Rainbow Electronics MAX1771 - Manual (Page 6)

MAX1771
12V or Adjustable, High-Efficiency,
Low I
Q , Step-Up DC-DC Controller
6 _______________________________________________________________________________________
2ms/div
I OUT = 500mA, V IN = 5V
A: SHDN, 5V/div
B: V
OUT
, 5V/div
A
B
0V
0V
ENTERING/EXITING SHUTDOWN
5V
Pin Description
Typical Operating Characteristics (continued)
(Circuit of Figure 2a, T
A
= +25°C, unless otherwise noted.)
PIN NAME FUNCTION
1 EXT Gate Drive for External N-Channel Power Transistor
2 V+
3 FB
4 SHDN
5 REF
6 AGND Analog Ground
7 GND High-Current Ground Return for the Output Driver
8 CS
Power-Supply Input. Also acts as a voltage-sense point when in bootstrapped mode.
Feedback Input for Adjustable-Output Operation. Connect to ground for fixed-output operation.
Use a resistor divider network to adjust the output voltage. See Setting the Output Voltage section.
Active-High TTL/CMOS Logic-Level Shutdown Input. In shutdown mode, V OUT is a diode drop
below V+ (due to the DC path from V+ to the output) and the supply current drops to 5µA
maximum. Connect to ground for normal operation.
1.5V Reference Output that can source 100µA for external loads. Bypass to GND with 0.1µF.
The reference is disabled in shutdown.
Positive Input to the Current-Sense Amplifier. Connect the current-sense resistor between CS
and GND.