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參數(shù)資料
| 型號(hào)： | MAX6774B |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Automotive Micropower Linear Regulators with Supervisor |
| 中文描述： | 汽車微功耗線性穩(wěn)壓器的監(jiān) |
| 文件頁數(shù)： | 16/23頁 |
| 文件大?。?/td> | 309K |
| 代理商： | MAX6774B |
M
Automotive Micropower Linear Regulators
with Supervisor
16
______________________________________________________________________________________
Watchdog Timer (MAX6773/MAX6773B/
MAX6774/MAX6774B)
The MAX6773/MAX6774 include a watchdog timer that
asserts
RESET
if the watchdog input (WDI) does not
toggle within the watchdog timeout period t
WD
(1.6s
(typ) for the MAX6773/MAX6774 and 50ms (typ) for the
MAX6773B/MAX6774B).
RESET
remains low for the
reset timeout period, t
RP
. If the watchdog is not updat-
ed for lengthy periods of time, the reset output appears
as a pulse train, asserted for the reset timeout period
and deasserted for the watchdog timeout period, until
WDI is toggled again. When
RESET
asserts, it stays low
for the entire reset timeout period ignoring any WDI
transitions. To prevent the watchdog from asserting
RESET
, toggle WDI with a valid rising or falling edge
prior to t
WD
(min). The watchdog counter clears when
WDI toggles prior to t
WD
or when
RESET
asserts. The
watchdog resumes counting after
RESET
deasserts.
The watchdog timer cannot be disabled.
Thermal Protection
When the junction temperature exceeds T
J
= +160°C
(typ), an internal thermal sensor signals the shutdown
logic that turns off the pass transistor and allows the IC
to cool. The thermal sensor turns the pass transistor on
again after the IC’s junction temperature cools by 20°C
(typ), resulting in a cycled output during continuous
thermal-overload conditions. Thermal protection pro-
tects the MAX6765–MAX6774B in the event of a fault
condition. Never exceed the absolute maximum junction
temperature rating of T
J
= +150°C. See Figures 3 and 4
for the safe operating area.
Applications Information
Output Voltage Selection
The MAX6767–MAX6774B feature dual-mode operation:
these devices operate in either a preset or adjustable
voltage mode. In preset voltage mode, internal trimmed
feedback resistors set the internal linear regulator to
+1.8V, +2.5V, +3.3V, or +5V (see Table 2). Select pre-
set-voltage mode by connecting SET to ground. In
adjustable mode, select an output voltage between
+1.8V and +11V using two external resistors connected
as a voltage-divider to SET (see Figure 1). Set the output
voltage using the following equation:
V
OUT
= V
SET
(1+R1/R2)
where V
SET
= 1.233V and the recommended value for
R2 is 50k
(maximum 100k
).
RESETIN Threshold Selection
The MAX6769/MAX6770 feature an adjustable reset
threshold to monitor the voltage on RESETIN using a
resistive divider between the monitored voltage,
RESETIN and GND. See Figure 2. Use the following for-
mula to set the desired reset threshold:
V
MON
= V
TH
(1+R3/R4)
where V
TH
is 1.085V for the M/S/Y/V versions and
1.147V for L/T/Z/W versions.
MAX6769
MAX6770
RESET
RESETIN
R3
R4
GND
IN
V
IN
V
MON
Figure 2. RESETIN Threshold Selection
OPERATING
STATE
ENABLE
HOLD
REGULATOR
OUTPUT
COMMENT
Initial State
Low
Don’t care
Off
ENABLE is pulled to GND through an internal pulldown.
HOLD
is
floating (pulled up to OUT). Regulator output is disabled.
Turn-On State
High
Don’t care
On
ENABLE is externally driven high turning the regulator output on.
HOLD
is pulled up by OUT.
Hold
Setup State
High
Low
On
HOLD
is externally pulled low while ENABLE remains high (latches
HOLD
state).
Hold State
Low
Low
On
ENABLE is driven low (or allowed to float low by an internal pulldown).
HOLD
remains externally pulled low keeping the regulator output on.
Off-State
Low
High
(floats high)
Off
HOLD
is driven high (or allowed to float high by an internal pullup)
while ENABLE is low. Regulator output is shut off and ENABLE/
HOLD
logic returns to the initial state.
Table 3. ENABLE/
HOLD
Truth Table/State Table
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6774BTALD0+T | 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) uPower Linear Regulator RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| MAX6774BTALD1+T | 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) uPower Linear Regulator RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| MAX6774BTALD2+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX6774BTALD2+T | 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) uPower Linear Regulator RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| MAX6774BTALD3+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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