Datasheet MAX1698, MAX1698A (Maxim) - 4

High-Efficiency Step-Up Current Regulator for LEDs Typical Operating Characteristics
(Circuit of Figure 2, VCC = VBATT = 3.3V, VADJ = VREF, TA = +25°C, unless otherwise noted.)
NORMALIZED OUTPUT CURRENT OUTPUT CURRENT OUTPUT CURRENT vs. VBATT AND VCC vs. ADJ VOLTAGE vs. INPUT VOLTAGE
25 1.2 22.0 vs. VBATT MXA1698-01 1.0 MXA1698-02 MXA1698-03 20 vs. VCC 21.5 0.8 15 0.6 21.0 10 0.4 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 20.5 5 NORMALIZED OUTPUT CURRENT 0.2 1 CHAIN OF 4 LEDs 1 CHAIN OF 4 LEDs 0 0 20.0 0 1 2 3 4 5 6 7 8 9 10 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 2 4 6 8 10 12 14 16 18 20
MAX1698/MAX1698A
VBATT, VCC (V) ADJ VOLTAGE (V) INPUT VOLTAGE (V)
BATTERY CURRENT vs. BATTERY VOLTAGE EXT RISE/FALL TIME vs. CEXT EFFICIENCY vs. BATTERY VOLTAGE
1000 100 100 4 CHAINS OF 4 LEDs 900 90 90 MXA1698-04 MXA1698-05 MXA1698-06 800 80 80 RISE TIME 700 IBATT 70 70 (mA) 600 60 60 500 I BATT 50 50 FALL TIME 400 I OUT, 40 40 EFFICIENCY (%) 300 RISE/FALL TIME (ns) 30 30 200 20 20 IOUT 100 10 10 IOUT = 80mA 4 CHAINS OF 4 LEDs 0 0 0 0 1 2 3 4 5 6 7 8 9 10 100 400 700 1000 1300 1600 1900 2200 0 2 4 6 8 10 VBATT (V) CEXT (pF) BATTERY VOLTAGE (V)
LED AND INDUCTOR CURRENT EFFICIENCY vs. OUTPUT CURRENT SHUTDOWN/SOFT-START TIMING WAVEFORMS
100 MXA1698-08 MXA1698-09 90 MXA1698-07 I 80 OUT LED 50mA/div CURRENT 70 50mA/div 60 50 IBATT 40 100mA/div EFFICIENCY (%) 30 INDUCTOR CURRENT 20 3.3V 500mA/div SHDN 10 VBATT = 5V 0 4 CHAINS OF 4 LEDs 5V/div IOUT SET TO 80mA, 4 CHAINS OF 4 LEDs 0 5 15 25 35 45 55 65 75 85 5ms/div 1µs/div OUTPUT CURRENT (mA)
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