Datasheet LTC1779 (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | 250mA Current Mode Step-Down DC/DC Converter in SOT-23 |
| Pages / Page | 14 / 3 — e lecTrical characTerisTics The. denotes specifications that apply over … |
| File Format / Size | PDF / 267 Kb |
| Document Language | English |
e lecTrical characTerisTics The. denotes specifications that apply over the full operating temperature
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LTC1779
e lecTrical characTerisTics The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 4.2V unless otherwise specified. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS
Input DC Supply Current Typicals at VIN = 4.2V (Note 4) Normal Operation 2.5V ≤ VIN ≤ 9.8V 135 240 µA Shutdown 2.5V ≤ VIN ≤ 9.8V, VITH/RUN = 0V 8 22 µA UVLO VIN < UVLO Threshold 1 13 µA Undervoltage Lockout Threshold VIN Falling l 1.60 2.0 V VIN Rising 2.1 2.5 V Shutdown Threshold (at ITH/RUN) l 0.15 0.325 0.5 V Start-Up Current Source VITH/RUN = 0V 0.25 0.5 0.85 µA Regulated Feedback Voltage (Note 5) 0°C to 70°C l 0.780 0.800 0.820 V (Note 5) –40°C to 85°C l 0.770 0.800 0.830 V Output Voltage Line Regulation 2.5V ≤ VIN ≤ 9.8V (Note 5) –3 0 3 mV/V Output Voltage Load Regulation ITH/RUN Sinking 5µA (Note 5) 2.5 mV/µA ITH/RUN Sourcing 5µA (Note 5) 2.5 mV/µA VFB Input Current (Note 5) 5 25 nA Overvoltage Protect Threshold Measured at VFB 0.820 0.860 0.895 V Overvoltage Protect Hysteresis 30 mV Overtemperature Protect Threshold 170 °C Overtemperature Protect Hysteresis 15 °C Oscillator Frequency VFB = 0.8V 500 550 650 kHz VFB = 0V 100 kHz RDS(ON) of Internal P-Channel FET VIN = 4.2V, ISW = 100mA 0.85 1.4 Ω Peak Current Sense Voltage (Note 6) 120 mV
Note 1:
Absolute Maximum Ratings are those values beyond which the life
Note 4:
Dynamic supply current is higher due to the gate charge being of a device may be impaired. delivered at the switching frequency.
Note 2:
The LTC1779E is guaranteed to meet performance specifications
Note 5:
The LTC1779 is tested in a feedback loop that servos VFB to the from 0°C to 70°C. Specifications over the –40°C to 85°C operating output of the error amplifier. temperature range are assured by design, characterization and correlation
Note 6:
Peak current sense voltage is reduced dependent upon duty cycle with statistical process controls. to a percentage of value as given in Figure 2.
Note 3:
TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD • θJ°C/W) 1779fa For more information www.linear.com/LTC1779 3
e lecTrical characTerisTics The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 4.2V unless otherwise specified. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS
Input DC Supply Current Typicals at VIN = 4.2V (Note 4) Normal Operation 2.5V ≤ VIN ≤ 9.8V 135 240 µA Shutdown 2.5V ≤ VIN ≤ 9.8V, VITH/RUN = 0V 8 22 µA UVLO VIN < UVLO Threshold 1 13 µA Undervoltage Lockout Threshold VIN Falling l 1.60 2.0 V VIN Rising 2.1 2.5 V Shutdown Threshold (at ITH/RUN) l 0.15 0.325 0.5 V Start-Up Current Source VITH/RUN = 0V 0.25 0.5 0.85 µA Regulated Feedback Voltage (Note 5) 0°C to 70°C l 0.780 0.800 0.820 V (Note 5) –40°C to 85°C l 0.770 0.800 0.830 V Output Voltage Line Regulation 2.5V ≤ VIN ≤ 9.8V (Note 5) –3 0 3 mV/V Output Voltage Load Regulation ITH/RUN Sinking 5µA (Note 5) 2.5 mV/µA ITH/RUN Sourcing 5µA (Note 5) 2.5 mV/µA VFB Input Current (Note 5) 5 25 nA Overvoltage Protect Threshold Measured at VFB 0.820 0.860 0.895 V Overvoltage Protect Hysteresis 30 mV Overtemperature Protect Threshold 170 °C Overtemperature Protect Hysteresis 15 °C Oscillator Frequency VFB = 0.8V 500 550 650 kHz VFB = 0V 100 kHz RDS(ON) of Internal P-Channel FET VIN = 4.2V, ISW = 100mA 0.85 1.4 Ω Peak Current Sense Voltage (Note 6) 120 mV
Note 1:
Absolute Maximum Ratings are those values beyond which the life
Note 4:
Dynamic supply current is higher due to the gate charge being of a device may be impaired. delivered at the switching frequency.
Note 2:
The LTC1779E is guaranteed to meet performance specifications
Note 5:
The LTC1779 is tested in a feedback loop that servos VFB to the from 0°C to 70°C. Specifications over the –40°C to 85°C operating output of the error amplifier. temperature range are assured by design, characterization and correlation
Note 6:
Peak current sense voltage is reduced dependent upon duty cycle with statistical process controls. to a percentage of value as given in Figure 2.
Note 3:
TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD • θJ°C/W) 1779fa For more information www.linear.com/LTC1779 3
