MAX1711 Maxim, MAX1711 Datasheet - Page 10

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

while also avoiding the problems caused by widely vary-
ing switching frequencies in conventional constant-on-
time and constant-off-time PWM schemes.
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
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
10
Figure 1. Standard Application Circuit
** MAX1711 ONLY
* MAX1710 ONLY
______________________________________________________________________________________
BIAS SUPPLY
4.5V TO 28V
V
BATT
LOW-NOISE
+5V
CONTROL
CONTROL
ON/OFF
TO V
470pF
INPUTS
1 F
DAC
C4
C3
CC
+5V Bias Supply (V
1 F
C5
21
20
19
18
17
16
10
1
2
8
9
5
V+
SHDN
SKIP
D0
D1
D2
D3
D4**
TON
REF
CC
GND
V
ILIM
CC
7
6
R3
(OPTIONAL)
MAX1710
MAX1711
OVP*
20
R1
16
PGOOD
PGND
GNDS
V
BST
FBS
DD
DH
LX
DL
FB
15
CC
23
13
14
11
12
22
24
3
4
and V
+5V
C7
0.1 F
D2
CMPSH-3
R2
100k
1 F
C6
DD
POWER-GOOD
INDICATOR
)
Q1
Q2
C1 3 x 10 F/30V
PANASONIC
ETQP6F2R0HFA
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
the maximum current drawn is:
2 H
L1
R4
1k
D1
I
BIAS
= I
CC
Q1 = IRF7807
Q2 = IRF7805
D1, D3 = MBRS130T3 (OPTIONAL)
C1 = Sanyo OS-CON (30SC10M)
+ f · (Q
C2
3 x 470 F
KEMET T510
G1
+ Q
CC
G2
) = 15mA to 30mA (typ)
and gate-drive power, so
0.925V TO 2V AT 7A (MAX1711)
1.25V TO 2V AT 7A (MAX1710)
D3
(OPTIONAL OVP
REVERSE-POLARITY
CLAMP)
V
OUT