small input capacitor, or no input capacitor at all. During slewing, the current ramps linearly until it reaches the level required for the output load condition. The proprietary control method works by careful control and monitoring of the MOSFET gate voltage. When the device is switched ON, the gate voltage is quickly increased to the threshold level of the MOSFET. Once at this level, the current begins to slew as the gate voltage is slowly increased until the MOSFET becomes fully enhanced. Once it has reached this point, the gate is quickly increased to the full input voltage and R DS(ON) is minimized.

12V Slew Rate Controlled Load Switch 8 4285.2007.04.1.0 Applications Information Input Capacitor A 1µF or larger capacitor is typically recommended for CIN in most applications. A C IN capacitor is not required for basic operation. However, CIN is useful in preventing load transients from affecting upstream circuits. C IN should be located as close to the device VIN pin as practically possible. Ceramic, tantalum, or aluminum electrolytic capac- itors may be selected for C IN. There is no specific capacitor ESR requirement for C IN. However, for higher current operation, ceramic capacitors are recommended for C IN due to their inherent capabil- ity over tantalum capacitors to withstand input cur- rent surges from low impedance sources, such as batteries in portable devices. Output Capacitor For proper slew operation, a 0.1µF capacitor or greater between OUT and GND is recommended. The output capacitor has no specific capacitor type or ESR requirement. If desired, C OUT may be increased without limit to accommodate any load transient condition without adversely affecting the device turn-on slew rate time. Enable Function The AAT4285 features an enable / disable function. This pin (ON/OFF ) is compatible with both TTL and CMOS logic. Reverse Output-to-Input Voltage Conditions and Protection Under normal operating conditions, a parasitic diode exists between the output and input of the load switch. The input voltage should always remain greater than the output load voltage, maintaining a reverse bias on the internal parasitic diode. Conditions where V OUT might exceed VIN should be avoided since this would forward bias the internal parasitic diode and allow excessive current flow into the OUT pin and possibly damage the load switch. In applications where there is a possibility of V OUT exceeding VIN for brief periods of time during nor- mal operation, the use of a larger value CIN capac- itor is highly recommended. A larger value of C IN with respect to C OUT will affect a slower C IN decay rate during shutdown, thus preventing V OUT from exceeding V IN. In applications where there is a greater danger of VOUT exceeding VIN for extended periods of time, it is recommended to place a Schottky diode from IN to OUT (connecting the cathode to IN and anode to OUT). The Schottky diode forward voltage should be less than 0.45V. Thermal Considerations and High Output Current Applications The AAT4285 is designed to deliver a continuous output load current. The limiting characteristic for maximum safe operating output load current is package power dissipation. In order to obtain high operating currents, careful device layout and circuit operating conditions need to be taken into account. The following discussions will assume the load switch is mounted on a printed circuit board utilizing the minimum recommended footprint, as stated in the Layout Considerations section of this datasheet. At any given ambient temperature (T A), the maxi- mum package power dissipation can be deter- mined by the following equation: Constants for the AAT4285 are maximum junction temperature, T J(MAX) = 125°C, and package thermal resistance, θJA = 140°C/W. Worst case conditions are calculated at the maximum operating tempera- ture where T A = 85°C. Typical conditions are calcu- lated under normal ambient conditions where T A = 25°C. At T A = 85°C, P D(MAX) = 286mW. At T A = 25°C, PD(MAX) = 714mW. The maximum continuous output current for the AAT4285 is a function of the package power dissipa- tion and the R DS of the MOSFET at TJ(MAX). The max- imum RDS of the MOSFET at TJ(MAX) is calculated by increasing the maximum room temperature RDS by the R DS temperature coefficient. The temperature coefficient (TCRRDS) is 2800ppm/°C. Therefore, MAX RDS125°C = RDS25°C · (1 + TCRRDS · ΔT) MAX RDS125°C = 240mΩ · (1 + 0.0028 · (125°C - 25°C)) = 307mΩ PD(MAX) = TJ(MAX) - TA θJA

For maximum current, refer to the following equation: For example, if V IN = 12V, RDS(MAX) = 307mΩ and TA = 25°C, IOUT(MAX) = 1.53A. If the output load cur- rent were to exceed 1.53A or if the ambient tem- perature were to increase, the internal die temper- ature would increase, and the device would be damaged. Higher peak currents can be obtained with the AAT4285. To accomplish this, the device thermal resistance must be reduced by increasing the heat sink area or by operating the load switch in a duty cycled manner. High Peak Output Current Applications Some applications require the load switch to operate at a continuous nominal current level with short duration, high-current peaks. The duty cycle for both output current levels must be taken into account. To do so, first calculate the power dissipation at the nominal continuous current level, and then add in the additional power dissipation due to the short duration, high-current peak scaled by the duty factor. For example, a 12V system using an AAT4285 operates at a continuous 100mA load current level and has short 2A current peaks. The current peak occurs for 500µs out of a 5ms period. First, the current duty cycle is calculated: The load current is 100mA for 90% of the 5ms peri- od and 2A for 10% of the period. De-rated for temperature: The power dissipation for a 100mA load is calculat- ed as follows: The power dissipation for 100mA load at 90% duty cycle is 2.76mW. Now the power dissipation for the remaining 10% of the duty cycle at 2A is calculated: The power dissipation for 2A load at 10% duty cycle is 123mW. Finally, the two power figures are summed to determine the total true power dissipa- tion under the varied load. The maximum power dissipation for the AAT4285 operating at an ambient temperature of 85°C is 286mW. The device in this example will have a total power dissipation of 123mW. This is well within the thermal limits for safe operation of the device; in fact, at 85°C, the AAT4285 will handle a 2A pulse for up to 23% duty cycle. At lower ambient temperatures, the duty cycle can be further increased. Printed Circuit Board Layout Recommendations For proper thermal management and to take advantage of the low RDS(ON) of the AAT4285, a few circuit board layout rules should be followed: V IN PD(TOTAL) = PD(100mA) + PD(2A) PD(TOTAL) = 2.76mW + 123mW PD(TOTAL) = 125.76mW PD(MAX) = IOUT 2 · RDS PD(2A) = (2A)2 · 307mΩ PD(2A) = 1.23W PD(10%D/C) = %DC · PD(2A) PD(10%D/C) = 123mW % Peak Duty Cycle = % Peak Duty Cycle = x 100 ⎝⎠ = 10% 500μs 5.0ms PD(MAX) = IOUT 2 · RDS PD(100mA) = (100mA)2 · 307mΩ PD(100mA) = 3.07mW PD(90%D/C) = %DC · PD(100mA) PD(90%D/C) = 2.76mW IOUT(MAX) < PD(MAX) RDS AAT4285 12V Slew Rate Controlled Load Switch 4285.2007.04.1.0 9

12V Slew Rate Controlled Load Switch 4285.2007.04.1.0 11

Ordering Information

Package Information

All dimensions in millimeters. 0.225 ± 0.075 0.45 ± 0.10 0.05 ± 0.05 2.10 ± 0.30 2.00 ± 0.20 7° ± 3° 4° ± 4° 0.15 ± 0.05

1.10 MAX

0.100 2.20 ± 0.20 0.048REF 0.50 BSC 0.50 BSC 0.50 BSC All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means Package Marking 1 Part Number (Tape and Reel)2 SC70JW-8 UAXYY AAT4285IJS-3-T1 Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech pr oduct. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service with- out notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, an d AnalogicTech disclaims any express or implied war- ranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a part icular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent An alogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holder s. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.