B5973D 2 A step down switching regulator for automotive applications Features ■ Qualified following the AEC-Q100 requirements (temperature Grade 1), see PPAP for more details. ■ 2 A DC output current ■ Operating input voltage from 4 V to 36 V ■ 3.3 V / (±2 %) reference voltage ■ 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 HSOP8 exposed pad Description The B5973D is a step down monolithic power switching regulator with a minimum switch current limit of 2.25 A so it is able to deliver up to 2 A DC current to the load depending on the application conditions. The output voltage can be set from 1.235 V to 35 V. The high current level is also achieved thanks to an SO8 package with exposed frame, that allows to reduce the Rth(JA) down to approximately 40 °C/W. The device uses an internal P-channel DMOS transistor (with a typical RDSon 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 4V only, it is particularly suitable for 5 V bus. Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection. Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection. Applications ■ Dedicated to automotive applications Figure 1. Typical application L1 15uH VIN=4V to 35V VCC 8 1 4 2 SYNCH COMP C4 C1 B A5973D 22nF R1 STPS340U 5k6 C2 330uF 6.3V 5 6 35V August 2008 D1 FB 10uF CERAMIC Vout=3.3V OUT C3 R3 220pF 4k7 VREF 3.3V 7 GND 3 INH R2 3k3 Rev 3 1/11 www.st.com 1 B5973D Contents Contents 1 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1/11 B5973D 1 Pin settings 1.1 Pin connection Figure 2. 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. 2/11 Electrical data B5973D 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 = 0.1μs -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 2.25 W Operating junction temperature range -40 to 150 °C Storage temperature range -55 to 150 °C SO8 Unit 40 (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 3/11 Value V8 V4 , V5 2.2 Parameter B5973D 3 Electrical characteristics Table 4. Electrical characteristics (TJ = -40 °C 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 = 2 A Min Max Unit 36 V 0.250 0.5 Ω 4 MOSFET on resistance Maximum limiting current (1) Typ VCC = 5 V 2.25 3 3.5 VCC = 5 V, TJ = 25 °C 2.5 3 3.5 212 250 280 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 Io sink Sink output current VCOMP = 1.9 V; VFB = 1.5 V Ib Source bias current Io source DC open loop gain 0.4 190 300 μA 1 1.5 mA 2.5 RL = ∞ V 50 65 4 μA dB 4/11 Electrical characteristics Table 4. Electrical characteristics (TJ = -40 °C to 125 °C, VCC = 12 V, unless otherwise specified) Symbol gm B5973D Parameter Transconductance Test condition Min ICOMP = -0.1 mA to 0.1 mA; Typ Max 2.3 Unit mS VCOMP = 1.9 V Synch function High input voltage VCC = 4.4 to 36 V; Low input voltage VCC = 4.4 to 36 V; Slave synch current Vsynch = 0.74 V (2) Vsynch = 2.33 V 2.5 0.11 0.21 VREF V 0.74 V 0.25 0.45 mA Master output amplitude Isource = 3 mA 2.75 3 V Output pulse width no load, Vsynch = 1.65 V 0.20 0.35 μs 3.2 3.3 3.399 V 5 10 mV 8 15 mV 18 35 mA Reference section Reference voltage IREF = 0 to 5 mA VCC = 4.4 V to 36 V Line regulation IREF = 0 mA VCC = 4.4 V to 36 V Load regulation Short circuit current IREF = 0 mA 5 1. With TJ = 85 °C, Ilim_min = 2.5 A, assured by design, characterization and statistical correlation. 2. Guarantee by design 5/11 B5973D 4 Typical characteristics Figure 3. Line regulation Figure 4. Shutdown current vs junction temperature Figure 5. Output voltage vs junction temperature Figure 6. Switching frequency vs junction temperature Figure 7. Quiescent current vs junction temperature 6/11 Typical characteristics Figure 8. B5973D Junction temperature vs output current Figure 10. Efficiency vs output current 7/11 Figure 9. Junction temperature vs output current Figure 11. Efficiency vs output current B5973D 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 8/11 Package mechanical data Table 5. B5973D HSOP8 mechanical data mm inch Dim Min Typ A Min Typ 1.70 Max 0.0669 A1 0.00 A2 1.25 b 0.31 0.51 0.0122 0.0201 c 0.17 0.25 0.0067 0.0098 D 4.80 4.90 5.00 0.1890 0.1929 0.1969 D1 3 3.1 3.2 0.118 0.122 0.126 E 5.80 6.00 6.20 0.2283 0.2441 E1 3.80 3.90 4.00 0.1496 0.1575 E2 2.31 2.41 2.51 0.091 e 0.10 0.00 0.0039 0.0492 0.095 0.099 1.27 h 0.25 0.50 0.0098 0.0197 L 0.40 1.27 0.0157 0.0500 k ccc Figure 12. Package dimensions 9/11 Max 0° (min), 8° (max) 0.10 0.0039 B5973D 6 Revision history Table 6. Document revision history Date Revision Changes 07-Nov-2007 1 Initial release 14-Jan-2008 2 Updated Table 5 on page 9 27-Aug-2008 3 Updated: Coverpage and Table 4 on page 4 10/11 B5973D Please Read Carefully: Information in this document is provided solely in connection with ST products. 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