High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
MAX1710/MAX1711
V
BATT
4.5V TO 28V
+5V
BIAS SUPPLY
C5
1µF
R1
20Ω
C6
1µF
C1 3 x 10µF/30V
7
V
CC
1
ON/OFF
CONTROL
LOW-NOISE
CONTROL
2
21
20
19
DAC
INPUTS
18
17
16
8
C4
1µF
C3
470pF
9
5
10
V+
SHDN
SKIP
D0
D1
D2
D3
D4**
TON
REF
CC
GND
12
FB
FBS
GNDS
3
4
11
+5V
R2
100k
OVP* PGOOD
16
POWER-GOOD
INDICATOR
R4
1k
Q1 = IRF7807
Q2 = IRF7805
D1, D3 = MBRS130T3 (OPTIONAL)
C1 = Sanyo OS-CON (30SC10M)
V
DD
BST
DH
22
24
C7
0.1µF
PANASONIC
ETQP6F2R0HFA
Q1
L1
2µH
C2
3 x 470µF
KEMET T510
Q2
D1
15
D2
CMPSH-3
MAX1710
MAX1711
LX
DL
23
13
14
V
OUT
1.25V TO 2V AT 7A (MAX1710)
0.925V TO 2V AT 7A (MAX1711)
D3
(OPTIONAL OVP
REVERSE-POLARITY
CLAMP)
PGND
ILIM
TO V
CC
6
* MAX1710 ONLY
** MAX1711 ONLY
R3
(OPTIONAL)
Figure 1. Standard Application Circuit
while also avoiding the problems caused by widely vary-
ing switching frequencies in conventional constant-on-
time and constant-off-time PWM schemes.
+5V Bias Supply (V
CC
and V
DD
)
The MAX1710/MAX1711 requires an external +5V bias
supply in addition to the battery. Typically, this +5V bias
supply is the notebook’s 95% efficient 5V system supply.
Keeping the bias supply external to the IC improves effi-
ciency and eliminates the cost associated with the +5V
linear regulator that would otherwise be needed to sup-
ply the PWM circuit and gate drivers. If stand-alone
10
capability is needed, the +5V supply can be generated
with an external linear regulator such as the MAX1615.
The battery and +5V bias inputs can be tied together if
the input source is a fixed 4.5V to 5.5V supply. If the +5V
bias supply is powered up prior to the battery supply, the
enable signal (SHDN) must be delayed until the battery
voltage is present in order to ensure start-up. The +5V
bias supply must provide V
CC
and gate-drive power, so
the maximum current drawn is:
I
BIAS
= I
CC
+ f
·
(Q
G1
+ Q
G2
) = 15mA to 30mA (typ)
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
