Typical operating characteristics (continued) – Rainbow Electronics MAX1842 User Manual
Page 7
MAX1742/MAX1842
1A/2.7A, 1MHz, Step-Down Regulators with
Synchronous Rectification and Internal Switches
_______________________________________________________________________________________
7
Typical Operating Characteristics (continued)
(Circuit of Figure 1, T
A
= +25°C, unless otherwise noted.)
0.001
0.01
0.1
1
10
MAX1842
EFFICIENCY vs. OUTPUT CURRENT
(V
IN
= 5.0V, L = 2.5
µH)
MAX1842 toc11
OUTPUT CURRENT (A)
V
OUT
= 1.5V, R
TOFF
= 1OOk
Ω,
f
PWM
= 770kHz
V
OUT
= 1.8V, R
TOFF
= 75k
Ω,
f
PWM
= 910kHz
V
OUT
= 2.5V, R
TOFF
= 47k
Ω,
f
PWM
= 1070kHz
100
95
90
85
80
70
65
60
55
50
75
EFFICIENCY (%)
0.001
0.01
0.1
1
10
MAX1842
EFFICIENCY vs. OUTPUT CURRENT
(V
IN
= 3.3V, L = 1.5
µH)
MAX1842 toc12
OUTPUT CURRENT (A)
V
OUT
= 2.5V, R
TOFF
= 56k
Ω,
f
PWM
= 1000kHz
V
OUT
= 2.5V, R
TOFF
= 39k
Ω,
f
PWM
= 610kHz
V
OUT
= 1.8V, R
TOFF
= 43k
Ω,
f
PWM
= 1050kHz
100
95
90
85
80
70
65
60
55
50
75
EFFICIENCY (%)
0.001
0.01
0.1
1
10
MAX1842
EFFICIENCY vs. OUTPUT CURRENT
(f
PWM
= 270kHz)
MAX1842 toc13
I
OUT
(A)
V
IN
= 3.3V, V
OUT
= 1.8V,
L = 4.7
µH, R
TOFF
= 160k
Ω
100
95
90
85
80
70
65
60
55
50
75
EFFICIENCY (%)
V
IN
= 5V, V
OUT
= 1.8V, L = 5.6
µH,
R
TOFF
= 240k
Ω
MAX1842
NORMALIZED OUTPUT ERROR
vs. OUTPUT CURRENT
MAX1842 toc14
0.001
0.01
0.1
1
10
OUTPUT CURRENT (A)
V
IN
= 3.3V, V
OUT
= 1.5V, L = 1.5
µH
V
IN
= 5V, V
OUT
= 1.5V, L = 2.5
µH
0.1
0
-0.1
-0.2
-0.3
-0.4
NORMALIZED OUTPUT ERROR (%)
0
400
200
800
600
1000
1200
0
1.0
1.5
0.5
2.0
2.5
3.0
MAX1842
SWITCHING FREQUENCY
vs. OUTPUT CURRENT
MAX1842 toc15
OUTPUT CURRENT (A)
FREQUENCY (kHz)
V
IN
= 5V, V
OUT
= 2.5V, L = 2.5
µH
V
IN
= 3.3V, V
OUT
= 1.5V, L = 1.5
µH
V
IN
= 5V, V
OUT
= 1.5V, L = 2.5
µH
0
0
0
0
MAX1842
STARTUP AND SHUTDOWN
V
SS
2V/div
MAX1842 toc16
V
SHDN
5V/div
R
OUT
= 0.5
Ω, R
TOFF
= 56k
Ω
V
IN
= 3.3V, V
OUT
= 1.5V
I
INPUT
1A/div
V
OUTPUT
1V/div
1ms/div