Du a l-Ou t p u t P o w e r-S u p p ly
Co n t ro lle r fo r No t e b o o k Co m p u t e rs
MAX786
_______________________________________________________________________P in De s c rip t io n
PIN
1
NAME
CS3
SS3
ON3
D1
FUNCTION
Current-sense input for +3.3V; +100mV = current limit level referenced to FB3.
Soft-start input for +3.3V. Ramp time to full current limit is 1ms/nF of capacitance to GND.
ON/OFF control input disables the +3.3V PWM. Tie directly to VL for automatic start-up.
#1 level-translator/comparator noninverting input, threshold = +1.650V. Controls Q1. Tie to GND if unused.
#2 level-translator/comparator noninverting input (see D1)
2
3
4
5
D2
6
VH
External positive supply-voltage input for the level translators/comparators
#2 level-translator/comparator output. Sources 20µA from VH when D2 is high. Sinks 500µA to GND
when D2 is low, even with VH = 0V.
7
Q2
8
9
Q1
#1 level translator/comparator output (see Q2)
Low-current analog ground
GND
REF
10
3.3V reference output. Sources up to 5mA for external loads. Bypass to GND with 1µF/mA of load or
0.22µF minimum.
Oscillator control/synchronization input. Connect to VL or GND for 200kHz; connect to REF for
300kHz. For external clock synchronization in the 240kHz to 350kHz range, a high-to-low transition
causes a new cycle to start.
11
SYNC
Shutdown control input, active low. Tie to VL for automatic start-up. The 5V VL supply stays active in
shutdown, but all other circuitry is disabled. Do not force SHDN higher than VL + 0.3V.
12
SHDN
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
ON5
SS5
CS5
DH5
LX5
ON/OFF control input disables the +5V PWM supply. Tie to VL for automatic start-up.
Soft-start control input for +5V. Ramp time to full current limit is 1ms/nF of capacitance to GND.
Current-sense input for +5V; +100mV = current-limit level referenced to FB5.
Gate-drive output for the +5V high-side MOSFET
Inductor connection for the +5V supply
BST5
DL5
PGND
FB5
VL
Boost capacitor connection for the +5V supply (0.1µF)
Gate-drive output for the +5V low-side MOSFET
Power ground
Feedback and current-sense input for the +5V PWM
5V logic supply voltage for internal circuitry. VL is always on and can source 5mA for external loads.
Supply voltage input from battery, 5.5V to 30V
V+
DL3
BST3
LX3
Gate-drive output for the +3.3V low-side MOSFET
Boost capacitor connection for the +3.3V supply (0.1µF)
Inductor connection for the +3.3V supply
DH3
FB3
Gate-drive output for the +3.3V high-side MOSFET
Feedback and current-sense input for the +5V PWM
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7
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
