Typical operating characteristics (continued) – Rainbow Electronics MAX1821 User Manual
Page 6
MAX1820/MAX1821
WCDMA Cellular Phone 600mA
Buck Regulators
6
_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
90
0
1
1000
100
10
MAX1821 EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 3.3V)
30
10
70
50
100
40
20
80
60
MAX1820/21 toc04
LOAD CURRENT (mA)
EFFICIENCY (%)
V
IN
= 5.0V
V
IN
= 3.6V
V
IN
= 5.0V
SKIP = GND (DASHED LINE)
SKIP = BATT (SOLID LINE)
V
IN
= 3.6V
90
0
1
1000
100
10
MAX1821 EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 2.5V)
30
10
70
50
100
40
20
80
60
MAX1820/21 toc05
LOAD CURRENT (mA)
EFFICIENCY (%)
V
IN
= 5.0V
V
IN
= 3.6V
V
IN
= 3.6V
V
IN
= 5.0V
SKIP = GND (DASHED LINE)
SKIP = BATT (SOLID LINE)
V
IN
= 2.7V
V
IN
= 2.7V
90
0
1
1000
100
10
MAX1821 EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 1.5V)
30
10
70
50
100
40
20
80
60
MAX1820/21 toc06
LOAD CURRENT (mA)
EFFICIENCY (%)
V
IN
= 5.0V
V
IN
= 3.6V
SKIP = GND (DASHED LINE)
SKIP = BATT (SOLID LINE)
V
IN
= 2.7V
0
40
20
80
60
120
100
140
0
200
300
100
400
500
600
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX1820/21 toc07
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
V
OUT
= 3.4V
RL = 57m
Ω
0
2
1
5
4
3
8
7
6
9
2.0
3.0
3.5
2.5
4.0
4.5
5.0
5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1820/21 toc08
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
V
OUT
= 1.5V
SKIP = BATT
20
80
60
40
120
100
200
180
160
140
220
2.0
2.5
3.0
3.5 4.0
4.5
5.0
5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1820/21 toc09
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (
µ
A)
V
OUT
= 1.5V
SKIP = GND
MAX1820/21 toc10
B
C
A
400ns/div
A: V
LX
, 5V/div
B: INDUCTOR CURRENT, 500mA/div
C: V
OUT
(AC-COUPLED), 5mV/div
HEAVY-LOAD SWITCHING WAVEFORMS
(V
IN
= 3.8V, V
OUT
= 3.4V,
I
LOAD
= 600mA, SKIP = BATT)
MAX1820/21 toc11
B
C
A
400ns/div
A: V
LX
, 5V/div
B: INDUCTOR CURRENT, 500mA/div
C: V
OUT
(AC-COUPLED), 5mV/div
MEDIUM-LOAD SWITCHING WAVEFORMS
(V
IN
= 3.8V, V
OUT
= 1.8V,
I
LOAD
= 300mA, SKIP = BATT)
MAX1820/21 toc12
B
C
A
400ns/div
A: V
LX
, 5V/div
B: INDUCTOR CURRENT, 100mA/div
C: V
OUT
(AC-COUPLED), 5mV/div
LIGHT-LOAD PWM SWITCHING WAVEFORMS
(V
IN
= 3.8V, V
OUT
= 0.45V,
I
LOAD
= 30mA, SKIP = BATT)