L6731BTR STMicroelectronics, L6731BTR Datasheet
L6731BTR
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L6731BTR Summary of contents
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... Sink/source capability for ddr memory and termination supply ■ Over voltage protection ■ Thermal shut-down ■ Package: HTSSOP16 Order Codes Part number L6731B L6731BTR June 2006 within DDQ Applications ■ High performance / high density DC-DC DS(on) modules ■ Low voltage distributed DC-DC ■ ...
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Contents Contents 1 Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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L6731B 1 Summary description The controller is an integrated circuit realized in BCD5 (BiCMOS-DMOS, version 5) fabrication that provides complete control logic and protection for high performance step-down DC-DC and niPOL converters designed to drive N-Channel MOSFETs in ...
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Summary description 1.1 Functional description Figure 1. Block Diagram OCL SS/INH Protection and Ref DDR- PGOOD + VTTREF 4/24 V =4.5V to14V CC OCH VCCDR VCC LDO Monitor OSC - L6731B - + 0. PWM E/A ...
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L6731B 2 Electrical data 2.1 Maximum rating Table 1. Absolute maximum ratings Symbol GND and PGND, OCH, PGOOD Boot Voltage BOOT - PHASE V V HGATE - PHASE V BOOT BOOT PHASE V ...
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Pin connections and functions 3 Pin connections and functions Figure 2. Pins connection ( Top view) PGOOD VTTREF SS/INH DDR-IN Table 3. Pin functions Pin n. Name This pin is an open collector output and it is pulled low if ...
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L6731B Table 3. Pin functions A resistor connected from this pin to ground sets the valley- current-limit. The valley current is sensed through the low-side MOSFET(s). The internal current generator sources a current of 100µ OCL 8 OCL ...
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Electrical characteristics 4 Electrical characteristics V = 12V 25°C unless otherwise specified Table 4. Electrical Characteristics Symbol Parameter V SUPPLY CURRENT CC V Stand By current quiescent current CC Power-ON V Turn-ON ...
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L6731B Table 4. Electrical Characteristics Symbol Parameter Error Amplifier R EAREF Input Resistance EAREF I I.I. bias current FB Ext Ref Clamp V Error amplifier offset OFFSET G Open Loop Voltage Gain V GBWP Gain-Bandwidth Product SR Slew-Rate Gate Drivers ...
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Device description 5 Device description 5.1 Oscillator The switching frequency can be fixed to two values: 250KHz or 500KHz by setting the proper voltage at the EAREF pin (see reference). 5.2 Internal LDO An internal LDO supplies the internal circuitry ...
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L6731B 5.3 Bypassing the LDO to avoid the voltage drop with low Vcc the internal LDO works in dropout with an output resistance of about 1 . The CC maximum LDO output current is about 100mA and ...
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Device description 5.5 Error amplifier Figure 5. Error Amplifier Reference V CCDR DDR-IN 100K 5.6 Soft start When both V and V CC the start-up phase takes place. Otherwise the SS pin is internally shorted to GND. At start-up, a ...
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L6731B The output of the error amplifier is clamped with this voltage (Vss) until it reaches the programmed value. No switching activity is observable if V MOSFETs are off. When Vss is between 0.5V and 1.1V the low-side MOSFET is ...
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Device description 5.8 Monitoring and protections The output voltage is monitored by means of pin FB not within ±10% (typ.) of the programmed value, the Power-Good (PGOOD) output is forced low. The device provides over- voltage-protection: when ...
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L6731B Figure 8. OVP: the low-side MOSFET is turned-on in advance. The device realizes the over-current-protection (OCP) sensing the current both on the high- side MOSFET(s) and the low-side MOSFET(s) and so 2 current limit thresholds can be set (see ...
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Device description 5.9 HICCUP mode during an OCP Figure 9. Constant current and Hiccup Mode during an OCP. 5.10 Thermal shutdown When the junction temperature reaches 150°C ±10°C the device enters in thermal shutdown. Both MOSFETs are turned off and ...
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L6731B 5.11 Minimum on-time (T The device can manage minimum on-times lower than 100ns. This feature comes down from the control topology and from the particular over-current-protection system of the L6731B. In fact voltage mode controller the current ...
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Application details 6 Application details 6.1 Inductor design The inductance value is defined by a compromise between the transient response time, the efficiency, the cost and the size. The inductor has to be calculated to sustain the output and the ...
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L6731B 6.3 Input capacitors The input capacitors have to sustain the RMS current flowing through them, that is: Where D is the duty cycle. The equation reaches its maximum value, I losses in worst case are: 6.4 Compensation network The ...
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Application details The compensation network consists in the internal error amplifier, the impedance networks Z (R3, R4 and C20) and Z closed loop transfer function with the highest 0dB crossing frequency to have fastest transient response (but always lower than ...
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L6731B 7 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 ...
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Package mechanical data Table 6. HTSSOP16 mechanical data DIM. MIN 0.8 b 0.19 c 0.09 D 4.9 D1 1.7 E 6.2 E1 4 0° L 0.45 Figure 13. Package dimensions 22/24 mm. TYP ...
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L6731B 8 Revision history Table 7. Revision history Date Revision 22-Dec-2005 31-May-2006 26-Jun-2006 1 Initial release 2 New template, thermal data updated 3 Note page 5 deleted Revision history Changes 23/24 ...
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