MAX1692
Low-Noise, 5.5V-Input,
PWM Step-Down Regulator
_______________________________________________________________________________________ 3
Note 1: Guaranteed by minimum and maximum duty-factor tests.
Note 2: The following equation can be used to calculate FB accuracy for output voltages other than 1.232V:
(see Feedback Voltage vs. Load Current)
V
FB
= V
FB (NOMINAL)
- (Line Reg) (V
OUT
/ V
IN
- 0.23) / 0.77 - (Load Reg)(I
OUT
+ 0.5 · I
RIPPLE
) / I
MAX
where: Line Reg = the line regulation
Load Reg = the load regulation
I
RIPPLE
= (1- V
OUT
/ V
IN
) · V
OUT
/ (f
OSC
· L) where L is the inductor value
I
MAX
= 250mA (LIM = GND) or 600mA (LIM = IN)
Note 3: Specifications to -40°C are guaranteed by design, not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +3.6V, SYNC/PWM = GND, V
LIM
= 3.6V, SHDN = IN, circuit of Figure 2; T
A
= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
High or low
0 ≤ I
REF
≤ 50µA
SHDN, SYNC/PWM, LIM
CONDITIONS
ns500
SYNC/PWM Minimum Pulse Width
mV3 15Reference Load Regulation
µA-1 0.1 1Logic Input Current
UNITSMIN TYP MAXSYMBOLPARAMETER
(Note 1)
FB = OUT, V
IN
= V
LIM
= 2.7V to 5.5V,
I
OUT
= 0
SYNC/PWM = GND, LX = unconnected,
V
FB
= 1.4V
FB = OUT, V
IN
= V
LIM
= 5.5V, I
OUT
= 0
(duty cycle = 23%) (Note 2)
V
FB
=1.4V
LIM = IN
CONDITIONS
VREF V
IN
Output Adjustment Range
1.213 1.285
V2.7 5.5V
IN
Input Voltage Range
µA140Quiescent Current
V1.213 1.285V
FB
Feedback Voltage
nA-50 50I
FB
FB Input Current
A
0.7 1.6
P-Channel Current-Limit
Threshold
mA
N-Channel Current-Limit
Threshold
UNITSMIN MAXSYMBOLPARAMETER
ELECTRICAL CHARACTERISTICS
(V
IN
= +3.6V, SYNC/PWM = GND, V
LIM
= 3.6V, SHDN = IN, circuit of Figure 2, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 3)
LIM = GND
SYNC/PWM = IN, FB = REF -15 110
SHDN = LX = GND, includes LX leakage current
µA10Shutdown Supply Current
kHz630 840f
OSC
Oscillator Frequency
I
REF
= 0 V1.230 1.268V
REF
Reference Output Voltage
V
IN
rising, typical hysteresis is 85mV V2.3 2.5UVLO
Undervoltage Lockout
Threshold
SHDN, SYNC/PWM, LIM
V2V
IH
Logic Input High
SHDN, SYNC/PWM, LIM
V0.4V
IL
Logic Input Low
SHDN, SYNC/PWM, LIM
µA-1 1Logic Input Current
0.3 0.9
SHDN, SYNC/PWM, LIM
V0.4V
IL
Logic Input Low
V
IN
rising, typical hysteresis is 85mV V2.3 2.4 2.5UVLOUndervoltage Lockout Threshold
SHDN, SYNC/PWM, LIM
V2V
IH
Logic Input High
FB = OUT, V
IN
= 2.7V to 5.5V,
I
OUT
= 0 to 600mA, LIM = IN or
I
OUT
= 0 to 250mA, LIM = GND
V
1.185 1.285
V
OUT
Output Voltage
(24 Seiten)
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