MAX1711 Maxim, MAX1711 Datasheet - Page 11

• Manufacturer Part Number: MAX1711
• Description: High-Speed / Digitally Adjusted Step-Down Controllers for Notebook CPUs
• Manufacturer: Maxim

Figure 2. MAX1710 Functional Diagram
where I
and Q
gate-charge specification limits at V
The QUICK-PWM control architecture is an almost fixed-
frequency, constant-on-time current-mode type with volt-
age feed-forward (Figure 2). This architecture relies on
V
BATT
2V TO 28V
G1
CC
Free-Running, Constant-On-Time PWM
and Q
FBS
PGOOD
is 600µA typical, f is the switching frequency,
TON
OVP
SKIP
SHDN
CC
GNDS
Controller with Input Feed-Forward
Step-Down Controllers for Notebook CPUs
-5%
REF
TRIG
g
m
G2
COMPUTE
______________________________________________________________________________________
ON-TIME
1-SHOT
TON
TON
are the MOSFET data sheet total
V+
OVP/UVLO
g
m
LATCH
Q
FB
+12%
FROM
REF
REF
D/A
S1
70k
Q
g
S2
m
-30%
GS
REF
TIMER
ERROR
AMP
10k
= 5V.
REF
High-Speed, Digitally Adjusted
Q
1-SHOT
S
R
TOFF
Q
TRIG
D0
D/A CONVERTER
S
R
D1
R-2R
CURRENT
Q
V
LIMIT
CC
D2
R
LIM
the filter capacitor’s ESR to act as the current-sense
resistor, so the output ripple voltage provides the PWM
ramp signal. The control algorithm is simple: the high-
side switch on-time is determined solely by a one-shot
whose period is inversely proportional to input voltage
and directly proportional to output voltage. Another one-
shot sets a minimum off-time (400ns typical). The on-time
one-shot is triggered if the error comparator is low, the
5 A
D3
I
LIM
CHIP SUPPLY
MAX1710
ZERO CROSSING
REF
2V
PGND
GND
BST
V
V
REF
DH
DL
LX
DD
FB
CC
+5V
+5V
+5V
OUTPUT
11