MAX1999EEI Maxim Integrated Products, MAX1999EEI Datasheet - Page 23

• Manufacturer Part Number: MAX1999EEI
• Description: DC/DC Switching Controllers
• Manufacturer: Maxim Integrated Products

Specifications of MAX1999EEI

• Number Of Outputs: 1
• Output Voltage: 3.3 V, 2 V to 5.5 V
• Output Current: 0.95 A
• Input Voltage: 6 V to 24 V
• Mounting Style: SMD/SMT
• Package / Case: QSOP-28
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Case: SSOP
• Dc: 07+/04+
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

in shutdown mode. When shutdown mode activates, the
reference turns off, making the threshold to exit shut-
down inaccurate. To guarantee startup, drive SHDN
above 2V (SHDN input rising-edge trip level). For auto-
matic shutdown and startup, connect SHDN to V+. If
PRO is low, both SMPS outputs are discharged to 0.3V
through a 12Ω switch before entering true shutdown.
The accurate 1V falling-edge threshold on SHDN can be
used to detect a specific analog voltage level and shut
the device down. Once in shutdown, the 1.6V rising-
edge threshold activates, providing sufficient hysteresis
for most applications. For additional hysteresis, the
undervoltage threshold can be made dependent on
REF or LDO_, which go to 0V in shutdown.
Table 3. Operating Mode Truth Table
Table 4. Power-Up Sequencing
Power-Up
Run
Overvoltage
Protection
Undervoltage
Protection
Discharge
Standby
Shutdown
Thermal Shutdown
SHDN (V)
< 1.0
> 2.4
> 2.4
> 2.4
> 2.4
> 2.4
> 2.4
MODE
Supply Controllers for Notebook Computers
High-Efficiency, Quad Output, Main Power-
______________________________________________________________________________________
V
LDO5 < UVLO threshold
SHDN = high, ON3 or ON5
enabled
Either output > 111% of
nominal level, PRO = low
Either output < 70% of
nominal after 22ms time-
out expires and output is
enabled, PRO = low
PRO is low and either
SMPS output is still high in
either standby mode or
shutdown mode
ON5, ON3 < startup
threshold, SHDN = high
SHDN = low
T
ON3
< 1.6
< 1.6
> 2.4
> 2.4
> 2.4
J
REF
X
> +160°C
(V)
CONDITION
V
ON5
< 1.6
< 1.6
> 2.4
> 2.4
> 2.4
REF
X
(V)
Transitions to discharge mode after a V+ POR and after REF becomes valid.
LDO5, LDO3, REF remain active. DL_ is active if PRO is low.
Normal operation
DL_ is forced high. LDO3, LDO5 active. Exited by a V+ POR or by toggling
SHDN, ON3, or ON5.
If PRO is low, DL_ is forced high after discharge mode terminates. LDO3,
LDO5 active. Exited by a V+ POR or by toggling SHDN, ON3, or ON5.
Discharge switch (12Ω) connects OUT_ to PGND. One output may still run
while the other is in discharge mode. Activates when LDO_ is in UVLO, or
transition to UVLO, standby, or shutdown has begun. LDO3, LDO5 active.
DL_ stays high if PRO is low. LDO3, LDO5 active.
All circuitry off
All circuitry off. Exited by V+ POR or cycling SHDN, ON3, or ON5.
LDO5
Off
On
On
On
On
On
On
ON3 and ON5 control SMPS power-up sequencing.
ON3 or ON5 rising above 2.4V enables the respective
outputs. ON3 or ON5 falling below 1.6V disables the
respective outputs.
Connecting ON3 or ON5 to REF forces the respective
outputs off while the other output is below regulation and
starts after that output regulates. The second SMPS
remains on until the first SMPS turns off, the device shuts
down, a fault occurs, or LDO5 goes into undervoltage
lockout. Both supplies begin their power-down sequence
immediately when the first supply turns off. Driving ON_
LDO3
Off
On
On
On
On
On
On
COMMENT
On/Off Controls (ON3, ON5)
Power-Up Sequencing and
SMPS is up)
On (after 3V
5V SMPS
On
On
Off
Off
Off
On
SMPS is up)
On (after 5V
3V SMPS
Off
Off
On
On
Off
On
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