User Manual

MAX1775
Dual-Output Step-Down
DC-DC Converter for PDA/Palmtop Computers
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +12V, V
MAIN
= V
INC
= V
CS-
= V
CS+
= +3.3V, V
CORE
= +1.8V, Circuit of Figure 4, T
A
-40°C to +85°C, unless otherwise noted.)
(Note 2)
PARAMETER SYMBOL CONDITIONS MIN MAX UNITS
Maximum Duty Cycle 100 %
Minimum On-Time 200 650 ns
Minimum Off-Time 200 650 ns
CORE REGULATOR
Input Voltage Range V
INC
2.6 5.5 V
V
INC
rising 2.39 2.55
INC Undervoltage Lockout
V
INC
falling 2.29 2.45
V
Core Output Voltage Adjust
Range
1.0 5.0 V
Maximum Core Load Current (Note 1) 1 A
FBC Regulation Threshold V
FBC
V
INC
= +2.5V to +5.5V, I
OUTC
= 0 to 200mA 0.97 1.03 V
FBC Input Current I
FBC
V
FBC
= +1.3V -0.1 0.1 µA
Dropout Voltage (INC to LXC) I
OUTC
= 400mA 0.2 V
LXC Leakage Current I
LXC
V
INC
= +5.5V, V
LXC
= 0 to +5.5V -10 10 µA
LXC P-Channel, N-Channel
On-Resistance
0.5 Ω
LXC P-Channel Current Limit 1200 3050 mA
LXC P-Channel Minimum
Current
100 400 mA
LXC N-Channel Valley Current 880 2450 mA
LXC N-Channel Zero-Crossing
Current
35 175 mA
Maximum Duty Cycle 100 %
Minimum On-Time 150 670 ns
Minimum Off-Time 150 670 ns
REFERENCE
Reference Voltage V
REF
1.22 1.27 V
Reference Load Regulation I
REF
= 0 to 50µA 10 mV
Reference Line Regulation
V
CS-
= +2.5V to +5.5V,
I
REF
= 50µA
5mV
Reference Sink Current I
REF
10 µA
CVL, CVH REGULATORS
CVL Output Voltage V
CVL
I
CVL
= 50mA, V
IN
= +2.7V, V
CS-
= 0 2.6 3.1 V
V
IN
= +4V, I
CVH
= 25mA V
IN
- 2.8
CVH Output Voltage V
CVH
V
IN
= +12V, I
CVH
= 50mA V
IN
- 3.7
V
V
CVL
rising 2.40 2.55
CVL Undervoltage Lockout
V
CVL
falling 2.30 2.45
V