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LM2717-ADJ

www.ti.com

SNVS407C –DECEMBER 2005–REVISED MARCH 2013

LM2717-ADJ Dual Step-Down DC/DC Converter

Check for Samples: LM2717-ADJ

FEATURES

DESCRIPTION

The LM2717-ADJ is composed of two PWM DC/DC

• Adjustable Buck Converter with a 2.2A, 0.16Ω,

buck (step-down) converters. Both converters are

Internal Switch (Buck 1)

used to generate an adjustable output voltage as low

• Adjustable Buck Converter with a 3.2A, 0.16Ω,

as 1.267V. Both also feature low R

DSON

(0.16Ω)

Internal Switch (Buck 2)

internal switches for maximum efficiency. Operating

frequency can be adjusted anywhere between

• Operating Input Voltage Range of 4V to 20V

300kHz and 600kHz allowing the use of small

• Input Undervoltage Protection

external components. External soft-start pins for each

• 300kHz to 600kHz Pin Adjustable Operating

converter enables the user to tailor the soft-start

Frequency

times to a specific application. Each converter may

also be shut down independently with its own

• Over Temperature Protection

shutdown pin. The LM2717-ADJ is available in a low

• Small 24-Lead TSSOP Package

profile 24-lead TSSOP package ensuring a low profile

overall solution.

APPLICATIONS

• TFT-LCD Displays

• Handheld Devices

• Portable Applications

• Laptop Computers

• Automotive Applications

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (24 pages)

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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 LM2717-ADJ Dual Step-Down DC/DC Converter Check for Samples: LM2717-ADJ FEATURES DESCRIPTION • The LM2717-ADJ is composed of two PWM DC/DC buck (step-down) converters. Both converters are used to generate an adjustable output voltage as low as 1.267V. Both also feature low RDSON (0.16Ω) internal switches for maximum efficiency.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.com Typical Application Circuit CBOOT1 L1 RFB1 CSS1 CB1 SW1 SS1 SHDN1 RFB2 Buck Converter 1 FB1 CC1 RC1 VOUT1 COUT1 D1 VIN VIN CIN VC1 RF L2 FSLCT SW2 CSS2 VOUT2 D2 SS2 CB2 CBG VBG Buck Converter 2 COUT2 RFB3 CBOOT2 FB2 SHDN2 CC2 RC2 AGND VC2 RFB4 PGND LM2717 - ADJ Connection Diagram Figure 1.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 PIN DESCRIPTIONS Pin Name Function 1 PGND Power ground. PGND and AGND pins must be connected together directly at the part. 2 PGND Power ground. PGND and AGND pins must be connected together directly at the part. 3 AGND Analog ground. PGND and AGND pins must be connected together directly at the part. 4 FB1 Buck 1 output voltage feedback input. 5 VC1 Buck 1 compensation network connection.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) VIN −0.3V to 22V SW1 Voltage −0.3V to 22V SW2 Voltage −0.3V to 22V FB1, FB2 Voltages −0.3V to 7V CB1, CB2 Voltages −0.3V to VIN+7V (VIN=VSW) VC1 Voltage 1.75V ≤ VC1 ≤ 2.25V VC2 Voltage 0.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.com Electrical Characteristics Specifications in standard type face are for TJ = 25°C and those with boldface type apply over the full Operating Temperature Range (TJ = −40°C to +125°C). VIN = 5V, IL = 0A, and FSW = 300kHz unless otherwise specified. Symbol IQ Parameter Conditions Total Quiescent Current (both switchers) Min (1) Not Switching Typ (2) Max (1) Units 2.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 Electrical Characteristics (continued) Specifications in standard type face are for TJ = 25°C and those with boldface type apply over the full Operating Temperature Range (TJ = −40°C to +125°C). VIN = 5V, IL = 0A, and FSW = 300kHz unless otherwise specified. Symbol ThSHDN2 Parameter Buck 2 SHDN Threshold Conditions Output High Min Typ 1.8 1.36 (1) Output Low (2) Max (1) 1.33 0.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics Switching IQ vs. Input Voltage(FSW = 300kHz) 9 14 8 12 7 QUIESCENT CURRENT (mA) QUIESCENT CURRENT (PA) Shutdown IQ vs. Input Voltage 16 10 8 6 4 2 6 5 4 3 2 1 0 4 6 8 10 12 14 16 18 20 0 4 INPUT VOLTAGE (V) 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) Figure 2. Figure 3. Switching Frequency vs. Input Voltage(FSW = 300kHz) Buck 1 RDS(ON) vs.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 Typical Performance Characteristics (continued) Buck 2 Efficiency vs. Load Current(VOUT = 5V) 100 100 90 90 80 80 70 70 EFFICIENCY (%) EFFICIENCY (%) Buck 2 Efficiency vs. Load Current(VOUT = 15V) 60 50 40 30 60 50 40 30 20 20 V IN = 18V 10 0 0 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2 2.5 LOAD CURRENT (A) LOAD CURRENT (A) Figure 8. Figure 9. Buck 1 Switch Current Limit vs.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) Buck 1 Switch ON Resistance vs. Temperature Buck 2 Switch ON Resistance vs. Temperature 250 VIN = 8V POWER SWITCH R DSON (mW) POWER SWITCH R DSON (mW) 300 250 200 150 100 50 0 -40 -20 0 20 40 60 80 VIN = 8V 200 150 100 50 0 -40 -20 100 120 0 20 40 60 80 100 120 JUNCTION TEMPERATURE (°C) JUNCTION TEMPERATURE (°C) Figure 14. Figure 15. Switching Frequency vs.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 BUCK OPERATION PROTECTION (BOTH REGULATORS) The LM2717-ADJ has dedicated protection circuitry running during normal operation to protect the IC. The Thermal Shutdown circuitry turns off the power devices when the die temperature reaches excessive levels. The UVP comparator protects the power devices during supply power startup and shutdown to prevent operation at voltages less than the minimum input voltage.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.com INPUT CAPACITOR A low ESR aluminum, tantalum, or ceramic capacitor is needed between the input pin and power ground. This capacitor prevents large voltage transients from appearing at the input. The capacitor is selected based on the RMS current and voltage requirements. The RMS current is given by: (3) The RMS current reaches its maximum (IOUT/2) when VIN equals 2VOUT.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 BOOTSTRAP CAPACITOR A 4.7nF ceramic capacitor or larger is recommended for the bootstrap capacitor. For applications where the input voltage is less than twice the output voltage a larger capacitor is recommended, generally 0.1µF to 1µF to ensure plenty of gate drive for the internal switches and a consistently low RDSON.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.com 20 0 -45 -20 -90 Phase -40 PHASE (°) GAIN (dB) 0 GAIN (dB) Asymptotic -20 dB/ dec (fp1 is at zero frequency) -20 dB/ dec B fz1 -135 fp2 fz2 FREQUENCY Gain -60 10 100 1k 10k 100k -180 1M FREQUENCY (Hz) Figure 17. Control-Output Transfer Function Figure 18.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 where • • • B is the desired gain in V/V at fp (fz1) gm is the transconductance of the error amplifier 1 and R2 are the feedback resistors as shown in Figure 19 (13) A gain value around 10dB (3.3v/v) is generally a good starting point. Example: B = 3.3 v/v, gm=1350µmho, R1 = 20 KΩ, R2 = 59 KΩ: Rc1 = 3.3 x 20k + 59k | 9.76k 1350P 20k (14) Bandwidth will vary proportional to the value of Rc1.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 www.ti.com Note that the values calculated here give a good baseline for stability and will work well with most applications. The values in some cases may need to be adjusted some for optimum stability or the values may need to be adjusted depending on a particular applications bandwidth requirements.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 RFB2 RFB1 20k 33.2k 4.7 nF U1 CSS1 CC1 47 nF 20k 4.7 nF RC1 CBG 1 nF CC2 2k 4.7 nF RC2 CSS2 RF L1 22 mH CBOOT1 22.6k 47 nF AGND CB1 SW1 FB1 SHDN1 SS1 VC1 VIN VBG VIN VC2 SHDN2 CB2 SS2 FSLCT AGND AGND FB2 D1 MBRS240 *Connect CINA (pin 23) and CINB (pins 14,15) as close as possible to the VIN pins. VIN CBOOT2 1 mF PGND PGND PGND COUT1A 1 mF ceramic COUT1 68 mF 17V to 20V IN *CINB 4.
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LM2717-ADJ SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 RFB2 www.ti.com 20.5k 8.66k 1 mF U1 CSS1 CC1 47 nF 2k 82 nF RC1 CBG 1 nF CC2 2k 82 nF RC2 CSS2 RF L1 10 mH CBOOT1 RFB1 22.6k 47 nF AGND CB1 SW1 FB1 SHDN1 SS1 VC1 VIN VIN VBG VIN VC2 SHDN2 CB2 SS2 FSLCT AGND AGND FB2 *Connect CINA (pin 23) and CINB (pins 14,15) as close as possible to the VIN pins. CBOOT2 1 mF *CINB 4.
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LM2717-ADJ www.ti.com SNVS407C – DECEMBER 2005 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision B (March 2013) to Revision C • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM2717MTX-ADJ/NOPB Package Package Pins Type Drawing TSSOP PW 24 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 2500 330.0 16.4 Pack Materials-Page 1 6.95 B0 (mm) K0 (mm) P1 (mm) 8.3 1.6 8.0 W Pin1 (mm) Quadrant 16.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2717MTX-ADJ/NOPB TSSOP PW 24 2500 367.0 367.0 35.
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