Datasheet LTC7812 (Analog Devices) - 4
| Manufacturer | Analog Devices |
| Description | Low IQ, 38V Synchronous Boost+Buck Controller |
| Pages / Page | 44 / 4 — ELECTRICAL. CHARACTERISTICS The. denotes the specifications which apply … |
| File Format / Size | PDF / 2.3 Mb |
| Document Language | English |
ELECTRICAL. CHARACTERISTICS The. denotes the specifications which apply over the specified operating
Model Line for this Datasheet
Text Version of Document
LTC7812
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C. VBIAS = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Maximum Duty Factor for TG Buck (Channel 1) in Dropout, FREQ = 0V 98 99 % Boost (Channel 2) in Overvoltage 100 % Maximum Duty Factor for BG Buck (Channel 1) in Overvoltage 100 % Boost (Channel 2) 96 % ITRACK/SS1 Soft-Start Charge Current VTRACK/SS1 = 0V 3 5 8 µA ISS2 Soft-Start Charge Current VSS2 = 0V 3 5 8 µA VRUN1 ON RUN1 Pin Threshold VRUN1 Rising l 1.18 1.24 1.32 V VRUN2 ON RUN2 Pin Threshold VRUN2 Rising l 1.21 1.27 1.33 V RUN Pin Hysteresis 70 mV VSENSE1,2,(MAX) Maximum Current Sense Threshold VFB1 = 0.7V, VSENSE1– = 3.3V l 43 50 57 mV VFB2 = 1.1V, VSENSE2+ = 12V
Gate Driver
TG1 Pull-Up On-Resistance 2.5 Ω TG1 Pull-Down On-Resistance 1.5 Ω BG1 Pull-Up On-Resistance 2.4 Ω BG1 Pull-Down On-Resistance 1.1 Ω TG2 Pull-Up On-Resistance 1.2 Ω TG2 Pull-Down On-Resistance 1.0 Ω BG2 Pull-Up On-Resistance 1.2 Ω BG2 Pull-Down On-Resistance 1.0 Ω TG Transition Time: (Note 6) Rise Time CLOAD = 3300pF 25 ns Fall Time CLOAD = 3300pF 16 ns BG Transition Time: (Note 6) Rise Time CLOAD = 3300pF 28 ns Fall Time CLOAD = 3300pF 13 ns Top Gate Off to Bottom Gate On Delay CLOAD = 3300pF Each Driver Buck (Channel 1) 30 ns Synchronous Switch-On Delay Time Boost (Channel 2) 70 ns Bottom Gate Off to Top Gate On Delay CLOAD = 3300pF Each Driver Buck (Channel 1) 30 ns Top Switch-On Delay Time Boost (Channel 2) 70 ns tON(MIN)1 Buck Minimum On-Time (Note 7) 95 ns tON(MIN)2 Boost Minimum On-Time (Note 7) 120 ns
INTVCC Linear Regulator
Internal VCC Voltage 6V < VBIAS < 38V, VEXTVCC = 0V, IINTVCC = 0mA 5.0 5.4 5.6 V INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 0V 0.7 2 % Internal VCC Voltage 6V < VEXTVCC < 13V, IINTVCC = 0mA 5.0 5.4 5.6 V INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 8.5V 0.7 2 % EXTVCC Switchover Voltage EXTVCC Ramping Positive 4.5 4.7 V EXTVCC Hysteresis 200 mV
Oscillator and Phase-Locked Loop
Programmable Frequency RFREQ = 25k; PLLIN/MODE = DC Voltage 115 kHz RFREQ = 65k; PLLIN/MODE = DC Voltage 440 kHz RFREQ = 105k; PLLIN/MODE = DC Voltage 835 kHz Low Fixed Frequency VFREQ = 0V PLLIN/MODE = DC Voltage 320 350 380 kHz 7812fc 4 For more information www.linear.com/LTC7812 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Typical Application Related Parts
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C. VBIAS = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Maximum Duty Factor for TG Buck (Channel 1) in Dropout, FREQ = 0V 98 99 % Boost (Channel 2) in Overvoltage 100 % Maximum Duty Factor for BG Buck (Channel 1) in Overvoltage 100 % Boost (Channel 2) 96 % ITRACK/SS1 Soft-Start Charge Current VTRACK/SS1 = 0V 3 5 8 µA ISS2 Soft-Start Charge Current VSS2 = 0V 3 5 8 µA VRUN1 ON RUN1 Pin Threshold VRUN1 Rising l 1.18 1.24 1.32 V VRUN2 ON RUN2 Pin Threshold VRUN2 Rising l 1.21 1.27 1.33 V RUN Pin Hysteresis 70 mV VSENSE1,2,(MAX) Maximum Current Sense Threshold VFB1 = 0.7V, VSENSE1– = 3.3V l 43 50 57 mV VFB2 = 1.1V, VSENSE2+ = 12V
Gate Driver
TG1 Pull-Up On-Resistance 2.5 Ω TG1 Pull-Down On-Resistance 1.5 Ω BG1 Pull-Up On-Resistance 2.4 Ω BG1 Pull-Down On-Resistance 1.1 Ω TG2 Pull-Up On-Resistance 1.2 Ω TG2 Pull-Down On-Resistance 1.0 Ω BG2 Pull-Up On-Resistance 1.2 Ω BG2 Pull-Down On-Resistance 1.0 Ω TG Transition Time: (Note 6) Rise Time CLOAD = 3300pF 25 ns Fall Time CLOAD = 3300pF 16 ns BG Transition Time: (Note 6) Rise Time CLOAD = 3300pF 28 ns Fall Time CLOAD = 3300pF 13 ns Top Gate Off to Bottom Gate On Delay CLOAD = 3300pF Each Driver Buck (Channel 1) 30 ns Synchronous Switch-On Delay Time Boost (Channel 2) 70 ns Bottom Gate Off to Top Gate On Delay CLOAD = 3300pF Each Driver Buck (Channel 1) 30 ns Top Switch-On Delay Time Boost (Channel 2) 70 ns tON(MIN)1 Buck Minimum On-Time (Note 7) 95 ns tON(MIN)2 Boost Minimum On-Time (Note 7) 120 ns
INTVCC Linear Regulator
Internal VCC Voltage 6V < VBIAS < 38V, VEXTVCC = 0V, IINTVCC = 0mA 5.0 5.4 5.6 V INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 0V 0.7 2 % Internal VCC Voltage 6V < VEXTVCC < 13V, IINTVCC = 0mA 5.0 5.4 5.6 V INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 8.5V 0.7 2 % EXTVCC Switchover Voltage EXTVCC Ramping Positive 4.5 4.7 V EXTVCC Hysteresis 200 mV
Oscillator and Phase-Locked Loop
Programmable Frequency RFREQ = 25k; PLLIN/MODE = DC Voltage 115 kHz RFREQ = 65k; PLLIN/MODE = DC Voltage 440 kHz RFREQ = 105k; PLLIN/MODE = DC Voltage 835 kHz Low Fixed Frequency VFREQ = 0V PLLIN/MODE = DC Voltage 320 350 380 kHz 7812fc 4 For more information www.linear.com/LTC7812 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Typical Application Related Parts
