MAX1672 Datasheet, PDF (5/12 Pages) Maxim Integrated Products – Step-Up/Down DC-DC Converter in QSOP Package

Step-Up/Down DC-DC Converter
in QSOP Package
_____________________________Typical Operating Characteristics (continued)
(T_A = +25°C, unless otherwise noted.)
OUTPUT RIPPLE (HEAVY LOAD)
MAX1672-13
START-UP DELAY
MAX1672-14
TURN-OFF DELAY
MAX1672-15
A
A
B
10µs/div
A: V_OUT = 5V (20mV/div, AC COUPLED)
B: I_L1 (500mA /div) (V_IN = 2.7V, I_OUT = 250mA)
B
50µs/div
A: V_OUT = (2V/div)
B: ONB (2V/div) (V_IN = 2.7V, R_LOAD = 50Ω)
A
B
200µs/div
A: V_OUT = (2V/div)
B: ONB (2V/div) (V_IN = 2.7V, R_LOAD = 50Ω)
______________________________________________________________Pin Description
PIN NAME
FUNCTION
1
LX
Inductor Connection to the Drain of the Internal N-Channel Power MOSFET
2
PGND Power Ground
3
ONB
On Control Input. When ONB = low or ONA = high, the IC is on. Connect ONB to GND for normal operation
(Table 1).
4
ONA
On Control Input. When ONA = low and ONB = high, the IC is off. Connect ONA to PS for normal operation
(Table 1).
5
3/5
Output Voltage Selection Input. Connect to PS for 3.3V output and to GND for 5V output. With V_FB > 80mV,
the state of the 3/5 pin is ignored. (Table 2).
6
PGI
Low-Battery Detector Input (1.25V threshold)
7
PGO
Low-Battery Detector Output (open drain). PGO pulls low when V_PGI is greater than 1.25V.
8
ILIM
Inductor-Current-Limit Selection Input. Connect to PS for 0.8A current limit and to GND for 0.5A current limit.
9
OUT Regulator Output. Drain of internal PFET linear regulator. Bypass with a 4.7µF capacitor to GND.
10
FB
Feedback Input. For 3.3V or 5V output, connect to GND. For adjustable output, connect to feedback resistor-
divider network. With V_FB > 70mV, the state of the 3/5 pin is ignored.
11
PS
Bootstrapped Power Supply. Output of step-up switch-mode regulator and source of internal PFET linear
regulator. The IC is powered from this pin.
12
IN
Input Voltage Sense Input. Connect to input supply.
13
REF
Reference Voltage Output. Bypass with a 0.1µF capacitor to GND.
14
GND Analog Ground
15
PGND Power Ground
16
LX
Inductor Connection to the Drain of the Internal N-Channel Power MOSFET
_______________________________________________________________________________________ 5