ML4901 Datasheet, PDF (1/8 Pages) Micro Linear Corporation – High Current Synchronous Buck Controller

April 1997
PRELIMINARY
ML4901
High Current Synchronous Buck Controller
GENERAL DESCRIPTION
The ML4901 high current synchronous buck controller has
been designed to provide high efficiency DC/DC
conversion for next generation processors such as the
Pentium^® Pro from Intel^®.
The ML4901 controller, when combined with 2 external
MOSFETs, generates output voltages between 2.1V and
3.5V from a 12V supply. The output voltage is selected via
an internal 4-bit DAC. Output currents in excess of 14A
can be attained at efficiencies greater than 90%.
The ML4901 can be enabled/disabled via the SHDN pin.
While disabled, the output of the regulator is completely
isolated from the circuit’s input supply. The ML4901
employs fixed-frequency PWM control combined with a
dual mode control loop to provide excellent load transient
response.
FEATURES
s Designed to meet Pentium^® Pro power supply
requirements
s DC regulation to +1% maximum
s Proprietary circuitry provides transient response of +5%
maximum over 300mA to 14A load range
s Programmable output voltage (2.1V to 3.5V) is set by an
onboard 4-bit DAC
s Synchronous buck topology for maximum power
conversion efficiency
s Fixed frequency operation for easier system integration
s Integrated antishoot-through logic, short circuit
protection, and UV lockout
s Shutdown control provides load isolation
BLOCK DIAGRAM (Pin Configuration Shown for 16-Pin SOIC Version)
VDD
15
+
10.4V ^–
PROTECT
16
+
4.4V ^–
UVLO
35µA
SHDN
5
D0
1
D1
2
D2
3
D3
4
4 BIT DAC
VDAC
VDAC + 3%
+
–
VFB
+
VDAC - 3%
–
CONTROL
LOGIC
+
–
200kHz
VDAC + 10%
+
VDAC + 3%
–
VFB
+
VDAC - 10%
–
VDAC - 3%
P DRV
14
N DRV
13
PWR GND
12
COMP
11
VFB
9
VDAC
-95mV _ISENSE
10
PWR GOOD
6
3.5V
REFERENCE
VREF
7
GND
8
1