MAX1711 Maxim, MAX1711 Datasheet - Page 8

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

(7A CPU supply circuit of Figure 1, T
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
8
_____________________________Typical Operating Characteristics (continued)
PIN
A
B
C
1
2
3
4
5
6
7
8
9
_______________________________________________________________________________________
V
A = V
B = V
C = INDUCTOR CURRENT, 5A/div
OUT
OUTPUT OVERLOAD WAVEFORM
IN
OUT
= 1.6V
, AC COUPLED, 2V/div
, 0.5V/div
NAME
SHDN
TON
FBS
ILIM
V
REF
CC
CC
FB
CC
50 s/div
Battery Voltage Sense Connection. V+ is used only for PWM one-shot timing. DH on-time is inversely propor-
tional to V+ input voltage over a range of 2V to 28V.
Shutdown Control Input, active low. SHDN cannot withstand the battery voltage. In shutdown mode, DL is
forced to V
Fast Feedback Input, normally connected to V
ly at the power supply. An external resistor-divider can optionally set the output voltage.
Feedback Remote-Sense Input, normally connected to V
the integrator that fine-tunes the DC output voltage. Tie FBS to V
Tie FBS to FB (or disable the integrators) when externally adjusting the output voltage with a resistor-divider.
Integrator Capacitor Connection. Connect a 100pF to 1000pF (470pF typical) capacitor to GND to set the
integration time constant.
Current-Limit Threshold Adjustment. Connects to an external resistor to GND. The LX-PGND current-limit
threshold defaults to +100mV if ILIM is tied to V
ILIM. In adjustable mode the threshold is V
Analog Supply Voltage Input for PWM Core, 4.5V to 5.5V. Bypass V
capacitor.
On-Time Selection Control Input. This is a four-level input that sets the K factor to determine DH on-time.
GND = 550kHz, REF = 400kHz, open = 300kHz, V
2.0V Reference Output. Bypass REF to GND with a 0.22µF minimum capacitor. REF can source 50µA for
external loads. Loading REF degrades FB accuracy according to the REF load-regulation error
(see Electrical Characteristics ).
DD
A
in order to enforce overvoltage protection, even when powered down (unless OVP is high).
= +25°C, unless otherwise noted.)
C
A
B
L = 0.7 H, V
A = V
B = INDUCTOR CURRENT, 5A/div
C = DL, 5V/div
CERAMIC C
OUT
LOAD-TRANSIENT RESPONSE
, AC COUPLED, 100mV/div
OUT
OUT
= 1.6V, V
5 s/div
TH
IN
= R
OUT
= 15V, C
CC
FUNCTION
LIM
. FB is connected to the bulk output filter capacitors local-
. The current-limit threshold is 1/10 of the voltage forced at
CC
OUT
·
5µA/10.
= 200kHz.
= 47 F (x4), f = 550kHz
OUT
directly at the load. FBS internally connects to
CC
CC
to disable all three integrator amplifiers.
to GND with a 0.1µF minimum
C
D
A
B
V
A = V
B = INDUCTOR CURRENT, 5A/div
C = SHDN, 2V/div
D = DL, 5V/div
IN
= 15V, V
OUT
Pin Description
, 0.5V/div
SHUTDOWN WAVEFORM
0
= 1.6V, I
5 s/div
0
= 7A