MAX649 Maxim, MAX649 Datasheet - Page 6

• Manufacturer Part Number: MAX649
• Description: 5V/3.3V/3V or Adjustable / High-Efficiency /
• Manufacturer: Maxim

5V/3.3V/3V or Adjustable, High-Efficiency,
Low I
6
_____________________________Typical Operating Characteristics (continued)
______________________________________________________________Pin Description
PIN
1
2
3
4
5
6
7
8
_______________________________________________________________________________________
I
A: INPUT VOLTAGE (7V & 12V), 5V/div
B: 5V OUT, AC COUPLED, 100mV/div
LOAD
NAME
SHDN
GND
OUT
REF
EXT
V+
CS
FB
= 1A
Q
LINE-TRANSIENT RESPONSE
, Step-Down DC-DC Controllers
Sense input for fixed 5V, 3.3V, or 3V output operation. OUT is internally connected to the on-chip voltage divider.
Although it is connected to the output of the circuit, the OUT pin does not supply current.
Feedback input. Connect to GND for fixed-output operation. Connect a resistor divider between OUT, FB,
and GND for adjustable-output operation. See Setting the Output Voltage section.
Active-high TTL/CMOS logic-level input. Part is placed in shutdown when SHDN is driven high. In shutdown mode,
the reference and the external MOSFET are turned off, and OUT = 0V. Connect to GND for normal operation.
1.5V reference output that can source 100µA. Bypass with 0.1µF.
Positive power-supply input
Current-sense input. Connect current-sense resistor between V+ and CS. When the voltage across the
resistor equals the current-limit trip level, the external MOSFET is turned off.
Gate drive for external P-channel MOSFET. EXT swings between V+ and GND.
Ground
MAX649
250 s/div
I
A: SHDN INPUT VOLTAGE (0V & 5V), 2V/div
B: 5V OUTPUT VOLTAGE, 2V/div
LOAD
A
B
= 1A
SHUTDOWN RESPONSE TIME
MAX649
1ms/div
FUNCTION
A: LOAD CURRENT (100mA & 1A), 500mA/div
B: 5V OUTPUT VOLTAGE, AC COUPLED, 50mV/div
LOAD-TRANSIENT RESPONSE
A
B
MAX649
250 s/div
A
B