Typical operating characteristics, Electrical characteristics (continued) – Rainbow Electronics MAX1845 User Manual
Page 6
MAX1845
Dual, High-Efficiency, Step-Down
Controller with Accurate Current Limit
6
_______________________________________________________________________________________
0
0.01
10
1
0.1
300
350
400
200
250
100
150
50
MAX1845 toc01
LOAD CURRENT (A)
FREQUENCY (kHz)
FREQUENCY vs. LOAD CURRENT
OUT1, SKIP = V
CC
OUT2, SKIP = V
CC
OUT1, SKIP = GND
OUT2, SKIP = GND
0
50
100
150
200
250
300
350
400
4
8
12
16
20
21
MAX1845 toc02
INPUT VOLTAGE (V)
FREQUENCY (kHz)
FREQUENCY vs. INPUT VOLTAGE
(TON = FLOAT, SKIP = V
CC
)
OUT1
OUT2
I
OUT1
= 8A
I
OUT2
= 4A
__________________________________________Typical Operating Characteristics
(Circuit of Figure 1, components from Table 1, V
IN
= 15V, SKIP = GND, TON = unconnected, T
A
= +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DD
= V
CC
= 5V, SKIP = GND, V+ = 15V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 1)
Note 1: Specifications to -40°C are guaranteed by design, not production tested.
Note 2: When the inductor is in continuous conduction, the output voltage will have a DC regulation level higher than the error compara-
tor threshold by 50% of the output voltage ripple. In discontinuous conduction (SKIP = GND, light load), the output voltage will
have a DC regulation higher than the error-comparator threshold by approximately 1.5% due to slope compensation.
Note 3: On-time and off-time specifications are measured from 50% point to 50% point at DH_ with LX_ = GND, BST_ = 5V, and a
250pF capacitor connected from DH_ to LX_. Actual in-circuit times may differ due to MOSFET switching speeds.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
GND - V
CS
, V
ILIM
_ = 0.5V
35
65
Current-Limit Threshold
(Adjustable)
GND - V
CS
, V
ILIM
_ = 1V
80
120
mV
V
CC
Undervoltage Lockout
Threshold
Rising edge, hysteresis = 20mV, PWMs
disabled below this level
4.05
4.4
V
ON_, SKIP
2.4
Logic Input High Voltage
V
IH
UVP
V
CC
-
0.4
V
ON_, SKIP
0.8
Logic Input Low Voltage
V
IL
UVP
0.05
V
TON (GND or V
CC
)
-3
3
Logic Input Current
ON_, SKIP, UVP
-1
1
µA