MAX1510 Datasheet, PDF (7/13 Pages) Maxim Integrated Products – Low-Voltage DDR Linear Regulator

Low-Voltage DDR Linear Regulator
Pin Description
PIN
NAME
FUNCTION
1
REFOUT ^{Buffered Reference Output. The output of the unity-gain reference input buffer sources and sinks over}
5mA. Bypass REFOUT to AGND with a 0.33µF or greater ceramic capacitor.
2
V_CC
Analog Supply Input. Connect to the system supply voltage (+3.3V). Bypass V_CC to AGND with a 1µF or
greater ceramic capacitor.
3
AGND Analog Ground. Connect the backside pad to AGND.
4
REFIN
External Reference Input. REFIN sets the output regulation voltage (V_OUTS = V_REFIN).
Open-Drain Power-Good Output. PGOOD is low when the output voltage is more than 150mV (typ) above
5
PGOOD or below the regulation point, during soft-start, and when shut down. 2ms after the output reaches the
regulation voltage during startup, PGOOD becomes high impedance.
Output Sense Input. The OUTS regulation level is set by the voltage at REFIN. Connect OUTS to the
6
OUTS
remote DDR termination bypass capacitors. OUTS is internally connected to OUT through a 12kΩ
resistor.
7
SHDN
Shutdown Control Input. Connect to V_CC for normal operation. Connect to analog ground to shut down the
linear regulator. The reference buffer remains active in shutdown.
8
PGND Power Ground. Internally connected to the output sink MOSFET.
9
OUT
Output of the Linear Regulator
10
IN
Power Input. Internally connected to the output source MOSFET.
Detailed Description
The MAX1510 is a low-voltage, low-dropout DDR termi-
nation linear regulator with an external bias supply
input and a buffered reference output (see Figures 1
and 2). V_CC is powered by a 2.7V to 3.6V supply that is
commonly available in laptop and desktop computers.
The 3.3V bias supply drives the gate of the internal
pass transistor, while a lower voltage input at the drain
of the transistor (IN) is regulated to provide V_OUT. By
using separate bias and power inputs, the MAX1510
can drive an n-channel high-side MOSFET and use a
lower input voltage to provide better efficiency.
The MAX1510 regulates its output voltage to the volt-
age at REFIN. When used in DDR applications as a
termination supply, the MAX1510 delivers 1.25V or
0.9V at 3A peak (typ) from an input voltage of 1.1V to
3.6V. The MAX1510 sinks up to 3A peak (typ) as
required in a termination supply. The MAX1510 pro-
vides shoot-through protection, ensuring that the
source and sink MOSFETs do not conduct at the same
time, yet produces a fast source-to-sink load transient.
V_IN =
1.1V TO 3.6V
C_IN2
10µF
3.3V BIAS
SUPPLY
R3
100kΩ
POWER-GOOD
C1
1.0µF
OFF
V_DDQ
ON
R1
10kΩ
R2
10kΩ
C_REFIN
1000pF
V_OUT = V_TT = V_DDQ / 2
IN
OUT
C_OUT1
100µF
MAX1510
V_CC
PGND
AGND
PGOOD
OUTS
SHDN
REFIN
REFOUT
V_REFOUT = V_TTR
C_REFOUT
0.33µF
Figure 1. Standard Application Circuit
_______________________________________________________________________________________ 7