Typical operating characteristics – Rainbow Electronics MAX1644 User Manual
Page 4
MAX1644
2A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
4
_______________________________________________________________________________________
Typical Operating Characteristics
(Circuit of Figure 1, T
A
= +25°C, unless otherwise noted.)
1
10
0
10
30
20
40
50
70
60
80
90
100
0.001
0.01
0.1
EFFICIENCY vs. OUTPUT CURRENT
MAX1644-01
OUTPUT CURRENT (A)
EFFICIENCY (%)
V
IN
= 5V, V
OUT
= 3.3V,
L = 6.0
µH, R
TOFF
= 120k
Ω
100
1
10
0
10
30
20
40
50
70
60
80
90
0.001
0.01
0.1
EFFICIENCY vs. OUTPUT CURRENT
MAX1644-02
OUTPUT CURRENT (A)
EFFICIENCY (%)
V
IN
= 3.3V, V
OUT
= 1.5V,
L = 4.7
µH, R
TOFF
= 200k
Ω
V
IN
= 5V, V
OUT
= 1.5V,
L = 6.0
µH, R
TOFF
= 270k
Ω
1
10
-1.0
-0.9
-0.7
-0.8
-0.6
-0.5
-0.3
-0.4
-0.2
-0.1
0
0.0001
0.001
0.01
0.1
DC LOAD-REGULATION ERROR
vs. OUTPUT CURRENT
MAX1644-03
OUTPUT CURRENT (A)
DC LOAD-REGULATION ERROR (%)
A
B
E
C
D
A: V
IN
= 3.3V, V
OUT
= 1.5V, L = 4.7
µH,
R
TOFF
= 200k
Ω, FBSEL = GND
B: V
IN
= 3.3V, V
OUT
= 1.5V, L = 4.7
µH,
R
TOFF
= 200k
Ω, FBSEL = REF
C: V
IN
= 5V, V
OUT
= 3.3V, L = 6.0
µH,
R
TOFF
= 120k
Ω, FBSEL = OPEN
D: V
IN
= 5V, V
OUT
= 1.5V, L = 6.0
µH,
R
TOFF
= 270k
Ω, FBSEL = GND
E: V
IN
= 5V, V
OUT
= 1.5V, L = 6.0
µH,
R
TOFF
= 270k
Ω, FBSEL = REF
0
100
50
250
200
150
300
350
0
1.0
0.5
1.5
2.0
SWITCHING FREQUENCY
vs. OUTPUT CURRENT
MAX1644-04
OUTPUT CURRENT (A)
SWITCHING FREQUENCY (kHz)
V
IN
= 3.3V,
V
OUT
= 1.5V,
L = 4.7
µH,
R
TOFF
= 200k
Ω
V
IN
= 5V,
V
OUT
= 1.5V,
L = 6.0
µH,
R
TOFF
= 270k
Ω
V
IN
= 5V,
V
OUT
= 3.3V,
L = 6.0
µH,
R
TOFF
= 120k
Ω
0
150
100
50
200
250
300
350
400
450
500
0
2
1
3
4
5
6
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1644-07
SUPPLY VOLTAGE
SUPPLY CURRENT I
CC
(µ
A)
0
0.03
0.02
0.01
0.04
0.05
0.06
0.07
0.08
0.09
0.10
SHUTDOWN SUPPLY CURRENT I
IN
+ I
CC
(µ
A)
I
OUT
= 0
UNDERVOLTAGE
LOCKOUT
SHDN = V
IN
= V
CC
SHDN = GND
0
1.0
0.5
2.5
2.0
1.5
4.0
3.5
3.0
4.5
0
200
100
300
400
500
600
OFF-TIME vs. R
TOFF
MAX1644-06
R
TOFF
(k
Ω)
t
OFF
(µ
s)
V
SHDN
5V/div
I
IN
1A/div
0
0
V
OUT
2V/div
V
SS
1V/div
0
0
2ms/div
START-UP AND
SHUTDOWN TRANSIENTS
MAX1644-09
V
IN
= 5.0V, V
OUT
= 3.3V, I
OUT
= 2A