A6902D13TR

A6902D Up to 1 A step down switching regulator with adjustable current limit for automotive applications Features ■ Qualified following the AEC-Q100 requirements (temperature grade 3), see PPAP for more details. Up to 1 A DC output current Operating input voltage from 8 V to 36 V Output voltage adjustable from 1.235 V to 35 V Precise 3.3 V (±2 %) reference voltage 250 kHz Internally fixed frequency Voltage feedforward Zero load current operation Internal current limiting Protection against feedback disconnection Thermal shutdown SO-8 ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Applications ■ ■ ■ Automotive applications Adjustable current generator Simple step-down converters with adjustable current limit Figure 1. Application schematic VCC VREF OUT L1 22µH D1 Rsense 100mO R1 R1 5.6kO C4 100µF 10V R3 5.1kO GND R2 3.3kO VOUT=3.3V VIN=8V to 36V VIN=8V to 36V C1 10µF 35V C3 220pF C2 22nF COMP L6902D CS+ CSFB STPS340U August 2008 Rev 4 1/12 www.st.com 1 A6902D Contents 1 2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 2.2 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1 3.2 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 5 6 7 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2/12 Description A6902D 1 Description The A6902D is a complete and simple step down switching regulator with adjustable current limit. Based on a voltage mode structure it integrates a current error amplifier to have a constant voltage and constant current control. By means of an on board current sense resistor and the availability of the current sense pins (both compatible to Vcc and for Cscompatible with GND too) a current limit programming is very simple and accurate. Moreover constant current control can be used to charge NiMH and NiCd batteries.The device can be used as a standard DC/DC converter with adjustable current limit (set by using the external sense resistor). The internal robust P-channel DMOS transistor with a typical of 250 mΩ assures high efficiency and a minimum dropout even at high output current level. The internal limiting current (latched function) of typical value of 2.5 A protects the device from accidental output short circuit avoiding dangerous loads damage. If the temperature of the chip goes higher than a fixed internal threshold (150 °C with 20 °C hysteresis), the power stage is turned off. Other protections beside thermal shutdown complete the device for a safe and reliable application: overvoltage protection, frequency folback overcurrent protection and protection vs. feedback disconnection. The internal fixed switching frequency of 250 kHz, and the SO-8 package pin allow to built an ultra compact DC/ DC converter with a minimum board space. 3/12 A6902D 2 2.1 Pin connection Pin connection Figure 2. Pin connection (top view) 2.2 Pin description Table 1. N 1 2 3 4 5 6 7 8 Pin description Pin OUT CS+ CSCOMP FB VREF GND VCC Regulator output. Current error amplifier input (current sense at higher voltage) Current error amplifier input (current sense at lower voltage) E/A output for frequency compensation. Feedback input. Connecting directly to this pin results in an output voltage of 1.23 V. An extenal resistive divider is required for higher output voltages. 3.3 V reference voltage. No cap is need for stability. Ground. Unregulated DC input voltage. Description 4/12 Electrical data A6902D 3 3.1 Electrical data Maximum ratings Table 2. Symbol V8 V1 I1 V4 , V5 V2, V3 PTOT TJ TSTG Input voltage OUT pin DC voltage OUT pin peak voltage at Δt = 0.1μs Maximum output current Analog pins Analog pins Power dissipation at TA ≤ 70 °C Operating junction temperature range Storage temperature range Absolute maximum ratings Parameter Value 40 -1 to 40 -5 to 40 int. limit. 4 -0.3 to VCC 0.7 -40 to 150 -55 to 150 V V W °C °C Unit V V V 3.2 Thermal data Table 3. Symbol RthJA Thermal data Parameter Maximum thermal resistance junction-ambient SO8 110 (1) Unit °C/W 1. Package mounted on board 5/12 A6902D 4 Electrical characteristics Table 4. Symbol VCC RDS(on) IL fSW Electrical characteristics (TJ = -40 to 125 °C, VCC = 12 V, unless otherwise specified) Parameter Operating input voltage range MOSFET on resistance Maximum limiting current (1) Switching frequency Duty cycle VCC = 8.5 V VCC = 8.5 V, TJ = 25 °C 1.8 2 212 0 Test conditions V0 = 1.235 V; I0 = 2 A Min 8 0.250 2.5 2.5 250 Typ Max 36 0.5 3.2 A 3.2 280 100 kHz % Unit V Ω Dynamic characteristics (see test circuit). V5 η Voltage feedback Efficiency 8 V < VCC < 36 V, 20 mA < I0 < 1 A V0 = 5 V, VCC = 12 V 1.198 1.235 90 1.272 V % DC characteristics Iqop Iq Total operating quiescent current Quiescent current Duty cycle=0; VFB=1.5 V 3 5 2.7 mA mA Error amplifier VOH VOL Io source Io sink Ib High level output voltage Low level output voltage Source output current Sink output current Source bias current DC open loop gain gm VOFFS ICS+ ICSTransconductance Input offset voltage CS+ output current CS- output current RL= 50 8 VFB=1 V VFB=1.5 V VCOMP = 1.9 V; VFB = 1 V VCOMP = 1.9 V; VFB = 1.5 V 160 1 300 1.5 2.5 58 2.3 90 100 1.5 1.5 110 3 3 4 3.6 0.4 V V μA mA μA dB mS mV μA μA ICOMP = -0.1 mA to 0.1 mA; VCOMP = 1.9 V VCS- = 1.8 V; VCS+ = Vcomp I0 =1 A; RSENSE =100 mΩ; VOUT < VCC-2 V I0 =1A; RSENSE =100 mΩ; VOUT < VCC-2 V 6/12 Electrical characteristics Table 4. Symbol A6902D Electrical characteristics (continued) (TJ = -40 to 125 °C, VCC = 12 V, unless otherwise specified) Parameter Test conditions Min Typ Max Unit Reference section Reference voltage Line regulation Load regulation Short circuit current IREF = 0 to 5 mA VCC = 8 V to 36 V IREF = 0mA VCC = 8 V to 36 V IREF = 0 to 5 mA 5 3.2 3.3 5 8 18 3.399 10 15 35 V mV mV mA 1. With TJ = 85 °C, Ilim_min = 2 A, assured by design, characterization and statistical correlation. 7/12 A6902D 5 Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect . The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com 8/12 Package mechanical data A6902D Table 5. Dim SO-8 mechanical data mm Min Typ Max 1.75 0.25 1.65 0.51 0.25 5.00 4.00 1.27 5.80 0.25 0.40 6.20 0.50 1.27 0.228 0.010 0.016 Min 0.053 0.004 0.043 0.013 0.007 0.189 0.15 0.050 0.244 0.020 0.050 inch Typ Max 0.069 0.010 0.065 0.020 0.010 0.197 0.157 A A1 A2 B C D(1) E e H h L k ddd 1.35 0.10 1.10 0.33 0.19 4.80 3.80 0° (min), 8° (max) 0.10 0.004 1. Dimension D does not include mold flash, protrusions or gate burrs. Mold flash, protrusions or gate burrs shall not exceed 0.15mm (0.006 inch) in total (both side). 9/12 A6902D 6 Order codes Table 6. Order codes Order codes A6902D SO-8 A6902D13TR Tape and reel Package Packaging Tube 10/12 Revision history A6902D 7 Revision history Table 7. Date 02-Oct-2007 5-Nov-2007 2-May-2008 28-Aug-2008 Document revision history Revision 1 2 3 4 Initial release Updated: Table 4 on page 6 Updated: Table 4 on page 6 Updated: Coverpage and Table 4 on page 6 Changes 11/12 A6902D Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. 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