MAX1631EAI+T Maxim Integrated Products, MAX1631EAI+T Datasheet - Page 7

• Manufacturer Part Number: MAX1631EAI+T
• Description: IC PS CTRLR FOR NOTEBOOKS 28SSOP
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX1631EAI+T

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 3.3V, 5V, Adj
• Current - Output: 4A
• Frequency - Switching: 200kHz, 300kHz
• Voltage - Input: 4.2 ~ 30 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP
• Power - Output: 762mW
• Output Voltage: 2.5 V to 5.5 V, 3.3 V, 5 V
• Input Voltage: 4.2 V to 30 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

_________________________________________________Pin Description (continued)
PIN
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
5
6
7
8
9
(MAX1630/
(MAX1631/
MAX1634)
TIME/ON5
RUN/ON3
32/33/35)
SECFB
RESET
NAME
PGND
SHDN
SYNC
CSH5
CSL5
BST5
BST3
GND
SKIP
SEQ
DH5
DH3
V
REF
DL5
DL3
FB5
LX5
LX3
V+
VL
DD
_______________________________________________________________________________________
Multi-Output, Low-Noise Power-Supply
Supply Voltage Input for the 12OUT Linear Regulator. Also connects to an internal resistor divider for
secondary winding feedback, and to an 18V overvoltage shunt regulator clamp.
Secondary Winding Feedback Input. Normally connected to a resistor divider from an auxiliary output.
SECFB regulates at V
used.
Oscillator Synchronization and Frequency Select. Tie to VL for 300kHz operation; tie to GND for 200kHz
operation. Can be driven at 240kHz to 350kHz for external synchronization.
Dual-Purpose Timing Capacitor Pin and ON/OFF Control Input. See Power-Up Sequencing and
ON/
Low-Noise Analog Ground and Feedback Reference Point
2.5V Reference Voltage Output. Bypass to GND with 1µF minimum.
Logic-Control Input that disables Idle Mode when high. Connect to GND for normal use.
Active-Low Timed Reset Output. RESET swings GND to VL. Goes high after a fixed 32,000 clock-cycle
delay following power-up.
Feedback Input for the 5V SMPS; regulates at FB5 = REF (approx. 2.5V) in adjustable mode. FB5 is a
Dual Mode input that also selects the 5V fixed output voltage setting when tied to GND. Connect FB5 to
a resistor divider for adjustable-output mode.
Current-Sense Input for the 5V SMPS. Also serves as the feedback input in fixed-output mode, and as
the bootstrap supply input when the voltage on CSL5/VL is > 4.5V.
Current-Sense Input for the 5V SMPS. Current-limit level is 100mV referred to CSL5.
Pin-Strap Input that selects the SMPS power-up sequence:
Gate-Drive Output for the 5V, high-side N-channel switch. DH5 is a floating driver output that swings
from LX5 to BST5, riding on the LX5 switching node voltage.
Switching Node (inductor) Connection. Can swing 2V below ground without hazard.
Boost capacitor connection for high-side gate drive (0.1µF)
Gate-Drive Output for the low-side synchronous-rectifier MOSFET. Swings 0V to VL.
Power Ground
5V Internal Linear-Regulator Output. VL is also the supply voltage rail for the chip. After the 5V SMPS
output has reached +4.5V (typical), VL automatically switches to the output voltage via CSL5 for boot-
strapping. Bypass to GND with 4.7µF. VL supplies up to 25mA for external loads.
Battery Voltage Input, +4.2V to +30V. Bypass V+ to PGND close to the IC with a 0.22µF capacitor.
Connects to a linear regulator that powers VL.
Shutdown Control Input, active low. Logic threshold is set at approximately 1V. For automatic start-up,
connect SHDN to V+ through a 220kΩ resistor and bypass SHDN to GND with a 0.01µF capacitor.
Gate-Drive Output for the low-side synchronous-rectifier MOSFET. Swings 0V to VL.
Boost Capacitor Connection for high-side gate drive (0.1µF)
Switching Node (inductor) Connection. Can swing 2V below ground without hazard.
Gate-Drive Output for the 3.3V, high-side N-channel switch. DH3 is a floating driver output that swings
from LX3 to BST3, riding on the LX3 switching node voltage.
ON/OFF Control Input. See Power-Up Sequencing and ON/ OFF Controls section.
OFF Controls section.
Controllers for Notebook Computers
SEQ = GND: 5V before 3.3V, RESET output determined by both outputs
SEQ = REF: Separate ON3/ON5 controls, RESET output determined by 3.3V output
SEQ = VL: 3.3V before 5V, RESET output determined by both outputs
SECFB
= 2.5V (see Secondary Feedback Regulation Loop section). Tie to VL if not
FUNCTION
7