A5970D Up to 1 A step down switching regulator 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 4 V to 36 V ■ Output voltage adjustable from 1.235 V to 35 V ■ Low dropout operation: 100 % duty cycle ■ 250 kHz Internally fixed frequency ■ Voltage feedforward ■ Zero load current operation ■ Internal current limiting ■ Inhibit for zero current consumption ■ Synchronization ■ Protection against feedback disconnection ■ Thermal shutdown SO-8 Description The A5970D is a step down monolithic power switching regulator capable to deliver up to 1 A at output voltages from 1.2 V to 35 V. The device uses an internal P-channel D-MOS transistor (with a typical RDS(on) of 250 mΩ) as switching element to minimize the size of the external components. An internal oscillator fixes the switching frequency at 250 kHz. Having a minimum input voltage of 4 V only, it is particularly suitable for 5 V bus. Applications ■ Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection. Dedicated to automotive applications Figure 1. Application schematic L1 33uH VIN=4.4V to 35V VCC 8 1 4 2 SYNCH COMP C4 C1 A5970D 22nF 6 35V August 2008 D1 R1 STPS340U 5k6 C2 100uF 10V FB 10uF CERAMIC Vout=3.3V OUT C3 R3 220pF 4k7 VREF 3.3V 5 7 GND 3 INH R2 3k3 Rev 4 1/12 www.st.com 1 Contents A5970D Contents 1 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 Packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2/12 A5970D 1 Pin settings 1.1 Pin connection Figure 1. 1.2 Pin connection (top view) Pin description Table 1. Pin description N Pin Description 1 OUT 2 SYNCH 3 INH 4 COMP 5 FB 6 VREF 3.3 V VREF. No cap is requested for stability. 7 GND Ground. 8 VCC Unregulated DC input voltage. Regulator output. Master/slave synchronization. A logical signal (active high) disables the device. If INH not used the pin must be grounded. When it is open an internal pull-up disable the device. 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. 3/11 Electrical data A5970D 2 Electrical data 2.1 Maximum ratings Table 2. Absolute maximum ratings Symbol Unit 40 V V V Input voltage V1 OUT pin DC voltage OUT pin peak voltage at Δt = 0.1 μs -1 to 40 -5 to 40 I1 Maximum output current int. limit. Analog pins 4 V -0.3 to VCC V -0.3 to 4 V 0.75 W Operating junction temperature range -40 to 150 °C Storage temperature range -55 to 150 °C SO8 Unit 120 (1) °C/W V3 INH V2 SYNCH PTOT Tj TSTG Power dissipation at TA ≤ 70 °C Thermal data Table 3. Thermal data Symbol RthJA Parameter Maximum thermal resistance junction-ambient 1. Package mounted on board 4/11 Value V8 V4 , V5 2.2 Parameter A5970D Electrical characteristics Table 4. Electrical characteristics (TJ = -40 to 125 °C, VCC =12 V, unless otherwise specified) Symbol VCC RDS(on) IL fSW Parameter Operating input voltage range Test condition V0 = 1.235 V; I0 = 1 A Min Maximum limiting current (1) Typ Max Unit 36 V 0.250 0.5 Ω 4 MOSFET on resistance VCC = 5 V 1.35 1.87 2.25 VCC = 5 V, TJ = 25 °C 1.5 1.87 2.25 212 250 280 kHz 100 % 1.272 V Switching frequency Duty cycle A 0 Dynamic characteristics (see test circuit). V5 Voltage feedback 4.4 V < VCC < 36 V, 20 mA < I0 < 2 A η Efficiency V0 = 5 V, VCC = 12 V 1.198 1.235 90 % DC characteristics Iqop Total operating quiescent current Iq Quiescent current Iqst-by Total stand-by quiescent current 3 Duty cycle=0; VFB=1.5 V 5 mA 2.5 mA Vinh > 2.2 V 50 100 μA VCC = 36 V; Vinh > 2.2 V 80 150 μA 0.8 V Inhibit Device ON INH threshold voltage Device OFF 2.2 V 3.5 V Error amplifier VOH High level output voltage VFB = 1 V VOL Low level output voltage VFB = 1.5 V Source output current VCOMP = 1.9 V; VFB = 1 V 190 300 μA Io sink Sink output current VCOMP = 1.9 V; VFB=1.5 V 1 1.5 mA Ib Source bias current Io source DC open loop gain 0.4 2.5 RL= 8 3 50 65 4 V μA dB 5/11 Electrical characteristics Table 4. A5970D Electrical characteristics (continued) (TJ = -40 to 125 °C, VCC =12 V, unless otherwise specified) Symbol gm Parameter Transconductance Test condition Min ICOMP = -0.1 mA to 0.1 mA; VCOMP = 1.9 V Typ Max 2.3 Unit mS Synch function High input voltage VCC= 4.4 to 36 V; Low input voltage VCC= 4.4 to 36 V; (2) 2.5 0.11 0.21 VREF V 0.74 V 0.25 0.45 mA Slave synch current Vsynch= 0.74 V Vsynch= 2.33 V Master output amplitude Isource= 3 mA 2.75 3 V Output pulse width no load, Vsynch= 1.65 V 0.20 0.35 μs Reference voltage IREF = 0 to 5 mA VCC = 4.4 V to 36 V 3.2 3.3 3.399 V Line regulation IREF = 0mA VCC = 4.4 V to 36 V 5 10 mV Load regulation IREF = 0 mA 8 15 mV 18 35 mA Reference section Short circuit current 5 1. With TJ = 85 °C, Ilim_min = 1.5 A, assured by design, characterization and statistical correlation. 2. Guaranteed by design 6/11 A5970D 4 Typical characteristics Figure 2. Junction temperature vs output current Figure 3. Load regulation Figure 4. Junction temperature vs output voltage Figure 5. Line regulation 7/11 Typical characteristics A5970D Figure 6. Junction temperature vs output current Figure 7. Output voltage vs junction temperature Figure 8. Quiescient current vs junction temperature Figure 9. Switching frequency vs junction temperature 8/11 A5970D Figure 10. Shutdown current vs junction temperature Figure 11. Efficiency vs output current Figure 12. Efficiency vs output current 9/11 Package mechanical data 5 A5970D 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 10/11 A5970D Table 5. SO-8 mechanical data mm inch Dim Min Typ Max Min Typ Max A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.004 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D(1) 4.80 5.00 0.1890 0.197 E 3.80 4.00 0.15 0.157 e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ccc 0° (min), 8° (max) 0.10 0.0039 Figure 13. Package dimensions 11/11 Revision history 6 A5970D Revision history 7 Table 6. 12/11 Document revision history Date Revision Changes 06-Aug-2007 1 Initial release. 24-Oct-2007 2 Updated: Table 4 on page 5 2-May-2008 3 Updated: Cover page, Table 4 on page 5 27-Aug-2008 4 Updated: Coverpage and Table 4 on page 5 A5970D Please Read Carefully: Information in this document is provided solely in connection with ST products. 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