Datasheet LT1938 (Analog Devices) - 5
| Manufacturer | Analog Devices |
| Description | 25V, 2.2A, 2.8MHz Step-Down Switching Regulator |
| Pages / Page | 24 / 5 — TYPICAL PERFORMANCE ChARACTERISTICS (TA = 25°C unless otherwise noted). … |
| File Format / Size | PDF / 271 Kb |
| Document Language | English |
TYPICAL PERFORMANCE ChARACTERISTICS (TA = 25°C unless otherwise noted). Feedback Voltage. Switching Frequency
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Text Version of Document
LT1938
TYPICAL PERFORMANCE ChARACTERISTICS (TA = 25°C unless otherwise noted) Feedback Voltage Switching Frequency Frequency Foldback
1.290 1.20 1200 RT = 45.3k RT = 45.3k 1.285 1.15 1000 1.280 1.10 800 TAGE (V) 1.275 1.05 1.270 1.00 600 1.265 0.95 FREQUENCY (MHz) 400 FEEDBACK VOL 1.260 0.90 SWITCHING FREQUENCY (kHz) 200 1.255 0.85 1.250 0.80 0 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 0 200 400 600 800 1000 1200 1400 TEMPERATURE (°C) TEMPERATURE (°C) FB PIN VOLTAGE (mV) 1938 G10 1938 G11 1938 G12
Minimum Switch On-Time Soft-Start RUN/SS Pin Current
140 4.0 12 120 3.5 10 3.0 100 8 2.5 80 2.0 6 60 1.5 4 40 1.0 SWITCH CURRENT LIMIT (A) RUN/SS PIN CURRENT (µA) MINIMUM SWITCH ON-TIME (ns) 20 2 0.5 0 0 0 –50 –25 0 25 50 75 100 125 0 0.5 1 1.5 2 2.5 3 3.5 0 5 10 15 20 25 TEMPERATURE (°C) RUN/SS PIN VOLTAGE (V) RUN/SS PIN VOLTAGE (V) 1938 G13 1938 G14 1938 G15
Boost Diode Error Amp Output Current Minimum Input Voltage
1.6 100 4.5 1.4 80 4.0 1.2 60 (V) f 40 1.0 3.5 20 TAGE (V) 0.8 0 0.6 3.0 BOOST DIODE V PIN CURRENT (µA) –20 INPUT VOL 0.4 V C –40 V 2.5 OUT = 3.3V T 0.2 A = 25°C –60 L = 4.7µH f = 800kHz 0 –80 2.0 0 0.5 1.0 1.5 2.0 1.065 1.165 1.265 1.365 1.465 0.001 0.01 0.1 1 10 BOOST DIODE CURRENT (A) FB PIN VOLTAGE (V) LOAD CURRENT (A) 1938 G16 1938 G17 1938 G18 1938fa 5 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL ChARACTERISTICS TYPICAL PERFORMANCE ChARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS
TYPICAL PERFORMANCE ChARACTERISTICS (TA = 25°C unless otherwise noted) Feedback Voltage Switching Frequency Frequency Foldback
1.290 1.20 1200 RT = 45.3k RT = 45.3k 1.285 1.15 1000 1.280 1.10 800 TAGE (V) 1.275 1.05 1.270 1.00 600 1.265 0.95 FREQUENCY (MHz) 400 FEEDBACK VOL 1.260 0.90 SWITCHING FREQUENCY (kHz) 200 1.255 0.85 1.250 0.80 0 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 0 200 400 600 800 1000 1200 1400 TEMPERATURE (°C) TEMPERATURE (°C) FB PIN VOLTAGE (mV) 1938 G10 1938 G11 1938 G12
Minimum Switch On-Time Soft-Start RUN/SS Pin Current
140 4.0 12 120 3.5 10 3.0 100 8 2.5 80 2.0 6 60 1.5 4 40 1.0 SWITCH CURRENT LIMIT (A) RUN/SS PIN CURRENT (µA) MINIMUM SWITCH ON-TIME (ns) 20 2 0.5 0 0 0 –50 –25 0 25 50 75 100 125 0 0.5 1 1.5 2 2.5 3 3.5 0 5 10 15 20 25 TEMPERATURE (°C) RUN/SS PIN VOLTAGE (V) RUN/SS PIN VOLTAGE (V) 1938 G13 1938 G14 1938 G15
Boost Diode Error Amp Output Current Minimum Input Voltage
1.6 100 4.5 1.4 80 4.0 1.2 60 (V) f 40 1.0 3.5 20 TAGE (V) 0.8 0 0.6 3.0 BOOST DIODE V PIN CURRENT (µA) –20 INPUT VOL 0.4 V C –40 V 2.5 OUT = 3.3V T 0.2 A = 25°C –60 L = 4.7µH f = 800kHz 0 –80 2.0 0 0.5 1.0 1.5 2.0 1.065 1.165 1.265 1.365 1.465 0.001 0.01 0.1 1 10 BOOST DIODE CURRENT (A) FB PIN VOLTAGE (V) LOAD CURRENT (A) 1938 G16 1938 G17 1938 G18 1938fa 5 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL ChARACTERISTICS TYPICAL PERFORMANCE ChARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS
