Rainbow Electronics MAX684 - Manual (Page 5)

MAX682/MAX683/MAX684
3.3V-Input to Regulated 5V-Output
Charge Pumps
_______________________________________________________________________________________ 5
2ms/div
LOAD-TRANSIENT RESPONSE
MAX682 TOC19
A
B
A: LOAD CURRENT: I LOAD = 5mA TO 250mA, 500mA/div
B: OUTPUT VOLTAGE: SKIP = HIGH, I
SHDN
= 22 µ A,
100mV/div, MAX682
100 µ s/div
SHUTDOWN TIMING
MAX682 TOC18
A
B
A: OUTPUT VOLTAGE: SKIP = HIGH, R
L
= 5V / I
MAX
, 2V/div
B: SHDN VOLTAGE: 1V/div
2ms/div
LINE-TRANSIENT RESPONSE
MAX682 TOC20
A
B
A: INPUT VOLTAGE: V IN = 3.1V TO 3.6V, 500mV/div
B: OUTPUT VOLTAGE: SKIP = HIGH, I
SHDN
= 22 µ A,
I LOAD = 250mA, 50mV/div, MAX682
Typical Operating Characteristics (continued)
(Circuit of Figure 5, V IN = 3.3V, component values from Tables 2 and 3, T A = +25°C, unless otherwise noted.)
Pin Description
NAME FUNCTION
1 SKIP
When SKIP = low, the regulator operates in low-quiescent-current skip mode. When SKIP = high, the
regulator operates in constant-frequency mode, minimizing output ripple and noise. SKIP must be tied
high for input voltages above 3.6V.
2 SHDN
Shutdown Input. Drive SHDN through an external resistor. When SHDN = low, the device turns off. When
current is sourced into SHDN through R
EXT , the device activates, and the SHDN pin input current sets the
oscillator’s switching frequency. R EXT (k
Ω
) = 45000 (V IN - 0.69V) / f OSC (kHz).
PIN
3 IN
Input Supply Pin. Can range from 2.7V to 5.5V for SKIP = high, and 2.7V to 3.6V for SKIP = low. Bypass to
PGND with a suitable value capacitor (see
Capacitor Selection section).
4 GND Ground Pin. Connect to PGND through a short trace.
8 OUT Fixed 5V Power Output. Bypass to PGND with output filter capacitor.
7 CXP Positive Terminal of the Charge-Pump Transfer Capacitor
6 CXN Negative Terminal of the Charge-Pump Transfer Capacitor
5 PGND Power Ground Pin