LM3668_15 Datasheet, PDF (6/30 Pages) Texas Instruments – 1-A, High-Efficiency Dual-Mode Single-Inductor Buck-Boost DC-DC Converter

LM3668
SNVS449O – JUNE 2007 – REVISED APRIL 2015
www.ti.com
7.6 Typical Characteristics
Typical Application Circuit (see Figure 46): V_IN = 3.6 V, L = 2.2 µH, C_IN = 10 µF, C_OUT = 22 µF⁽⁴⁾, T_A = 25°C , unless otherwise
stated.
900
800
IQ_5.5V
700
IQ_3.6V
600
500
400
IQ_2.5V
300
200
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Figure 1. Supply Current vs Temperature (Not Switching)
(V_OUT = 3.4 V)
150
NFET = 2.5V
125
NFET = 2.7V
100
75
50 NFET = 3.6V
NFET = 5.5V
25
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Figure 3. NFET_RDS (on) vs. Temperature (V_OUT = 3.4 V)
2.00
1.95
1.90
V_IN = 3.6V
1.85
1.80
1.75
1.70
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Figure 5. ILIMIT vs. Temperature (V_OUT = 3.4 V)
2.4
V_IN = 2.5V
2.3
2.2
V_IN = 3.6V
2.1
V_IN = 5.5V
2.0
1.9
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Figure 2. Switching Frequency vs. Temperature
(V_OUT = 3.4 V)
200
PFET_RDS = 2.5V PFET_RDS = 2.7V
175
150
125
100
75
PFET_RDS = 3.6V
50
25
PFET_RDS = 5.5V
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Figure 4. PFET_RDS (on) vs. Temperature (V_OUT = 3.4 V)
100
90
80
70
V_IN = 2.5V
60
V_IN = 2.7V
50
40
30
V_IN = 5.0V
20
V_IN = 5.5V
10
V_IN = 3.6V
0
0
1
10
100
1000
LOAD (mA)
Figure 6. Efficiency at V_OUT = 2.8 V (Forced PWM Mode)
(4) C_IN and C_OUT: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics. C_{OUT_MIN} should not
exceed −40% of suggested value. The preferable choice would be a type and make MLCC that issues –30% over the operating
temperature and voltage range.
6
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