Datasheet

PIN
MAX1714
High-Speed Step-Down Controller
for Notebook Computers
8 _______________________________________________________________________________________
Pin Description
Analog and Power Ground. AGND and PGND connect together internally.GND–
No Connection. These pins are not connected to any internal circuitry. Connect N.C. pins
to the ground plane to enhance thermal conductivity.
N.C.
2, 9,
11
Power-Good Open-Drain Output. PGOOD is low when the output voltage is more than 6%
below the normal regulation point or during soft-start. PGOOD is high impedance when
the output is in regulation and the soft-start circuit has terminated.
PGOOD10
High-Side Gate Driver Output. Swings from LX to BST.DH1
Current-Limit Threshold Adjustment. Connect ILIM to V
CC
for 100mV current-limit threshold.
For an adjustable threshold, connect an external voltage source to ILIM, or use a two-resis-
tor divider from REF to AGND. The external adjustment range of 0.5V to 2.0V corresponds to
a current-limit threshold of 50mV to 200mV.
ILIM6
+2.0V Reference Voltage Output. Bypass to AGND with 0.22µF (minimum) capacitor. Can
supply 50µA for external loads.
REF7
Analog Ground.AGND8
Shutdown Control Input. Drive SHDN to AGND to force the MAX1714 into shutdown. Drive
or connect to V
CC
for normal operation. A rising edge on SHDN clears the fault latch.
SHDN
3
Feedback Input. Connect to AGND for a +2.5V fixed output or to V
CC
for a +3.3V fixed
output, or connect FB to a resistor divider from OUT for an adjustable output.
FB4
PIN
Output Voltage Connection. Connect directly to the junction of the external and output fil-
ter capacitors. OUT senses the output voltage to determine the on-time and also serves
as the feedback input in fixed-output modes.
OUT5
FUNCTIONNAME
Low-Side Gate-Driver Output. Swings from PGND to V
DD
. DL13
Supply Input for the DL Gate Drive. Connect to the system supply voltage, +4.5V to +5.5V.
Bypass to PGND with a 1µF (min) ceramic capacitor.
V
DD
14
Analog-Supply Input. Connect to the system supply voltage, +4.5V to +5.5V, with a series
20Ω resistor. Bypass to AGND with a 1µF (min) ceramic capacitor.
V
CC
15
On-Time Selection-Control Input. This is a four-level input used to determine DH on-time.
Connect to AGND, REF, or V
CC
, or leave TON unconnected to set the following switching
frequencies: AGND = 600kHz, REF = 450kHz, floating = 300kHz, and V
CC
= 200kHz.
TON16
Battery Voltage Sense Connection. Connect to input power source. V+ is used only to set
the PWM one-shot timing.
V+17
Pulse-Skipping Control Input. Connect to V
CC
for low-noise forced-PWM mode. Connect
to AGND to enable pulse-skipping operation.
SKIP
18
Boost Flying-Capacitor Connection. Connect to an external capacitor and diode according
to the Standard Application Circuit (Figure 1). See MOSFET Gate Drivers (DH, DL) section.
BST19
External Inductor Connection. Connect LX to the switched side of the inductor. LX serves
as the lower supply rail for the DH high-side gate driver. LX is also the positive input to the
current-limit comparator.
LX20
8
–
7
1
5
6
–
2
3
4
9
10
11
12
13
14
15
16
Power Ground. Connect directly to the low-side MOSFET’s source. Serves as the negative
input of the current-limit comparator.
PGND12 –
MAX1714A MAX1714B