Termination Regulator. BD3532F Datasheet
Termination Regulator for DDR-SDRAMs
BD3532F is a termination regulator that complies with
JEDEC requirements for DDR-SDRAM. This linear
power supply uses a built-in N-channel MOSFET and
high-speed OP-AMPS specially designed to provide
excellent transient response. It has a sink/source
current capability up to 3A and has a power supply
bias requirement of 5.0V for driving the N-channel
MOSFET. By employing an independent reference
voltage input (VDDQ) and a feedback pin (VTTS), this
termination regulator provides excellent output voltage
accuracy and load regulation as required by JEDEC
standards. Additionally, BD3532F has a reference
power supply output (VREF) for DDR-SDRAM or for
memory controllers. Unlike the VTT output that goes to
“Hi-Z” state, the VREF output is kept unchanged when
EN input is changed to “Low”, making this IC suitable
for DDR-SDRAM under “Self Refresh” state.
Incorporates a Push-Pull Power Supply for
Incorporates a Reference Voltage Circuit (VREF)
Incorporates an Enabler
Incorporates an Undervoltage Lockout (UVLO)
Incorporates a Thermal Shutdown Protector (TSD)
Compatible with Dual Channel (DDR-II)
Power supply for DDR I/II - SDRAM
Termination Input Voltage Range: 1.0V to 5.5V
VCC Input Voltage Range:
4.3V to 5.5V
High side FET ON-Resistance:
Low side FET ON-Resistance:
Operating Temperature Range: -40°C to +100°C
W(Typ) x D(Typ) x H(Max)
5.00mm x 6.20mm x 1.71mm
Typical Application Circuit, Block Diagram
○Product structure：Silicon monolithic integrated circuit
© 2015 ROHM Co., Ltd. All rights reserved.
○This product has no designed protection against radioactive rays
2 EN Enable input pin
3 VTTS Detector pin for termination voltage
4 VREF Reference voltage output pin
5 VDDQ Reference voltage input pin
7 VTT_IN Termination input pin
8 VTT Termination output pin
Description of Blocks
The VCC pin is for the independent power supply input that operates the internal circuit of the IC. It is the voltage at
this pin that drives the IC’s amplifier circuits. The VCC input ranges 5V and maximum current consumption is 4mA. A
bypass capacitor of 1μF or so should be connected to this pin when using the IC in an application circuit.
This is the power supply input pin for an internal voltage divider network. The voltage at VDDQ is halved by two 50kΩ
internal voltage-divider resistors and the resulting voltage serves as reference for the VTT output. Since VTT =
1/2VDDQ, the JEDEC requirement for DDR-SDRAM can be satisfied by supplying the correct voltage to VDDQ.
Noise input should be avoided at the VDDQ pin as it is also included by the voltage-divider at the output. An RC filter
consisting of a resistor and a capacitor (220Ω and 2.2μF, for instance,) may be used to reduce the noise input but
make sure that it will not significantly affect the voltage-divider’s output.
VTT_IN is the power supply input pin for the VTT output. Input voltage may range from 1.0V to 5.5V, but
consideration must be given to the current limit dictated by the ON-Resistance of the IC and to the change in allowable
loss due to input/output voltage difference.
Generally, the following voltages are supplied:
・ DDR I
Take note that a high impedance voltage input at VTT_IN may result in oscillation or degradation in ripple rejection, so
connecting a 10 μF capacitor with minimal change in capacitance to VTT_IN terminal is recommended. However, this
impedance may depend on the characteristics of the power supply input and the impedance of the PCB wiring, which
must be carefully checked before use.
BD3532F provides a constant voltage, VREF, which is independent from the VTT output and can serve as reference
input for memory controllers and DRAMs. The voltage level of VREF is kept constant even if the EN pin is at “Low”
level, making the use of this IC compatible with the “Self Refresh” state of DRAMs.
In order to stabilize the output voltage, connecting the correct combination of capacitor and resistor to VREF is
necessary. For this purpose, a combination of 1.0μF to 2.2μF ceramic capacitor, characterized by minimal variation in
capacitance, and a 0.5Ω to 2.2Ω phase compensating resistor is recommended. A 10μF ceramic or tantalum capacitor
can also be used. The maximum current capability of the VREF pin is 20mA.
VTTS is a sense pin for the load regulation of the VTT output voltage. In case the wire connecting VTT pin and the load
is too long, connecting VTTS pin to the part of the wire nearer to the load may improve load regulation.
© 2015 ROHM Co., Ltd. All rights reserved.