Datasheet LT1945 (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | Dual Micropower DC/DC Converter with Positive and Negative Outputs |
| Pages / Page | 8 / 3 — ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply … |
| File Format / Size | PDF / 129 Kb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply over the full operating
Model Line for this Datasheet
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LT1945
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 1.2V, VSHDN = 1.2V unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS
SHDN Pin Current VSHDN = 1.2V 2 3 μA VSHDN = 5V 8 12 μA SHDN Input Voltage High 0.9 V SHDN Input Voltage Low 0.25 V Switch Leakage Current Switch Off, VSW = 5V 0.01 5 μA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings may characterization and correlation with statistical process controls. The cause permanent damage to the device. Exposure to any Absolute Maximum LT1945I is guaranteed over the full –40°C to 125°C operating junction Rating condition for extended periods may affect device reliability and lifetime. temperature range.
Note 2:
The LT1945E is guaranteed to meet performance specifi cations
Note 3:
Bias current fl ows out of the NFB1 pin. from 0°C to 70°C junction temperature. Specifi cations over the –40°C
Note 4:
Bias current fl ows into the FB2 pin. to 85°C operating junction temperature range are assured by design,
Note 5:
See Figure 1 for Switcher 1 and Switcher 2 locations.
TYPICAL PERFORMANCE CHARACTERISTICS Switch Saturation Voltage FB2 Pin Voltage and NFB1 Pin Voltage and (VCESAT) Bias Current Bias Current
0.60 1.25 50 –1.25 5 0.55 0.50 1.24 40 –1.24 4 BIAS CURRENT (nA) 0.45 BIAS CURRENT (mA) VOLTAGE VOLTAGE ISWITCH = 500mA 0.40 1.23 30 –1.23 3 0.35 0.30 1.22 CURRENT 20 –1.22 2 ISWITCH = 300mA SWITCH VOLTAGE (V) 0.25 CURRENT FEEDBACK VOLTAGE (V) FEEDBACK VOLTAGE (V) 0.20 1.21 10 –1.21 1 0.15 0.10 1.20 0 –1.20 0 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1945 G01 1945 G02 1945 G03
Switch Off Time Switch Current Limit Quiescent Current
550 400 25 VIN = 12V VFB = 1.23V 350 NOT SWITCHING 500 VIN = 1.2V 23 300 450 250 21 V 400 IN = 1.2V 200 VIN = 12V V 19 IN = 12V 150 350 SWITCH OFF TIME (ns) PEAK CURRENT (mA) VIN = 1.2V 100 QUIESCENT CURRENT (μA) 17 300 50 250 0 15 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1945 G04 1945 G05 1945 G06 1945fa 3
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 1.2V, VSHDN = 1.2V unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS
SHDN Pin Current VSHDN = 1.2V 2 3 μA VSHDN = 5V 8 12 μA SHDN Input Voltage High 0.9 V SHDN Input Voltage Low 0.25 V Switch Leakage Current Switch Off, VSW = 5V 0.01 5 μA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings may characterization and correlation with statistical process controls. The cause permanent damage to the device. Exposure to any Absolute Maximum LT1945I is guaranteed over the full –40°C to 125°C operating junction Rating condition for extended periods may affect device reliability and lifetime. temperature range.
Note 2:
The LT1945E is guaranteed to meet performance specifi cations
Note 3:
Bias current fl ows out of the NFB1 pin. from 0°C to 70°C junction temperature. Specifi cations over the –40°C
Note 4:
Bias current fl ows into the FB2 pin. to 85°C operating junction temperature range are assured by design,
Note 5:
See Figure 1 for Switcher 1 and Switcher 2 locations.
TYPICAL PERFORMANCE CHARACTERISTICS Switch Saturation Voltage FB2 Pin Voltage and NFB1 Pin Voltage and (VCESAT) Bias Current Bias Current
0.60 1.25 50 –1.25 5 0.55 0.50 1.24 40 –1.24 4 BIAS CURRENT (nA) 0.45 BIAS CURRENT (mA) VOLTAGE VOLTAGE ISWITCH = 500mA 0.40 1.23 30 –1.23 3 0.35 0.30 1.22 CURRENT 20 –1.22 2 ISWITCH = 300mA SWITCH VOLTAGE (V) 0.25 CURRENT FEEDBACK VOLTAGE (V) FEEDBACK VOLTAGE (V) 0.20 1.21 10 –1.21 1 0.15 0.10 1.20 0 –1.20 0 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1945 G01 1945 G02 1945 G03
Switch Off Time Switch Current Limit Quiescent Current
550 400 25 VIN = 12V VFB = 1.23V 350 NOT SWITCHING 500 VIN = 1.2V 23 300 450 250 21 V 400 IN = 1.2V 200 VIN = 12V V 19 IN = 12V 150 350 SWITCH OFF TIME (ns) PEAK CURRENT (mA) VIN = 1.2V 100 QUIESCENT CURRENT (μA) 17 300 50 250 0 15 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1945 G04 1945 G05 1945 G06 1945fa 3
