MAX688CPA Maxim Integrated Products, MAX688CPA Datasheet - Page 6

• Manufacturer Part Number: MAX688CPA
• Description: IC REG LINEAR LDO 3.3V FXD 8-DIP
• Manufacturer: Maxim Integrated Products

Specifications of MAX688CPA

• Regulator Topology: Positive Fixed
• Voltage - Output: 3.3V
• Voltage - Input: Up to 11V
• Voltage - Dropout (typical): 0.04V @ 200mA
• Number Of Regulators: 1
• Current - Output: 1A
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Limit (min): -

The MAX687/MAX688/MAX689 are precision low-
dropout linear regulators employing external PNP tran-
sistors to achieve a wide range of output currents at
voltages of 3.0V or 3.3V. The maximum base current
for the PNP can be limited using a resistor. Limiting the
base drive keeps high currents from being wasted
when the device is in dropout (e.g., at low input volt-
ages), and limits the regulator’s output current. The
dropout voltage is limited only by the PNP transistor’s
V
the output voltage drops 170mV below the nominal
level.
The three devices differ in their output voltages, in their
shutdown-control functions, and in PFO’s output drive
(see Table 1).
High-Accuracy, Low-Dropout
Linear Regulators
6
______________________________________________________________Pin Description
_______________Detailed Description
CE(SAT)
PIN
_______________________________________________________________________________________
1
2
2
3
4
5
6
7
8
. The Power-Fail Output (PFO) goes low when
(MAX687)
(MAX688/
MAX689)
NAME
SHDN
BASE
BLIM
GND
OUT
PFO
ON
CC
IN
Positive input voltage, 2.7V to 11.0V
ON activates the regulator when pulsed high. In order for the regulator to remain on, ON must remain high
until V
and remains latched off until ON is pulsed high. When powered up, the MAX687 does not start up until ON
is pulsed high. Connect to V
SHDN is a three-level input that controls the mode of operation. The device is on when V
The output is disabled and the supply current is reduced (I
and is fully off (I
tion is not used. PFO is low when SHDN is low (below 0.2V).
Power-Fail Output. PFO trips when V
sinks current in the MAX687, but is an open drain in the MAX688/MAX689. When shut down, PFO is always
low and sinks current. Leave PFO open if not used.
Ground
Regulator Output. MAX687/MAX688, 3.3V; MAX689, 3.0V.
Base current limit. A resistor (R
PNP transistor: I
vides current limiting without using a current-sense resistor in the collector of the external PNP, thus not
impacting dropout. Output current limiting accuracy depends on how well the external PNP beta (h
controlled. Connect to BASE if not used.
Base drive for the external PNP transistor. Current limiting is controlled using a resistor (R
between BASE and BLIM. For maximum output current, connect BASE to BLIM.
Compensation Capacitor. Connect a non-polarized capacitor (10nF to 100nF) from CC to GND.
OUT
exceeds the internal shutdown threshold voltage. The MAX687 is shut down when V
IN
BASE
< 1µA, shutdown mode) when V
≤ 0.1V / (R
IN
if not used.
B
B
) connected between BASE and BLIM sets the maximum base drive to the
+ 5Ω). This limits quiescent current rise during dropout and also pro-
OUT
is 170mV below nominal V
The MAX687’s output voltage is internally monitored; a
falling V
put falls further, the MAX687 automatically enters a low-
power shutdown mode, where the base drive to the
external PNP is cut off. PFO trips at a minimum of
110mV below the nominal V
by 2.96V. PFO is guaranteed to trip before the device
Table 1. Device Functions
FUNCTION
FUNCTION
Shutdown
Control
V
SHDN
PFO
OUT
OUT
< 0.2V. Connect SHDN to IN if the shutdown func-
IN
is signaled by PFO going low. As the out-
< 25µA, standby mode) when V
Automatic at low
Use ON to start.
Sources & Sinks
V
OUT
MAX687
. Latched.
OUT
3.3V
at I
BASE
OUT
= 1mA. PFO sources and
Open Drain
MAX688
, and shutdown occurs
External
SHDN
3.3V
SHDN
B
) connected
SHDN
OUT
> 1.25V.
Open Drain
MAX689
External
SHDN
FE
< 2.96V,
< 1.2V,
3.0V
) is