Max1510 low-voltage ddr linear regulator, Applications information – Rainbow Electronics MAX1510 User Manual
Page 10
MAX1510
Low-Voltage DDR Linear Regulator
10
______________________________________________________________________________________
Power-Good (PGOOD)
The MAX1510 provides an open-drain PGOOD output
that goes high 2ms (typ) after the output initially reach-
es regulation during startup. PGOOD transitions low
10µs after the output goes out of regulation by
±150mV,
or when the device enters shutdown. Connect a pullup
resistor from PGOOD to V
CC
for a logic-level output.
Use a 100k
Ω resistor to minimize current consumption.
Applications Information
Dynamic Output-Voltage Transitions
By changing the voltage at REFIN, the MAX1510 can
be used in applications that require dynamic output-
voltage changes between two set points (graphics
processors). Figure 4 shows a dynamically adjustable
resistive voltage-divider network at REFIN. Using an
external signal MOSFET, a resistor can be switched in
and out of the REFIN resistor-divider, changing the volt-
age at REFIN. The two output voltages are determined
by the following equations:
V
V
R
R
R
V
V
R
R
R
R
R
OUT LOW
REF
OUT HIGH
REF
(
)
(
)
=
+
=
+
(
)
+
+
(
)
2
1
2
2
3
1
2
3
MAX1510
REFIN
R2
R1
C
REFIN
R3
REFERENCE
VOLTAGE
(V
REF
)
V
OUT(HIGH)
(R2 + R3)
R1 + (R2 + R3)
V
OUT(LOW)
V
OUT(HIGH)
=
R2
R1 + R2
V
OUT(LOW)
= V
REF
V
REF
( )
Figure 4. Dynamic Output-Voltage Change
Figure 3. MAX1510 PGOOD and Soft-Start Waveforms
POWER-GOOD
WINDOW
CURRENT LIMIT
OUT
PGOOD
10
µs
PROPAGATION
DELAY
2ms STARTUP
DELAY
10
µs
PROPAGATION
DELAY
200
µs
OUTPUT OVERLOAD
CONDITION
SHDN