Datasheet LTC3858 (Analog Devices) - 4
| Manufacturer | Analog Devices |
| Description | Low IQ, Dual 2-Phase Synchronous Step-Down Controller |
| Pages / Page | 38 / 4 — ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply … |
| File Format / Size | PDF / 434 Kb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply over the full operating
Model Line for this Datasheet
Text Version of Document
LTC3858
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TA = 25°C (Note 2). VIN = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
BG/TG t1D Bottom Gate Off to Top Gate On Delay CLOAD = 3300pF Each Driver 30 ns Top Switch-On Delay Time tON(MIN) Minimum On-Time (Note 7) 95 ns
INTVCC Linear Regulator
VINTVCCVIN Internal VCC Voltage 6V < VIN < 38V, VEXTVCC = 0V 4.85 5.1 5.35 V VLDOVIN INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 0V 0.7 1.1 % VINTVCCEXT Internal VCC Voltage 6V < VEXTVCC < 13V 4.85 5.1 5.35 V VLDOEXT INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 8.5V 0.6 1.1 % VEXTVCC EXTVCC Switchover Voltage EXTVCC Ramping Positive 4.5 4.7 4.9 V VLDOHYS EXTVCC Hysteresis Voltage 250 mV
Oscillator and Phase-Locked Loop
f25kΩ Programmable Frequency RFREQ = 25k, PLLIN/MODE = DC Voltage 105 kHz f65kΩ Programmable Frequency RFREQ = 65k, PLLIN/MODE = DC Voltage 375 440 505 kHz f105kΩ Programmable Frequency RFREQ = 105k, PLLIN/MODE = DC Voltage 835 kHz fLOW Low Fixed Frequency VFREQ = 0V, PLLIN/MODE = DC Voltage 320 350 380 kHz fHIGH High Fixed Frequency VFREQ = INTVCC, PLLIN/MODE = DC Voltage 485 535 585 kHz fSYNC Synchronizable Frequency PLLIN/MODE = External Clock l 75 850 kHz
PGOOD1 and PGOOD2 Outputs
VPGL PGOOD Voltage Low IPGOOD = 2mA 0.2 0.4 V IPGOOD PGOOD Leakage Current VPGOOD = 5V ±1 μA VPG PGOOD Trip Level VFB with Respect to Set Regulated Voltage VFB Ramping Negative –13 –10 –7 % Hysteresis 2.5 % VFB with Respect to Set Regulated Voltage VFB Ramping Positive 7 10 13 % Hysteresis 2.5 % tPG Delay for Reporting a Fault (PGOOD Low) 25 μs
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 3:
TJ is calculated from the ambient temperature TA and power may cause permanent damage to the device. Exposure to any Absolute dissipation PD according to the following formula: Maximum Ratings for extended periods may affect device reliability and TJ = TA + (PD • 34°C/W) lifetime.
Note 4:
The LTC3858 is tested in a feedback loop that servos VITH1,2 to a
Note 2:
The LTC3858 is tested under pulsed conditions such that TJ ≈ TA. specifi ed voltage and measures the resultant VFB1,2. The specifi cation at The LTC3858E is guaranteed to meet performance specifi cations from 85°C is not tested in production. This specifi cation is assured by design, 0°C to 85°C. Specifi cations over the –40°C to 125°C operating junction characterization and correlation to production testing at 125°C. temperature range are assured by design, characterization and correlation
Note 5:
Dynamic supply current is higher due to the gate charge being with statistical process controls. The LTC3858I is guaranteed over the delivered at the switching frequency. See Applications information. full –40°C to 125°C operating junction temperature range. Note that
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay the maximum ambient temperature is determined by specifi c operating times are measured using 50% levels conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors.
Note 7:
The minimum on-time condition is specifi ed for an inductor peak-to-peak ripple current ≥ of 40% IMAX (See Minimum On-Time Considerations in the Applications Information section). 3858fc 4
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TA = 25°C (Note 2). VIN = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
BG/TG t1D Bottom Gate Off to Top Gate On Delay CLOAD = 3300pF Each Driver 30 ns Top Switch-On Delay Time tON(MIN) Minimum On-Time (Note 7) 95 ns
INTVCC Linear Regulator
VINTVCCVIN Internal VCC Voltage 6V < VIN < 38V, VEXTVCC = 0V 4.85 5.1 5.35 V VLDOVIN INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 0V 0.7 1.1 % VINTVCCEXT Internal VCC Voltage 6V < VEXTVCC < 13V 4.85 5.1 5.35 V VLDOEXT INTVCC Load Regulation ICC = 0mA to 50mA, VEXTVCC = 8.5V 0.6 1.1 % VEXTVCC EXTVCC Switchover Voltage EXTVCC Ramping Positive 4.5 4.7 4.9 V VLDOHYS EXTVCC Hysteresis Voltage 250 mV
Oscillator and Phase-Locked Loop
f25kΩ Programmable Frequency RFREQ = 25k, PLLIN/MODE = DC Voltage 105 kHz f65kΩ Programmable Frequency RFREQ = 65k, PLLIN/MODE = DC Voltage 375 440 505 kHz f105kΩ Programmable Frequency RFREQ = 105k, PLLIN/MODE = DC Voltage 835 kHz fLOW Low Fixed Frequency VFREQ = 0V, PLLIN/MODE = DC Voltage 320 350 380 kHz fHIGH High Fixed Frequency VFREQ = INTVCC, PLLIN/MODE = DC Voltage 485 535 585 kHz fSYNC Synchronizable Frequency PLLIN/MODE = External Clock l 75 850 kHz
PGOOD1 and PGOOD2 Outputs
VPGL PGOOD Voltage Low IPGOOD = 2mA 0.2 0.4 V IPGOOD PGOOD Leakage Current VPGOOD = 5V ±1 μA VPG PGOOD Trip Level VFB with Respect to Set Regulated Voltage VFB Ramping Negative –13 –10 –7 % Hysteresis 2.5 % VFB with Respect to Set Regulated Voltage VFB Ramping Positive 7 10 13 % Hysteresis 2.5 % tPG Delay for Reporting a Fault (PGOOD Low) 25 μs
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 3:
TJ is calculated from the ambient temperature TA and power may cause permanent damage to the device. Exposure to any Absolute dissipation PD according to the following formula: Maximum Ratings for extended periods may affect device reliability and TJ = TA + (PD • 34°C/W) lifetime.
Note 4:
The LTC3858 is tested in a feedback loop that servos VITH1,2 to a
Note 2:
The LTC3858 is tested under pulsed conditions such that TJ ≈ TA. specifi ed voltage and measures the resultant VFB1,2. The specifi cation at The LTC3858E is guaranteed to meet performance specifi cations from 85°C is not tested in production. This specifi cation is assured by design, 0°C to 85°C. Specifi cations over the –40°C to 125°C operating junction characterization and correlation to production testing at 125°C. temperature range are assured by design, characterization and correlation
Note 5:
Dynamic supply current is higher due to the gate charge being with statistical process controls. The LTC3858I is guaranteed over the delivered at the switching frequency. See Applications information. full –40°C to 125°C operating junction temperature range. Note that
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay the maximum ambient temperature is determined by specifi c operating times are measured using 50% levels conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors.
Note 7:
The minimum on-time condition is specifi ed for an inductor peak-to-peak ripple current ≥ of 40% IMAX (See Minimum On-Time Considerations in the Applications Information section). 3858fc 4
