Low-Cost, High-Frequency, Current-Mode PWM
Buck Controller
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 5V, V
BST
- V
LX
= 5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
ILIM Input Impedance
MAX1953 only
V
PGND
- V
LX
, ILIM = GND (MAX1953 only)
Current-Limit Threshold
V
PGND
- V
LX
, ILIM = open (MAX1953 only)
V
PGND
- V
LX
, ILIM = IN (MAX1953 only)
V
PGND
– V
LX
(MAX1954/MAX1957 only)
OSCILLATOR
Switching Frequency
Maximum Duty Cycle
Minimum Duty Cycle
SOFT-START
Soft-Start Period
FET DRIVERS
DH On-Resistance, High State
DH On-Resistance, Low State
DL On-Resistance, High State
DL On-Resistance, Low State
LX, BST Leakage Current
LX, BST, HSD Leakage Current
THERMAL PROTECTION
Thermal Shutdown
Thermal Shutdown Hysteresis
SHUTDOWN CONTROL
COMP Logic Level Low
COMP Logic Level High
COMP Pullup Current
3V < V
IN
< 5.5V
3V < V
IN
< 5.5V
0.8
100
0.25
V
V
µA
Rising temperature
160
15
°C
°C
V
BST
= 10.5V, V
LX
= V
IN
= 5.5V,
MAX1953/MAX1957
V
BST
= 18.7V, V
LX
= 13.2V, V
IN
= 5.5V
V
HSD
= 13.2V (MAX1954 only)
2
1.5
2
0.8
3
3
3
2
20
30
Ω
Ω
Ω
Ω
µA
µA
MAX1953
MAX1954/MAX1957
4
3.4
ms
MAX1953
MAX1954/MAX1957
Measured at DH
MAX1953, measured at DH
MAX1954/MAX1957, measured at DH
0.8
240
86
1
300
89
15
4.5
1.2
360
96
18
5.5
MHz
kHz
%
%
CONDITIONS
MIN
50
85
190
290
190
TYP
125
105
210
320
210
MAX
200
125
235
350
235
mV
UNITS
kΩ
MAX1953/MAX1954/MAX1957
Note 1:
Specifications to -40°C are guaranteed by design and not production tested.
Note 2:
HSD and IN are externally connected for applications where V
HSD
< 5.5V.
_______________________________________________________________________________________
3
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
